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INGERSOLL-RAND
CENTAC
CMC TECHNICAL REFERENCE MANUAL
(Part No. 22204796)
INGERSOLL-RAND
AIR COMPRESSORS
CMC TECHNICAL REFERENCE MANUAL
Copyright Notice
Copyright 1996-2003 Ingersoll-Rand Company
THIS MANUAL IS SOLD "AS IS" AND WITHOUT ANY EXPRESSED OR IMPLIED
WARRANTIES WHATSOEVER.
Printing Date: 24 March 2003
Ingersoll-Rand air compressors are not designed, intended, or approved for breathing air
applications. Ingersoll-Rand does not approve specialized equipment for breathing air
applications and assumes no responsibility or liability for compressors used for breathing air
service.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
Table of Contents
What’s New About the 3.10 Release ______________________________________1
References ___________________________________________________________2
General - CMC Panel ___________________________________________________3
Control Methodology___________________________________________________4
Performance Control _______________________________________________________ 4
PID Control _______________________________________________________________ 7
Surge Control ____________________________________________________________ 12
Prelube Pump ____________________________________________________________ 18
Oil Heater _______________________________________________________________ 18
Protection and Monitoring _____________________________________________19
Analog Functions _________________________________________________________ 19
Digital Functions _________________________________________________________ 19
Compressor Operating Methodology ____________________________________21
Stopped _________________________________________________________________ 21
Rotating_________________________________________________________________ 21
Compressor Operating States ______________________________________________ 23
OUI (Operator User Interface) _______________________________________________ 24
General Sequence of Operation _____________________________________________ 41
Indicator, Switch and Light Layout___________________________________________ 42
CMC Tuning Procedures _______________________________________________42
Setting MaxLoad__________________________________________________________ 42
Setting MinLoad __________________________________________________________ 43
Setting MinLoad Surge Index Increment ______________________________________ 44
Setting Surge Sensitivity ___________________________________________________ 44
Tuning Stability __________________________________________________________ 45
Calibrating the Control Valves ______________________________________________ 46
Autodual Control Settings __________________________________________________ 47
Setting the Start Time _____________________________________________________ 48
Setting the CT Ratio _______________________________________________________ 48
Inlet Unload Position ______________________________________________________ 48
Setting Set Point Ramp Rate ________________________________________________ 48
Alarm and Trip Settings____________________________________________________ 49
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
Troubleshooting _____________________________________________________50
Troubleshooting Example __________________________________________________ 51
Input/Output (I/O) System __________________________________________________ 52
Control Power System (CPS) _______________________________________________ 72
Controller Problems_______________________________________________________ 76
Options _____________________________________________________________78
Enclosures ______________________________________________________________ 78
Control Electrical Package _________________________________________________ 80
Stage Data Package _______________________________________________________ 80
Alarm Horn ______________________________________________________________ 80
Running Unloaded Shutdown Timer _________________________________________ 80
Water Solenoid Post Run Timer _____________________________________________ 80
Panel Mounted Wye-Delta Starter ____________________________________________ 80
N.O. Contact for Remote Indication of Common Alarm and Trip __________________ 80
Power Regulating Constant Voltage Transformer ______________________________ 80
Automatic Starting ________________________________________________________ 81
Remote 4-20 mA Pressure Setpoint __________________________________________ 82
Ambient Control plus Parallel Valve Control Logic _____________________________ 82
Mass Flow Control ________________________________________________________ 84
Steam and Gas Turbine Driven Compressors __________________________________ 85
Diesel Driven Compressors ________________________________________________ 92
Communication ______________________________________________________93
Human Machine Interface (HMI) Systems _____________________________________ 93
Direct CMC Communications with RS422/485__________________________________ 93
The CMC-MODBUS Interface________________________________________________ 94
The CMC-DF1 Interface ___________________________________________________ 115
Documentation______________________________________________________143
System Information __________________________________________________143
Status Codes ___________________________________________________________ 143
Base Control Module (BCM) _______________________________________________ 145
Operator User Interface Module (OUI) _______________________________________ 148
Universal Communication Module (UCM) Optional ____________________________ 152
Technical Specification_______________________________________________160
Glossary _____________________________________________________________1
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
Table of Figures
Figure 1: Compressed Air System ................................................................................................................ 4
Figure 2: Modulate Control .......................................................................................................................... 5
Figure 3: Autodual Control ........................................................................................................................... 5
Figure 4: Performance Control..................................................................................................................... 6
Figure 5: Prpportional Band, Pb................................................................................................................... 7
Figure 6: Proportional Plus Integral Control................................................................................................. 8
Figure 9: MinLoad and MaxLoad ............................................................................................................... 10
Figure 14: Rise to Surge ............................................................................................................................ 14
Figure 15: Changes in Discharge Pressure............................................................................................... 14
Figure 16: Surge Detection System ............................................................................................................ 16
Figure 18: Plant Air System ........................................................................................................................ 42
Figure 19: Troubleshooting Tree................................................................................................................. 50
Figure 21: Measuring Flow ......................................................................................................................... 85
Figure 22: MODBUS Messages................................................................................................................. 95
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
What’s New About the 3.10 Release
This is the initial release of the CMC Manual for version 3.10. This version was created to
support new features incorporated into the CMC Product, and provide additional
information compared with previous versions.
Specifically, new features are as follows:
1. PID Scaling, p.9
2. Valve Characterization, p.15
3. Ambient Control plus Parallel Valve Control Logic, p.82
4. Mass Flow Control, p.84
5. Support for new, high speed IR-Bus at 38.4 kbps
6. Processor upgraded from 16 MHz to 25 MHz on Base Control Module (BCM)
7. Replaceable fuse (F2) for display, p.149
8. Operator instructions on display, p.35
9. “Pop-up” window to provide useful customer information, p.28
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
1
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CMC TECHNICAL REFERENCE MANUAL
References
The following references were used in creating this document. All of this documentation is
recommended for a more detailed understanding of specific control modes and control
panel functions.
NEMA STANDARDS PUBLICATION NO. 250, Enclosures for Electrical Equipment (1000 Volts
Maximum), Revision 2, May 1988
NFPA 496 Standard for Purged and Pressurized Enclosures for Electrical Equipment, 1986
Edition
Nisenfeld, A. Eli, Centrifugal Compressors: Principles of Operation and Control, Instrument
Society of America, 1982
Moore, Ralph L., Control of Centrifugal Compressors, Instrument Society of America, 1989
Doebelin, Ernest O., Control System Principles and Design, John Wiley & Sons, 1985
Rowland, James R., Linear Control Systems Modeling, Analysis, and Design, John Wiley &
Sons, 1986
Deshpande, Pradeep B. and Ash, Raymond H., Computer Process Control With Advanced
Control Applications, 2nd Edition, Instrument Society of America, 1988
CENTAC ENERGY MASTER, Version CEM230, Ingersoll-Rand Company, March 1992
White, M.H., Surge Control for Centrifugal Compressors, Chemical Engineering, December 25,
1972
Hall, James W., THERMODYNAMICS OF COMPRESSION: A Review of Fundamentals,
Instrument Society of America, 1976
Gaston, John R., Centrifugal Compressor Operation & Control: Part II "Compressor Operation",
Instrument Society of America, 1976
Gaston, John R., Antisurge Control Schemes For Turbocompressors, Chemical Engineering,
April 1982
Warnock, J. D., Methods for Control of Centrifugal and Reciprocating Compressors, Moore
Products, 1984
Harrison, Howard L. and Bollinger, John G., Introduction to Automatic Controls, Second Edition,
Harper & Row, 1969
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
General - CMC Panel
The CMC panel is the microprocessor-based control and monitoring system for Centac.
The CMC handles compressor control and monitoring functions; as well as, control of
auxiliary equipment such as the main motor starter, oil heater, and prelube pump.
The CMC panel has a custom computer board called the Base Control Module (BCM). This
board has a microcontroller and memory chips that tell the rest of the panel what to do for
the various input pressures, temperatures and vibrations. All hardware for data analysis,
number of input and output (I/O) points and system memory are optimally selected for
accurately controlling and protecting Centac compressors.
Features of the CMC system are:
•
Ease of use ... only twelve buttons to push on the operator OUI!
•
Multiple function, 240 x 128 pixel graphic LCD to display data, operating status and
basic operator instructions.
•
Unload, Modulate and Auto-Dual operating modes.
•
Advanced surge detection and control.
•
High current limit for main drive electric motor protection.
•
First-out indication and event log to help determine the root cause of a compressor trip.
•
Pinion vibration alarm and trip for each compression stage.
•
Base Control Module CPU running at 25Mhz.
•
Base Control Module, Operator User Interface and Universal Communication Modules
capable of serial communication at 38,400 baud
•
Optional port for communicating to the Air System Controller (ASC), Air System Manager
(ASM) or other Distributed Control Systems (DCS) via MODBUS protocol.
•
Optional reduced voltage motor starter included in panel for some sizes.
NOTE
For the purpose of consistency and clarity, all of the descriptions and examples that
follow refer to "air" for the more generic "gas". Any gas compressed by a Centac
compressor would also apply.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
Control Methodology
The CMC utilizes performance and surge control methodologies to meet varying
compressed air system needs. The term "performance control" is used for grouping the
control modes that affect compressor power consumption through movement of the intake
and discharge valves.
Performance Control
The CMC has three standard performance control modes or methods of operation. These
modes are Unload, Modulate and Autodual for typical plant air compressors operating in
constant pressure applications. For the discussions that follow, Figure 1 depicts a
compressed air system and the relationship between the compressor and the plant air
system.
Atmosphere
Silencer
Inlet
Valve
Inlet
Filter
Bypass
Valve
Check
Valve
Plant Air System
Compressor
Figure 1: Compressed Air System
Unload
The compressor is unloaded, when no air is being supplied to the Plant Air System, and all
of the air produced by the compressor is being vented to the atmosphere. In this mode, the
inlet valve is slightly open to allow enough air to pass through the compressor for internal
cooling, prevention of rotor instability and surge avoidance. This air is then discharged
through the open bypass valve to the atmosphere. Typically, the compressor is set to make
a positive pressure across the first compression stage, which produces a discharge
pressure something greater than the atmospheric pressure.
The inlet valve opening required to create this positive pressure is directly related to the
horsepower consumed; therefore, careful consideration should be given to this inlet valve
position for minimizing overall power consumption.
Modulate
Constant pressure control is a frequently required performance control method for Centac
air compressors. If left uncontrolled, the compressor's discharge pressure would rise and
fall along the natural performance curve as system demand changed. Modulate control
satisfies the constant pressure requirement.
The performance map in Figure 2 shows Modulate control. Modulate maintains the system
discharge pressure at the system pressure set point as entered into the CMC by the user.
Once loaded, the compressor will operate along the constant pressure line until the user
switches to Unload or presses the stop button.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
Control is accomplished by
modulating the inlet valve within
the compressor's throttle range.
When system demand is less
than the minimum throttled
capacity, the discharge pressure
is maintained by modulating the
bypass valve and venting some
or all of the air to atmosphere.
This valve is opened just prior to
reaching the surge line.
Whenever the bypass valve is
open, the inlet valve maintains its
position at the minimum throttled
capacity setting. Modulate
provides a constant discharge
pressure with variable capacity
from design to zero.
Natural
Pressure
Curve
Constant Pressure Line
Surge Line
Design
Point
Maximum
Throttle Point
(MinLoad)
Discharge
Pressure
Unloaded
Inlet
Valve
Throttle
Range
Bypass
Valve
Throttle
Range
Natural
Power
Curve
Surge Line
Constant Power Line
Power at
Coupling
This control method is used when
stable control of the discharge
pressure is required. Modulate is
the most commonly used control
method for Centac compressors.
Unloaded
Capacity
Figure 3: Modulate Control
Energy Saving Control - Autodual
Autodual automatically loads
the machine when demand is
high and unloads the machine
when demand is low.
When the compressor is
controlling to pressure setpoint
and demand is within the inlet
valve throttle range, constant
pressure is maintained in the
same manner as Modulate.
When the machine is controlling
to the pressure setpoint and
system demand is low, the
compressor is operated in the
bypass valve throttle range.
Autodual automatically unloads
the machine when the bypass
valve is opened beyond the
Unload Point for a programmed
time period called the Unload
Delay Time. The Bypass Valve
Unload Point is selected to
correspond with the check valve
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Natural
Curve
Surge Line
Unload
Point
Design
Point
Reload Point
(Reload Percent)
Discharge
Pressure
Unloaded
Bypass
Valve
Throttle
Range
Power at
Coupling
Inlet
Valve
Throttle
Range
Unload
Point
Unloaded
Capacity
Figure 2: Autodual Control
Natural
Curve
6
CMC TECHNICAL REFERENCE MANUAL
closing since at this point the machine is not supplying the system (Figure 3). The Unload
Delay Timer should be set to prevent unloading during short excursions through the Unload
Point. The Reload Percent determines the System Pressure at which the machine will
automatically load into the system.
How does Constant Pressure Modulation Work?
The goal of constant pressure modulation is to maintain a specified discharge pressure in
the compressed air system while the capacity requirements change. Modulate control
provides constant pressure from 100 percent of the compressor's capacity to zero capacity.
Autodual control provides constant pressure from the 100 percent of the compressor's
capacity to the Unload Point.
If all plant air systems were identical in capacity usage requirements, the CMC could be
preprogrammed to respond to those changes; however, all plant air systems are not alike.
The frequency and variability of the capacity changes means that the control logic must be
flexible, so the CMC utilizes proportional, integral and derivative control algorithms to
determine the magnitude of the signal that is sent to the inlet and bypass valves. These
algorithms, or programming logic, allow the CMC control system to be "tuned" to a specific
plant air system.
Measuring the Discharge Pressure
In order to maintain constant pressure, the system discharge air pressure must be
measured. A pressure transducer is mounted in the control panel and tubed to the
compressor discharge downstream of the check valve as shown in Figure 4.
CMC
Pneumatic Tubing
PT
4-20 mA
Bypass
Valve
Base
Control
Module
4-20 mA
CT
Check
Valve
Starter
Motor
4-20 mA
PTx
Compressor
Inlet
Valve
Figure 4: Performance Control
This transducer sends a 4-20 mA signal to the CMC board. The CMC compares the
measured discharge pressure to the system pressure set point entered into the CMC by the
user through the Operator User Interface (OUI). Depending upon the difference between
these two values the CMC will send a 4-20 mA signal to "Modulate", open or close, the inlet
and/or bypass valve to maintain the specified system pressure set point.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
PID Control
Proportional Band
Proportional control varies the signal sent to the valves as a linear response to the
difference between the actual system pressure and the system pressure set point. Valve
responsiveness can be adjusted through the CMC with the proportional band, Pb, set point.
This set point is the controller gain. Gain is a scaling factor. This scaling factor, graphically
depicted in Figure 5, is the amount of change in the input variable (actual minus set point
pressures) to cause a full scale change in the output variable (valve position).
In other words, if the pressure in the air system fluctuates frequently, it would be prudent to
set Pb to a low value to keep up with those system changes. Otherwise, if the system is
very stable, a larger value can be used. Pb is directly related to valve life and indirectly
related to valve cycling; so, as Pb decreases, valve life decreases and cycling increases.
As stated earlier, the CMC uses a proportional, integral and derivative control algorithm.
The result of proportional only control is offset from the controlled variable, discharge
pressure. This means that if the set point pressure is 100, the actual pressure may only be
95. The value of this offset depends upon the
proportional band value.
What is the valve response when the difference
between actual and set point pressures is zero?
There is no response. Proportional control only
functions when a difference or error exists. Design
discharge pressure could not be attained in a
proportional only control system. Therefore, an
integral control algorithm is added to achieve the
desired discharge pressure.
Integral Time
The offset produced by the proportional control
algorithm could be eliminated by manually
readjusting the system pressure set point. Using
the example above, the set point could be reset to
105 to obtain the 100 desired. Manually resetting
the set point would be required as the system
demand fluctuated. Integral control, also known as
reset control, automatically resets the desired
system pressure set point. For the CMC, the rate
at which the controller resets the system pressure
setting is known as Integral Time, It, and is
expressed in units of repeats per second.
Output
Variable
(Valve Position)
Full Scale
Slow
Response
Pb
0
Large Change
Full Scale
Fast
Pb low
Response
Output
Variable
(Valve Position)
0
Small
Change
If precise control of the specified discharge
Input Variable
pressure is required, the It set point should be set
(Actual - Set Point Pressures)
for a fast value. It is inversely related to valve life
Figure 5: Proportional Band, Pb
and directly related to valve cycling, therefore, as
It decreases, valve life increases and cycling
decreases. For the CMC controlling Centac compressors, It values are typically less than
1.00.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
high
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CMC TECHNICAL REFERENCE MANUAL
Figure 6 shows the
relative valve response
over time for two
combinations of Pb and It.
As shown, when Pb is low
and It is fast, valve activity
is significant in both
magnitude and frequency
to obtain the desired set
point. The other scenario,
Pb is high and It is slow,
has relatively little valve
activity, and may never
reach the set point
position.
Opened
Proportional Band - Low
Integral Time - Fast
Set Point
Valve
Activity
Proportional Band - High
Integral Time - Slow
Proportional Band and
Closed
Integral Time are
Time
variables used internally
by the control system to
determine valve response
Figure 6: Proportional Plus Integral Control
and direction for a given
compressed air system. Each has an optimum value based upon the system's
characteristics. Determining these optimum values is a trial and error
exercise. These set points should be re-evaluated any time there is a major change in the
compressed air system.
Derivative action depends on the slope
of the error, unlike P and I. If the error is
constant derivative action has no effect.
The derivative term looks at the rate of
change of the input and adjusts the
output based on the rate of change.
Controller
Output
Derivative Component
Proportional Component
Error
Derivative Action
Derivative action (also called rate or preact) anticipates where the process is
heading by looking at the time rate of
change of the controlled variable (its
derivative). TD is the ‘rate time’ and this
characterizes the derivative action (with
units of seconds).
Time
Figure 7; PD Controller
Proportional-Integral-Derivative
When an error is introduced to a PID controller, the controller’s response is a combination
of the proportional, integral, and derivative actions, as shown in Figure 8.
Assume the error is due to a slowly increasing process variable. As the error increases, the
proportional action of the PID controller produces an output that is proportional to the error
signal. The reset action of the controller produces an output whose rate of change is
determined by the magnitude of the error. In this case, as the error continues to increase at
a steady rate, the reset output continues to increase its rate of change. The rate action of
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
the controller produces an output whose magnitude is determined by the rate of change.
When combined, these actions produce
an output as shown in Figure 8.
On the combined action curve, the output
is simply the sum of the individual
Proportional, Integral and Derivative
corrections.
Note: The response curves in Figure 8
are drawn assuming no corrective action
is taken by the control system.
With previous CMC versions, PID settings
could vary considerably depending upon
the variable regulated. A PID Scaling
feature has been added to the CMC. This
feature will provide for more uniform PID
settings for different process control.
Up to this point, constant pressure control
has been accomplished with an analog
input (system pressure) and two analog
outputs (inlet valve and bypass valve
position). In the following paragraphs it
will be discussed how motor current, the
other analog input, is used for constant
pressure control. Also covered in the
following paragraphs is the discussion as
to at what time the bypass valve is
modulated as opposed to inlet valve.
Error
Proportional
Only Action
Reset
Only
Action
Rate
Only
Action
Combined
Output
10%
5%
0%
20%
10%
0%
5%
0%
10%
0%
55%
40%
30%
T1
T0
1 Sec
T2
2 Sec
Figure 8: Proportional-Integral-Derivative
Motor Current, MinLoad and MaxLoad
Motor current, in units of power (normally amps), has two functions in the CMC. The first is
over current protection for the main motor, and is referred to as MaxLoad or High Load
Limit (HLL). The second function determines the point at which the bypass valve begins to
modulate for controlling pressure. This point is called MinLoad or Throttle Limit (TL). The
location of these two points is graphically depicted on the pressure and power versus
capacity curves as shown in Figure 11.
MaxLoad or High Load Limit (HLL) setpoint, in units of amps, is a parameter entered into
the CMC that prevents the main drive motor from overloading. Once this value is reached,
the CMC logic limits the inlet valve from opening any further. This action constrains the
motor by limiting the amp draw to the maximum allowable service factor amps by using the
inlet valve MaxLoad PID loop to maintain the MaxLoad current setpoint as shown in Figure
9.
When the motor is sized for cold conditions, there are circumstances when MaxLoad will
never be reached. For example, the value of MaxLoad as shown in Figure 9, cannot be
attained for the T=hot curve because it is beyond the maximum compressor capability; that
is, the inlet valve is fully open. This scenario never limits the inlet valve.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
When ambient conditions produce the
T=cold curve, the compressor will
not be able to achieve the maximum
capacity because it is beyond the
MaxLoad value. Since MaxLoad is
less than or equal to the motor
nameplate FLA times the adjusted
service factor, the maximum
compressor capacity at T=cold could
only be reached if the motor were sized
for the T=cold condition.
MinLoad Control Setpoint in units of
amps (sometimes referred to as throttle
limit TL) is the power value at which the
CMC transfers modulation control from
the inlet to the bypass valve (Figure
10). The reason for this transfer is to
prevent the compressor from entering
into a surge condition. The bypass
valve vents air to the atmosphere and
maintains the pressure setpoint by
using the bypass valve pressure PID
loop. At the same time, the inlet valve
maintains the MinLoad setpoint by
using the inlet valve MinLoad PID
loop; therefore, once the MinLoad
Figure 9: MinLoad and MaxLoad
Inlet Valve
Pressure PID
Control Zone
HLL
TL
Inlet Valve
MaxLoad PID
Control Zone
Power at
Coupling
Amps
Inlet Valve
MinLoad PID
Control Zone
MaxLoad
Capacity - Mass Flow
Bypass Valve
Pressure PID
Control Zone
Discharge
Pressure
MinLoad
Power at Coupling
Discharge Pressure
Tcold
Thot
setpoint is reached, the compressor
continues to produce a constant amount
of air. Part of this air goes to the Plant
Air System, and the remainder is blown
off. Even though the Plant Air System
receives only a portion of the air
produced, the amount of power remains
constant.
The following table presents seven
capacity requirements for a plant air
system. At each of the capacities, the
table shows the compressor output,
valve position, discharge pressure and
power. Each of these values represents
a percentage and is only an example. P2
is the specified discharge pressure and
P0 is the barometric pressure.
Capacity - Mass Flow
Figure 10: MinLoad
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
System
Required
Capacity
0
0
Compressor
Operating
State
Off
Unloaded
Compressor
Output
Capacity
0
10
Open Position
Inlet
Bypass
Valve
Valve
0
100
10
100
100
Full Load
100
100
0
P2
100
75
MinLoad
75
70
0
P2
80
50
MinLoad
75
70
25
P2
80
25
MinLoad
75
70
50
P2
80
0
MinLoad
75
70
100
P2
80
Discharge
Pressure
0
>P0
Power
0
20
From the table above, once the system required capacity moves below 75 percent, the
compressor still produces 75 percent capacity with 80 percent of the power. If the system
needs only 25 percent capacity, it will still have to pay for 80 percent of the power. This is
why it is important to open the bypass valve at the last possible moment; therefore, setting
MinLoad properly is critical for efficient energy management.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
Surge Control
As stated earlier, setting MinLoad properly is critical for efficient energy management.
Also, a well thought-out design method of transferring into and out of the MinLoad state
contributes to good Surge Control. The discussion thus far has only considered motor
current as the point at which the transition from the Loaded state to the MinLoad state
occurs. The following sections will consider methods other than motor current as to when
to transition to the MinLoad state.
‘Surge’ - Definition
Surge is the reversal of flow within one or more stages of a dynamic compressor. This
reversal takes place when the capacity being handled is reduced to a point where
insufficient pressure is being generated to maintain positive capacity. This condition can
potentially damage the compressor if it is severe and is allowed to remain in that state for a
prolonged period; therefore, control and prevention is required.
Control Methodology
Surge prevention is accomplished opening the bypass valve prior to reaching the surge
point. The point at which the bypass valve opens is MinLoad. By blowing a portion of the
air to the atmosphere, the compressed air system gets the air that it demands. The
compressor avoids surge because it is still producing the minimum air capacity.
The following methods of MinLoad control are available on the CMC.
Motor Current
Motor Current, amps
Amps vary with voltage
Natural
Surge
Points
MinLoad
Setpoint
Curve "marginally" affected by
changes in inlet temperature at a
constant inlet pressure
The most common method
determining when to transition to the
MinLoad status is by using motor
current. Motor current may be
correlated to flow through the
compressor. As flow increases
through the compressor motor
current increases as well. The most
significant factor affecting motor
current is voltage. If voltage
dropped it would cause current to
rise even though no change in flow
occurred. Therefore motor current
can vary as illustrated in Figure 11.
Capacity, scfm
Figure 11: Motor Current Method
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
Motor Power, kW
Optional Motor Power (kW)
Another method of determining when to
transition to MinLoad control on motor
driven units is by using motor power or
kilowatts (kW). This method takes into
account any changes in motor current due
to the influence of voltage. If voltage drops
and current rises, kW would remain
constant. This allows for better correlation
in flow through the compressor, therefore,
allowing for more accurate control and
potentially blowing less air to atmosphere.
Natural
Surge
Points
MinLoad
Setpoint
Curve "marginally" affected by
changes in T1 at a constant P2
This method virtually eliminated
inefficiencies due to changes in voltage.
Capacity, scfm
Figure 12: Optional Motor Power, kW
Optional Ambient Control (Polytropic Head)
Head, ft-lb/lb
Another method of determining when to transition to MinLoad control is by using Polytropic
Head calculation. For purposes of the CMC we refer to this method as Ambient Control.
Natural
Surge
Point
MinLoad
Setpoint
For a given set of
hardware (impellers
and diffusers) running
at a constant speed,
this curve is fixed
Curve unaffected by changes in
T1, P1 or P2
Capacity, icfm
Figure 13: Optional Head Control
Ambient Control calculates the work
performed by the compressor and is
expressed in foot-pounds per pound
of gas (ft-lb/lb). For a given set of
hardware, the amount of work the
compressor is capable of is fixed. If
the compressor is called upon to
exceed that amount of work, it will
surge. By knowing the amount of
work the compressor will do before
surging a more conservative
MinLoad point expressed in ft-lb/lb
may be set.
The ability to set the MinLoad point
closer to the surge line allows the
compressor to throttle more (deeper)
before blowing air to the atmosphere
and thus conserving energy.
Surge Detection
Even though the CMC controls to prevent surge, it can still occur. Insufficient rise to surge,
rapid changes in system discharge pressure, and various other reasons exist for a
compressor to surge.
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 1996-2003 Ingersoll-Rand Company
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CMC TECHNICAL REFERENCE MANUAL
Insufficient Rise To Surge
Rise to surge is the percentage of the compressor's surge pressure to discharge pressure
(see Figure 14). When an insufficient rise to surge situation exists, small fluctuations in the
air system demand and ambient temperature can cause the compressor to surge.
From Figure 14, when T=cold,
there is sufficient rise to surge. As
the ambient temperature increases
to T=hot, the amount of rise to
surge decreases because the
discharge pressure is remaining
constant and the natural curve is
changing with temperature.
T=cold
Discharge
Pressure
Rise
To
Surge
T=hot
Typically sufficient rise to surge
exists when a ten- percent rise to
surge can be achieved for the
hottest ambient that is expected
Capacity
for the site. If this design criterion
Figure 14: Rise to Surge
is followed, the control system
should be able to prevent surge for
variations in air demand and inlet temperature. The same design methodology applies for
changes in cooling water temperature for multi-stage compressors.
Changes in System Discharge Pressure
MinLoad corresponds to a specific constant discharge pressure; therefore, if the discharge
pressure changes, MinLoad must
be reset to properly control surge.
As shown in Figure 15, when the
discharge pressure is changed
from point 1 to 2, a surge can occur
at point 2 if MinLoad is not reset.
Changes in system discharge
pressure also apply, but more
subtly, when the compressor
begins to age. Dirty inlet filter
elements and fouled coolers can
change the compressor's natural
curve; so MinLoad should be
checked periodically to prevent
surge from an incorrect setting.
Rapid System Demand Changes
Discharge
Pressure
TL2
TL1
Capacity - Mass Flow
Figure 15: Changes in Discharge Pressure
When the system demand varies
rapidly over a wide range of
capacity, the controller may not react fast enough to open the bypass valve to prevent
surge. The CMC reads discharge pressure, motor amps, and approximately twenty other
pressure and temperature inputs; plus controls the inlet and bypass valve position. The
time required to do all of this approximately 100 milliseconds. When the controller is too
slow to react, it is referred to as "driving through MinLoad". The only prevention for a
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
15
CMC TECHNICAL REFERENCE MANUAL
situation like this is to set MinLoad at a more conservative value. The only negative
implication to this is reduced energy savings, because the bypass valve is opened early.
Incorrect Instrumentation Output
If the instrumentation, defined in Figure 4, is improperly calibrated or gives inaccurate
readings, the compressor could surge even though the CMC thinks it should not. Areas of
concern are insufficient power air, incorrect valve transducer calibration, and repeatability of
both inlet and bypass valves. If the valves are being sent signals for specific movements
and they do not respond by moving to the new positions, then the CMC has very little
chance of correctly controlling surge, or even the discharge pressure.
As discussed earlier, the CMC uses motor current as the standard method for determining
when to open the bypass valve. The time to begin opening the bypass valve is near
MinLoad amps. The equation,
GHP=
I× V× η
× PF× 3
motor
746
indicates that horsepower is directly related to current; it is, but it is also related to voltage.
This is not normally a concern because voltage is primarily constant. However, there are
some locations where extreme voltage variations do exist. In these circumstances, the
CMC cannot correctly determine when it reaches MinLoad and a surge can occur. For
these applications, an optional watt transducer can be used to avoid this situation.
Incorrect Valve Response
Valve Characterization is available on the CMC. Valve characterization allows a more
linear use of the valve throttling characteristics. Linear flow is a flow characteristic in which
the valve relative opening directly correlates to the percentage flow, e.g. a 50 % open valve
gives 50% of maximum flow, with a constant pressure drop across the valve. The CMC
modifies the controller output to allow a more linear response to valve throttling. This
feature requires configuration by an Ingersoll-Rand service technician.
How is Surge Detected?
Note that it has been shown that even though the CMC has surge prevention logic, a surge
can still occur. The CMC has a surge detection system comprised of a surge pressure
transducer and motor current transformer (see Figure 16). The CMC senses surge when
the rate of change in last stage discharge pressure and the rate of change in motor current
are greater than the surge sensitivity setpoint value. When this occurs, the CMC will alarm
and unload the compressor.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
Pneumatic Tubing
CMC
PT
4-20 mA
Bypass
Valve
Base
Control
Module
4-20 mA
CT
Check
Valve
Starter
Motor
4-20 mA
PTx
Compressor
Inlet
Valve
Figure 16: Surge Detection System
Surge AbsorberTM
When the controller recognizes that a surge occurred, the compressor will unload. With the
Surge AbsorberTM feature enabled, the controller will increment the bypass valve position
by a fixed percentage, send the inlet valve to the MinLoad point (if it is not already there)
and then let normal system demand reload the compressor to the operating pressure. This
process will repeat up to three times within a ten-minute period. If the compressor surges
four times in ten minutes, the compressor will remain unloaded until an operator presses
the reset button. Each detected surge drives a Surge Event to the Event Log. If the
compressor unloads due to repeated surges, a Surge Unload Alarm Event is driven to the
Event Log.
Surge Indexing
MinLoad
Surge
Index
Increment
Discharge
Pressure
MinLoad User Setpoint
MinLoad Control Setpoint
(reset returns control here)
Power at
Coupling
Amps
MinLoad Control Setpoint #3
(currently active)
MinLoad Control Setpoint #1
MinLoad Control Setpoint #1
Capacity - Mass Flow
Since the setting of MinLoad
Control Setpoint is sensitive
to many variables in a
compressed gas system,
there is potential for the
setting to require adjustment
throughout the operation of
the compressor. When
MinLoad is set incorrectly,
one of two things can
happen. When MinLoad is
set too high, the compressor
will consume excessive
power at MinLoad. When
MinLoad is set too low, the
compressor is allowed to go
past the surge line and
surge occurs.
Figure 17: Surge Indexing
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
When Surge Indexing is enabled, it corrects the situation when MinLoad is set too low by
automatically adjusting MinLoad to a higher value upon a surge. The indexed setting,
MinLoad Control Setpoint will remain in effect until MinLoad User Setpoint is Operator User
Interface, or the Reset button is held for more than five seconds. When MinLoad User
Setpoint is manually changed, the MinLoad Control Setpoint is automatically changed to
match the new setting, and when reset, the MinLoad Control Setpoint is reset to the new
MinLoad.
Entering a zero into the MinLoad Surge Index Increment variable disables surge Indexing.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
17
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CMC TECHNICAL REFERENCE MANUAL
Oil System Control
The CMC panel provides control of the prelube pump and lube oil heater in the starting
sequence, during normal operation and after compressor stops or trips.
Prelube Pump
The prelube pump is started when the panel power is on and seal air is present. The
prelube pump stops after the compressor start button is pushed and the programmable
timer “Start Time” has expired. The pump does not come on again until the Stop key is
pressed, and will remain on until the panel power is turned off or Seal Air is lost.
Oil Heater
The oil heater is thermostatically controlled. When the oil temperature is below the set point
temperature, the oil heater is energized, above the set point temperature it is de-energized.
The oil heater control does not have any interaction with the microprocessor board and is
designed to operate with the control panel de-energized as long as three-phase power is
available.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
19
Protection and Monitoring
Each CMC base module has twenty-three analog inputs, sixteen digital inputs, four analog
outputs and sixteen digital outputs for control, protection and monitoring. These input
functions provide the CMC with information about the compressor. The CMC board uses
the output functions to communicate to the user and perform actions like starting the
compressor and turning on the prelube pump. All of these inputs and outputs are required
to interface physical actions to and from the electronics.
Analog Functions
An analog function is one in which an electrical signal represents a specific pressure,
temperature, vibration and current input; or valve position output. As these inputs and
outputs fluctuate, the electrical signal to and from the microprocessor board also fluctuates
proportionally to the amount of change.
Analog Inputs
Twenty-one grounded and two floating analog inputs are used for protection, monitoring
and control. Each input used for protecting the compressor can be programmed for alarm
and trip indication. Each of these functions is pre-programmed with the function title,
engineering units, range, alarm and trip values, so no configuration is required upon receipt
by the customer.
The CMC uses pressure transmitters to measure pressure, resistance temperature
detectors (RTD) and transmitters to measure temperature, eddy current based vibration
transmitters to measure shaft vibration and a current transformer to measure the motor
current.
The CMC logic used for the protective alarm and trip functions is as follows: if the actual
value of the input is greater than or equal to the alarm or trip value, indicate the condition.
This logic is used for all inputs except, low oil pressure and low oil temperature where the
logic is reversed. To prevent nuisance alarms and trips, all standard analog inputs use an
alternate alarm and trip value during the stopped, starting, and coasting states. The
alternate setpoints cannot be edited through the Operator User Interface.
Analog Outputs
Two of the available four analog output functions are for inlet and bypass valve positioning.
These are only output functions. The standard configuration for a CMC has no input
information as to the valve location. The CMC calculates the position based upon where the
valves are supposed to be and sends those signals to the valves.
Digital Functions
A digital function is one in which the presence of an electrical signal indicates ON or YES,
and the lack of that signal represents OFF or NO. This is analogous to a light switch that
has only two states, ON or OFF. The term "discrete" is also used instead of digital in many
instances. The term that will be used throughout this documentation shall be digital.
Digital Inputs
The sixteen digital inputs provide status of field switches. Emergency Stop and Low Seal
Air Pressure trip are standard. Any of these inputs can be configured as an alarm or trip. All
inputs operate on 24 VDC power.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
Digital Outputs
The sixteen digital outputs are used by the CMC to start the prelube pump, energize the
main starter contacts, indicate that an alarm or trip condition exists, indicate that the
compressor is unloaded, activate the running unloaded shutdown timer and to sound the
horn. Outputs can operate on 120 VAC, 60 Hz, single-phase power or 24 VDC power.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
21
Compressor Operating Methodology
In the following description of compressor operation, the term “state” is used to indicate
what the compressor is doing, or mode of operation, at any given time. These operating
states exist in a hierarchy. For example, the two highest level states are “Stopped” and
“Rotating”. All other states exist at a level below these two states.
Compressor Operating States
Waiting
This state implies that the compressor is
NOT rotating. It is important to note that this
is an implication only. If the instrumentation
is not working properly or the system is setup
improperly, the compressor could be rotating.
Not Ready
Waiting
Ready
After the panel power is energized, the
controller starts the Waiting Timer and does
not allow further User operation until after the
timer expires. This timer is set at the factory
for two minutes (120 seconds) and is not
adjustable. This period allows the
compressor prelube pump to circulate oil
throughout the casing and prevents
restarting while the compressor is coasting
down after an electrical interruption.
Motor Driven Packages
+
Compressor
+
+
Stopped
Stopped
Rotating
Starting
Unloaded
A-D Unloaded
Surge Unload
Loading
MinLoad
Loaded
Full Load
Not Ready
When in this state, the compressor is “Not
Ready To Start”. This state is entered when
Unloading
the Waiting Timer has expired and any time
Coasting
that a compressor trip has been identified. A
very common and quite often overlooked
reason for the compressor being “Not Ready” is when the Emergency Stop push button has
been engaged. This state can exist indefinitely.
MaxLoad
Ready
Similar to the previous state, this state could be redefined as “Ready to Start”. This state is
entered when all compressor permissive functions have been satisfied. This state can exist
indefinitely.
Rotating
This mode does not necessarily mean that the compressor is actually rotating. It means that
it is possibly rotating or rotation is pending and expected.
Starting
Any time after the compressor is ready and a start command is given, this state is entered.
The goal for this period is to get the compressor to rated speed and running unloaded.
“Starting” is allowed for only the Start Timer period and is adjustable. This time period is
limited to a maximum of one minute, or 60 seconds. The reason for the limit is to prevent
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
the compressor from operating in the critical speed for an extended period. Stage vibration
alarm and trip setpoints are increased during this period to get the compressor through the
critical speed region. After the compressor has “Started”, the alarm and trip setpoints are
adjusted back to their original values. The same procedure occurs for stage air temperature
also.
This state exits only after the Starting Timer has expired. THE COMPRESSOR IS ALWAYS
STARTED UNLOADED. On exit of “Starting”, the compressor will return to the mode that it
was in the last time it ran. For example, typical operation implies that prior to stopping the
compressor, the Unload key is pressed. If this occurred, then the compressor will remain in
“Unload” after starting. If the compressor was running and tripped, the compressor will
automatically return to the “Loaded” mode on exit of the Starting state. The User may also
press the Load or Unload key prior to pressing the Start key to force the compressor to into
either post-Starting state.
Unloaded
The compressor is in this state after a start (and Load Selected is not in effect) or when the
User issues an unload command. A-D Unloaded and Surge Unload are also considered
states. However, these two states are really just reasons for being in the Unloaded state. AD Unloaded means “AutoDual Unloaded” which occurs when AutoDual is enabled and the
system pressure has been high enough for a long enough time to drive an unload
command. “Surge Unload” is similar in that a surge event drives the unload command
instead of AutoDual. These states can exist indefinitely.
Loading
When a valid load command is issued, the compressor will enter this state. This state exists
until the MinLoad state is satisfied. The duration of this state depends upon PID settings for
the inlet valve at the MinLoad state and the demand for air.
MinLoad, Loaded, Full Load and MaxLoad
These states transition among themselves as demand for air changes. “MinLoad” means
that the bypass valve is controlling pressure and the inlet valve is maintaining the MinLoad
Control Setpoint. “Loaded” means that the inlet valve is controlling pressure and the bypass
valve is closed. “Full Load” occurs when the inlet valve has reached the full open or 100%
position. “MaxLoad” means that the inlet valve is maintaining the MaxLoad Setpoint to
prevent motor damage. In both the “Full Load” and “MaxLoad” states, system pressure may
be lower than setpoint pressure.
Unloading
This state occurs when a valid Unload command is issued and will persist until the
compressor reaches the Unloaded state.
Coasting
When a trip or any stop command is issued and the compressor is running, the motor will
be de-energized and the compressor will begin to coast to a Stopped state. This state will
remain as long as the adjustable Coast Timer is in effect. At the end of the timer, the
compressor will enter either the Ready or Not Ready state.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
WARNING
Failure to set the Coast Timer for a period greater than or equal to the actual
coasting time can result in compressor damage.
Compressor Operating States
The following diagrams graphically depict the states relative to valve position. This diagram
is provided to assist in the understanding of overall compressor operation.
Compressor Operating States
Coasting
Unloaded
Unloading
MaxLoad
Loaded
Full Load
Loaded
MinLoad
Loading
Starting
Unloaded
Ready
Not Ready
Waiting
with Valve Position
System Pressure Setpoint
Inlet
Valve
Bypass
Valve
System Pressure
milli
amps
%
100 20
4
100
75 16
8
75
12
50
16
25
20
0
%
milli
amps
Unload
50 12
Stop
or Trip
Tight Closure
25
8
0
4
Load
Start
Inlet Valve Unload Position
Power
On
Stopped
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Rotating
24
CMC TECHNICAL REFERENCE MANUAL
User Interface
OUI (Operator User Interface)
User interface is defined as the means by which people interact with the compressor
control system. The standard configuration of the CMC has two components of the user
interface. They are the OUI and the device plate. The key component of "easy to use" is
that there are only twelve buttons to press on the OUI and four buttons, lights, and switches
on the device plate.
The CMC OUI consists of six command buttons (Start, Stop, Load, Unload, Acknowledge
and Reset), four navigation keys (Up, Right, Left and Down), an Edit mode selection key
(Enter) and a Contrast key. These keys in conjunction with the 240x128-pixel graphics
display make up the user interface to the compressor. The bezel that surrounds the OUI
ensures that the NEMA 4 rating is maintained for the OUI.
CENTAC Microcontroller
SYSTEM
System
Pressure
Pressure
Setpoint
INFO
SETTINGS
105.3
105.0
173.4
Motor
Current
Running Hours 11445
Loaded
Inlet
Valve
Bypass
Valve
22JUL96
95
0
12:00:00
Load Selected
Remote
1/2
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
25
Command Keys
These keys “command” the compressor to perform actions as specified in the following
table. When any of these keys are pressed the action will be logged in the event log.
Key
Name
Acknowledge
Reset
Function
Silences the optional horn or
acknowledges an alarm.
Clears all trip latches. Required to be
pressed after a trip condition to restart
the compressor.
Starts the compressor.
Start
Stop
Load
Stops the compressor. This button
should be pressed instead of the E-Stop
for normal operation.
Engages Modulate or Autodual control
mode.
Unloads the compressor.
Unload
Enter Key - Display Operating Mode
The Enter key toggles the display between the NAVIGATION mode and the EDIT mode.
Navigation Keys
The arrow keys for Up, Right, Left and Down perform differently depending upon the current
display-operating mode.
FOLDER NAVIGATION
To move among the tabbed folders, press the RIGHT or LEFT key. The folder list is
circular; that is, when the SYSTEM folder is displayed and the LEFT key is pressed, the
SETTINGS folder becomes active. The same is true when the SETTINGS folder is
displayed and the RIGHT key is pressed, the SYSTEM folder becomes active.
PAGE NAVIGATION
To move among each folder’s pages, press the UP and DOWN keys. The page list is also
circular. So, when page 1/4 (pronounced page 1 of 4) is active and the UP key is pressed,
page 4/4 becomes active. Also, when page 4/4 is active and the DOWN key is pressed,
page 1/4 becomes active. The current page for a folder is persistent. For example, if you
begin on the SYSTEM folder page 2, change to the INFO folder and return to the SYSTEM
folder, page 2 will be the page displayed.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
Contrast Key
This key changes the contrast of the backlight for the graphic LCD display. Pressing this
key steps among each of the thirty two contrast levels. When stepped to the thirty second
level, pressing the key again returns to the first contrast level.
Graphic Display
The 240x128-pixel graphic display allows us to provide a flexible interface between the user
and the compressor. The display has three distinct regions as shown in the diagram below.
Folders
SYSTEM
Page
System
Pressure
Pressure
Setpoint
Motor
Current
Status Bar
INFO
SETTINGS
105.3
105.0
173.4
Loaded
Compressor
Operating
State
Inlet
Valve
Bypass
Valve
22JUL96
95
0
12:00:00
Load Selected
Remote
1/2
Compressor
Control
Location
Page Number
Compressor
Status
Graphics Display Area Definitions
Folder and Page
In the design of this system, it is important to provide much of the information required for
operating and troubleshooting the compressor. The tabbed folder with multiple pages
metaphor has been used to reduce the complexity of a traversing at least sixteen pages of
information. For the standard design, the maximum number of keys required to get to any of
the sixteen pages is six. The SYSTEM folder provides information about the compressor
system, the INFO folder gives various types of information about the unit and the
SETTINGS folder is used to perform compressor setup.
Status Bar
The Status Bar provides four distinct types of information (Compressor Operating State,
Compressor Status, Compressor Control Location and Page Number). This region is
always visible from any folder and page combination.
This Field is displayed in large text so that the operator can determine the compressor’s
current operating state at a glance. See Section titled “Compressor Operating Methodology”
for a list of the messages provided.
The Compressor Status Field messages are Trip, E-Stop (emergency stop button
pressed), RMT-Stop (a remote stop has been pressed), Start Disabled (an optional
permissive start condition has not been satisfied), Alarm, Unload Selected (the
compressor will stay in “Unload” after “Starting” has been completed), and Load Selected
(the compressor will go to “Minload” after “Starting” has been completed).
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
The Compressor Control Location Field messages are Local, Remote (remote hardwired
commands i.e. start, stop, load, unload etc.), Network (MODBUS, DF1 or ASC
communication with a UCM) and Remote/Net (both Remote and Network). This indication
is provided to indicate to the operator that a remote location is in control of the compressor
and the compressor may start, stop, load, unload, etc. without the local operator initiating
any commands.
These three fields combine to provide the operator with the necessary information to create
a cursory determination of the status of the compressor. When a more thorough
determination is required, the operator can get additional detail by looking through the other
pages in the system.
The Page Number indicates the current page for the current folder with the number of
pages in the folder. The number of pages is given so that the user always knows where he
is in the system.
Navigation Mode
Navigation mode is active when a folder name (SYSTEM, INFO or SETTINGS) is
highlighted.
Edit (Setpoint Changes) Mode
Edit mode is activated by pressing the ENTER key. In Edit mode one can change
Setpoints for a page. Once in this mode, the highlight will move from around the folder
name to the item to be changed. Use the Right and Left arrow keys to move among the
changeable items and the Up and Down arrow keys to change the value of the item. When
changes are complete, press the Enter key again to return to Navigation mode.
Scroll Mode
Scroll mode is activated by pressing the ENTER key when a folder name INFO is
highlighted and the Event Log or the Routine Start / Stop page is visible. The Scroll mode
is used to page through the event log. To move among the pages, press the UP or DOWN
keys. To deactivate the Scroll mode, press the Enter key.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
27
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CMC TECHNICAL REFERENCE MANUAL
Pop-up Message
In the event of an Alarm or Trip, a pop-up message will appear providing the customer with
the phone number of the local Ingersoll-Rand representative. If the event is a Trip, the
event log on the SYSTEM folder will be displayed with the pop-up message centered over
the displayed page. The message may be removed by pressing the ENTER key. The
following are examples of the pop-up message in the event of an Alarm or Trip.
Alarm Example
SYSTEM
INFO
SETTINGS
105.1
100
Pressure
0
Setpoint 105.0
Motor
323.4
Current
Press ENTER key to continue
System
Pressure
Inlet
For Parts orValve
Service
Please Call:Bypass
Valve
39 02 950 56499
Running Hrs: 11445
Loaded
31-AUG-1999 12:00:00
Load Selected
Remote
1/4
Trip Example
SYSTEM
1
2
3
4
5
6
7
INFO
SETTINGS
Event Name
Time
Date
Low Oil Pressure
09:18:44 0720
For PartsTrip
or Service
Low Oil Pressure
Alarm
09:18:43 0720
Please Call:
Reset key pressed
09:18:34 0720
39 02 950Trip
56499 09:08:43 0720
Low Oil Pressure
Low Oil Pressure Alarm
08:58:23 0720
LoadPress
key pressed
08:24:01 0720
ENTER key to continue
Start key pressed
08:23:12 0720
Not Ready
Trip
Remote
2/3
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
SYSTEM Folder
SYSTEM
System
Pressure
Pressure
Setpoint
Motor
Current
INFO
105.1
105.0
323.4
Inlet
Valve
Bypass
Valve
Temperature
95.8
93.5
115.3
80.1
Load Selected
Remote
2/4
Loaded
INFO
RESET
SETTINGS
Digital Inputs
Starter Feedback
E-Stop Pressed
Low Seal Air
INFO
SETTINGS
Digital Outputs
Prelube Pump Running
CR1
Remote Trouble
SYSTEM
CONTRAST
UP
RIGHT
DOWN
1
2
3
4
5
6
7
INFO
SETTINGS
Event Name
Low Oil Pressure Trip
Low Oil Pressure Alarm
Reset key pressed
Low Oil Pressure Trip
Low Oil Pressure Alarm
Load key pressed
Start key pressed
Not Ready
SYSTEM
INFO
SYSTEM
Date
0720
0720
0720
0720
0720
0720
0720
Trip
Remote
2/6
Load Selected
Remote
3/6
SETTINGS
39 02 950 56499
Loaded
Load Selected
Remote
4/4
SYSTEM
Navigation and
Enter Keys
Load Selected
Remote
4/6
Ready
R E P
Part No.
12345678
12345678
12345678
12345678
12345678
12345678
INFO
Load Selected
Remote
5/6
Ready
SYSTEM
INFO
SETTINGS
Ready
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Load Selected
Remote
6/6
100.0
100.0
1.0
9.0
Load Selected
Remote
2/6
INFO
SETTINGS
PB
Inlet Valve
Pressure
MinLoad (TL)
MaxLoad (HLL)
Bypass Valve
Pressure
10.00
25.00
99.99
10.00
INFO
IT
rep/sec
D
sec
0.50
0.50
0.50
0.00
0.00
0.00
0.50
0.00
Load Selected
Remote
3/6
Loaded
SETTINGS
Control Mode
Manual
Modulate
Autodual
Reload Pressure, % of Setpoint
Unload Point, BV % Open
Unload Delay Time, seconds
INFO
SETTINGS
Starting Timer, seconds
Coasting Timer, seconds
CT Ratio
Inlet Unload Position, %
Setpoint Ramp Rate, pressure/scan
SETTINGS
Stage 1 Temperature
Stage 1 Vibration
Stage 2 Temperature
Stage 2 Vibration
Oil Pressure
High Oil Temperature
Low Oil Temperature
Loaded
20
240
60
15
5.0
Load Selected
Remote
5/6
Loaded
INFO
98
1
1
Load Selected
Remote
4/6
Loaded
SYSTEM
R O U T I N E
S T A R T / S T O P
Prior to starting, the operator should
become familiar with the operation of
the main driver. Refer to the driver
manufacturer's instructions in the
Operation Manual. The operator should
also be familiar with all the accessory
and optional equipment contained on the
400.0
Loaded
SYSTEM
SETTINGS
L A C E M E N T
P A R T S
Description
Inlet Filter Element Primary
Inlet Filter Element Secondary
Oil Filter
Demister Element
Lubricant, 55 gallon drum
Lubricant, 5 gallon drum
SETTINGS
Surge Absorber Enabled
Surge Sensitivity
SYSTEM
For parts or service contact your
local Ingersoll-Rand representative
at the following number:
INFO
MaxLoad (HLL)
MinLoad
User Setpoint (TL)
Control Setpoint
Surge Index Increment
SYSTEM
12338
11445
11223
35
2.51
INFO
*
1999/08/31
12:30:00
Load Selected
1/6
Remote
Loaded
SYSTEM
Time
09:18:44
09:18:43
09:18:34
09:08:43
08:58:23
08:24:01
08:23:12
SETTINGS
Loaded
SETTINGS
Date, yyyy/mm/dd
Time, hh:mm:ss
Load Selected
Remote
1/6
Loaded
INFO
Password
* * *
Setpoint Changes Enabled
Language and Units
English
degF mils amps psi
English
degC mils amps kg/cm2
ENTER
STOP
BCM Ver:
SYSTEM
UNLOAD
Power On Hours
Running Hours
Loaded Hours
Number of Starts
Load Selected
Remote
3/4
Loaded
LOAD
SETTINGS Folder
SETTINGS
LEFT
SYSTEM
Vibration
0.25
0.22
INFO
HORN SILENCE
START
SETTINGS
Pressure
Stage 1
30.1
Stage 2 106.6
Oil
18.8
Water
SYSTEM
100
0
31-AUG-1999 12:00:00
Load Selected
Remote
1/4
Loaded
INFO
SYSTEM
SETTINGS
Running Hrs: 11445
SYSTEM
INFO Folder
Alarm
Trip
120
125
0.80
1.00
120
125
0.75
0.95
18
16
120
125
100
95
Load Selected
Remote
6/6
30
CMC TECHNICAL REFERENCE MANUAL
SYSTEM Folder
The SYSTEM folder provides information about the compressor system. The number of
pages in this folder is at least four; but could be more for two stage machines with special
analog options purchased, or for
compressors with three stages or
SYSTEM
INFO
SETTINGS
more.
System
Pressure
105.1
105.0
323.4
Inlet
Valve
100
0
This page shows the main
compressor operating parameters,
running hours, date and time. The
Motor
System Pressure and Pressure
Current
Setpoint are in units as defined by
31-AUG-1999 12:00:00
Running Hours: 11445
the Settings page, Motor Current is
Load Selected
in Amps and valve positions are in
Remote
1/4
percent open. Pressure Setpoint is
always editable while the Inlet and
System Folder – Page 1: System Pressure
Bypass Valve positions are edit
enabled when in the Manual mode
only. These are the only editable settings in any folder other than the Settings Folder.
Pressure
Setpoint
Bypass
Valve
Loaded
Info Folder Page 1 Edit Parameters Table
Variable
Pressure Setpoint
Minimum
Value
Maximum
Value
Step
Size
0.0
999.9
0.1
Units
pressure
Inlet Valve Position (manual mode only)
percent
0
100
1
Bypass Valve Position (manual mode only)
percent
0
100
1
The Analog Input page provides the
actual value for each stage pressure,
temperature and vibration, oil pressure
and temperature. If additional analog
inputs have been purchased or more
stages exist as standard, it is likely that an
additional page or pages will be added.
The units are as defined by the Settings
page. There are no editable setpoints on
this page.
The Digital Input page shows the current
state of the digital (discrete) inputs for the
system. The number of inputs will vary
depending upon the number of optional
inputs purchased. A check in the box to
the left of the text indicates a TRUE
condition, whereas, no check indicates a
FALSE condition. For example, a check
mark in the “E-Stop Pressed” boxed
means that the Emergency Stop push
button has been pressed. It is possible to
have multiple Digital Input pages.
SYSTEM
INFO
Press
30.1
106.6
20.3
Stage 1
Stage 2
Oil
Loaded
SYSTEM
SETTINGS
INFO
Temp
95.8
93.5
105.5
Vib
0.25
0.22
Load Selected
Remote
2/4
SETTINGS
Digital Inputs
Starter Feedback
E-Stop Pressed
Low Seal Air
Loaded
Load Selected
Remote
3/4
System Folder - Pages 2,3: Analog/Digital Inputs
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
31
CMC TECHNICAL REFERENCE MANUAL
SYSTEM
INFO
SETTINGS
Digital Outputs
Prelube Pump Running
CR1
Remote Trouble
Loaded
Load Selected
Remote
4/4
System Folder - Page 4: Digital Outputs
The Digital Output page is similar
to the Digital Input page except
that it shows the current state of
the digital (discrete) outputs for the
system. The number of outputs will
vary depending upon the number
of optional items purchased. A
check in the box to the left of the
text indicates a TRUE condition,
whereas, no check indicates a
FALSE condition. It is possible to
have multiple Digital Output pages.
The SYSTEM folder’s four pages
give the current operating status for the compressor. The User is always within two
keystrokes of all operating parameters.
INFO Folder
The INFO folder contains the OUI key map, the compressor event log, the hour meters, the
phone number to call for parts or service, a list of part numbers for consumable parts and
routine start/stop and
maintenance instructions. There
INFO
SETTINGS
SYSTEM
are no editable setpoints in this
Event Name
Time
Date
folder. The OUI key map will be
1 Low Oil Pressure Trip
09:18:44 0720
the default page on power up.
2 Low Oil Pressure Alarm
09:18:43 0720
The keys are labeled in English
3 Reset key pressed
09:18:34 0720
4
Low
Oil
Pressure
Trip
09:08:43 0720
and the local language,
5 Low Oil Pressure Alarm
08:58:23 0720
depending upon the current
6 Load key pressed
08:24:01 0720
language selected.
7 Start key pressed
08:23:12 0720
Trip
The Event Log details the last
Remote
2/6
two-hundred twenty four (224)
“events” that have occurred.
Each “event” has a date and time
Info Folder - Page 2: Scrollable Event Log
stamp. This log will list all Alarms
and Trips and provides first-out indication. Any time an Alarm or Trip is indicated on the
Status Bar, the detail for that fault is included here.
Not Ready
The event labeled as “1” is the newest event and “7” is the oldest event. For events that
have identical Time and Date values, the order is still correct (newest to oldest, top to
bottom). Once the list is full, each new event knocks off the last event.
Pressing the Enter key to initiate Scroll Mode allows access to events 17 through 224.
Scroll Mode is indicated by the reverse video of the event numbers. Each Down Arrow
press displays the next seven events. An Up Arrow press will display the previous seven
events. Any time a Trip occurs, the system will send the display to the first seven events.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
32
CMC TECHNICAL REFERENCE MANUAL
Possible Events List
Event Name
Description
* * End of List * *
Displayed for the event name whenever the event list is not full.
A/I Alarm
The actual value for Analog Input “AI” is greater than the Alarm value.
A/I Trip
The actual value for Analog Input “AI” is greater than the Trip value.
Acknowledge (Location)
An Acknowledge command has been issued from Location.
Auto Dual Mode Enabled
The Auto Dual Mode has been enabled
Auto Start
An automatic start occurred (typically from Auto Hot or Cold Start).
Auto Stop
An automatic stop occurred (typically from Running Unloaded Shutdown Timer).
BCM 2 Failure Alarm
Communications have been lost to Base Control Module #2.
BCM 3 Failure Alarm
Communications have been lost to Base Control Module #3.
Compressor Started
The compressor has started.
DI Alarm
The Discrete Input “DI” is in an alarm condition.
Discrete Surge
A discrete surge switch has detected a surge.
DI Trip
The Discrete Input “DI” is in a trip condition.
Driver Trip
Drive controller feedback was not received after a start command was issued
Edit-x AI Alarm SP
The Analog Input “AI” Alarm setpoint value has been edited from location x.
Edit-x AI Trip SP
The Analog Input “AI” Trip setpoint value has been edited from location x.
Edit-x A/D Reload Pct
The AutoDual Reload Percent value has been edited from location x.
Edit-x A/D Unload Dly
The value has been edited from location x.
Edit-x A/D Unload Pt
The AutoDual Unload Point value has been edited from location x.
Edit-x AHS Pressure
The Auto Hot Start Pressure value has been edited from location x.
Edit-x Auto Stop Time
The Auto Stop Timer value has been edited from location x.
Edit-x BV Position
The Bypass Valve Position value has been edited while in Manual from location x.
Edit-x BV-PID D
The Bypass Valve Pressure PID Derivative value has been edited from location x.
Edit-x BV-PID It
The Bypass Valve Pressure PID Integral Time value has been edited from location x.
Edit-x BV-PID Pb
The Bypass Valve Pressure PID Proportional Band value has been edited from location x.
Edit-x Coasting Timer
The Coasting Timer value has been edited from location x.
Edit-x CT Ratio
The CT Ratio value has been edited from location x.
Edit-x Day
The Day value for the Date field has been edited from location x.
Edit-x IV Position
The Inlet Valve Position value when in Manual has been edited from location x.
Edit-x IV Unload Pos
The Inlet Valve Unload Position value has been edited from location x.
Edit-x IV-PID D
The Inlet Valve Pressure PID Derivative value has been edited from location x.
Edit-x IV-PID It
The Inlet Valve Pressure PID Integral Time value has been edited from location x.
Edit-x IV-PID Pb
The Inlet Valve Pressure PID Proportional Band value has been edited from location x.
Edit-x MaxLoad SP
The MaxLoad Setpoint value has been edited from location x.
Edit-x MaxLoad-PID D
The Inlet Valve MaxLoad PID Derivative value has been edited from location x.
Edit-x MaxLoad-PID It
The Inlet Valve MaxLoad PID Integral Time value has been edited from location x.
Edit-x MaxLoad-PID Pb
The Inlet Valve MaxLoad PID Proportional Band value has been edited from location x.
Edit-x MinLoad Index
The MinLoad Surge Index Increment value has been edited from location x.
Edit-x MinLoad SP
The MinLoad Setpoint value has been edited from location x.
Edit-x MinLoad-PID D
The Bypass Valve Pressure PID Derivative value has been edited from location x.
Edit-x MinLoad-PID It
The Bypass Valve Pressure PID Integral Time value has been edited from location x.
Edit-x MinLoad-PID Pb
The Bypass Valve Pressure PID Proportional Band value has been edited from location x.
Edit-x Month
The Month value for the Date field has been edited from location x.
Edit-x PSP Ramp Rate
The Pressure Setpoint Ramp Rate value has been edited from location x.
Edit-x Process SP
The Process Set Point value has been edited from location x.
Edit-x Sensitivity
The Surge Sensitivity value has been edited from location x.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
Edit-x Starting Timer
The Starting Timer value has been edited from location x.
Edit-x Sys Press SP
The System Pressure Setpoint value has been edited from location x.
Edit-x Time
The Time value has been edited from location x.
Edit-x Waiting Timer
The Wait Timer has be edited from location x.
Edit-x Year
The Year value for the Date field has been edited from location x.
E-Stop pressed
Emergency Stop push button has been pressed.
Fail to Roll
Did not achieve minimum slow roll speed in allotted time
Illegal Rotation
Unexpected rotation from driver
Load (Location)
A Load command has been issued from network communications.
Loss of Motor Current
Motor current feedback was lost while running.
MinLoad Clamped
The MinLoad Control or User Setpoint value has been limited to the MaxLoad Setpoint value.
MinLoad Incremented
The MinLoad Control Setpoint value has been incremented as a result of surge.
MinLoad Reset
The MinLoad Control Setpoint value has been reset to the MinLoad User Setpoint value.
Modulate Mode Enabled
The Modulate Mode has been enabled.
Power Down
The Base Control Module (BCM) was de-energized.
Power Up
The Base Control Module (BCM) was energized.
Reset (Location)
A Reset command has been issued from Location.
Start (Location)
A Start command has been issued from Location.
Starter Failure
Starter feedback was not received after a Start command was issued.
Starter Fault-Closed
Motor stopped but feedback present for 2 seconds
Starting Fail
Driver feedback was not received after a Start command was issued.
Stop (Location)
A Stop command has been issued from Location.
Surge
The controller has detected a Surge.
Surge Unload Alarm
The alarm condition when the compressor has unloaded as a result of multiple surges.
TTV Switch Fault
Trip Limit Switch Stuck
Unload (Location)
An Unload command has been issued from Location.
NOTE 1: “Location” is replaced by “Comm” for communications network, “Local” for local compressor display and “Remote” for
hardwired remote communications.
NOTE 2: “x” is replaced by “C” for edits from a communication network and “L” for edits from the local display.
NOTE 3: All Analog Inputs that have alarm and trip sepoints get edit local, edit communications, alarm and trip event
messages.
NOTE 4: All Discrete Inputs for Alarm or Trip get alarm and trip event messages.
This next page of the INFO Folder shows the hour meters and number of starts. Power On
Hours is the time that the panel
INFO
SETTINGS
power has been on. The Running
SYSTEM
Hours are the amount of time that
Power On Hours
12338
the compressor has been
Running Hours
11445
Loaded Hours
11223
operating between all start and
Number of Starts
35
stop sequence. The Loaded
Hours is the amount of time that
the compressor has been running
BCM Ver: 3.00
and not running unloaded. It can
also be defined as the number of
Load Selected
Remote
3/6
hours that the inlet valve is not in
the Inlet Unload Position. The
Info Folder – Page 3: Hour Meters and Version
Number of (Compressor) Starts is
self-explanatory.
Loaded
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
33
34
CMC TECHNICAL REFERENCE MANUAL
NOTE
Most electric motors are only rated for two cold starts or one hot start per hour. It is
the operator’s responsibility not to exceed the electric motor’s limitation. The control
system allows the compressor to be started when the compressor is ready, not the
motor.
The last item on this page is the Base Control Module Version number. This will be used by
field personnel for quick reference to determine if newer software is available.
This page of the INFO folder
shows the phone number to call for
parts or service. This is the
number of the local Ingersoll-Rand
representative. The number can be
changed only by use of Service
Tool.
INFO
SYSTEM
SETTINGS
For parts or service contact your
local Ingersoll-Rand representative
at the following number:
39 02 950 56499
Trip
Remote
Ready
4/6
Info Folder – Page 4: Phone Number
This page provides a list of
consumable parts found on the
compressor package. These parts
may also be located in the
compressor bill of materials. In the
event of a discrepancy, the
compressor’s bill of materials always
takes precedence over this page. In
the event that the part numbers are
not available, such as retrofitting the
CMC on a competitive machine, this
screen may not be visible.
INFO
SYSTEM
R E P
Part No.
12345678
12345678
12345678
12345678
12345678
12345678
SETTINGS
L A C E M E N T
P A R T S
Description
Inlet Filter Element Primary
Inlet Filter Element Secondary
Oil Filter
Demister Element
Lubricant, 55 gallon drum
Lubricant, 5 gallons
Ready
Trip
Remote
5/6
Info Folder – Page 5: Replacement Parts
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
35
CMC TECHNICAL REFERENCE MANUAL
Basic operator instructions are provided on the Routine Start/Stop and Maintenance pages.
Pressing the Enter key to initiate Scroll Mode allows access to the entire instructions.
Scroll Mode is indicated by the reverse
video of a slide bar. Each Down Arrow
INFO
SETTINGS
SYSTEM
press displays the next eight lines of
R O U T I N E
S T A R T / S T O P
instructions. An Up Arrow press will
Prior to starting, the operator should
display the previous eight lines of
become familiar with the operation of
the main driver. Refer to the driver
instructions. The slide bar on the page
manufacturer's instructions in the
indicates current location within the text.
Operation Manual. The operator should
If a Trip occurs while on this page, the
also be familiar with all the accessory
system will send the display to the event
and optional equipment contained on the
log page.
Trip
Ready
Remote
6/6
Info Folder – Page 6: Operator Instructions
SETTINGS Folder
The SETTINGS folder is used for compressor setup. In this folder, the User will enter
performance and control operating parameters, analog health monitoring settings for Alarm
and Trip conditions, control mode selection, setpoint changes, password, and user interface
language. This folder is the primary location for editing setpoints.
The Password is used for determining
whether Setpoint Changes can be
made. The Password takes four
numbers. If the Password is entered
properly, Changes will be enabled (a
check will be in the box); otherwise,
they are disabled. This enabling and
disabling applies to all changeable
setpoints except, Pressure Setpoint,
Throttle Limit, language selection and
the Password, these items are always
modifiable.
SYSTEM
INFO
SETTINGS
Password
* * *
Setpoint Changes Enabled
Language and Units
English
degF mils amps psi
English
degC mils amps kg/cm2
Date, yyyy/mm/dd
Time, hh:mm:ss
Loaded
*
1999/08/31
12:30:00
Load Selected
Remote
1/6
Settings Folder - Page 1: Password, Language,
Each control system is shipped with
Time and Date
two languages and units of measure
combinations. The first set is for the English language, pressures in units of PSIG,
temperatures in units of degrees F and vibrations in units of mils. The other set will be
localized for the customer. The default alternate language is English with Metric units.
Language support will be provided for those listed in the Technical Specification located at
the end of the manual. Others will be available as required and translations can be
obtained. This system has the ability for any language because of the graphics display.
Asian character support will require additional screens because these characters require
four times the number of pixels. There are no limitations on the units of measure. Each
analog input has its own scaling factor and offset.
The Date is set with three separate values (1) Year, including century (2) Month and (3)
Day. The Time is also set with three values (1) Hour, (2) Minutes and (3) Seconds.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
36
CMC TECHNICAL REFERENCE MANUAL
Settings Folder Page 1 Edit Parameters Table
Variable
Units
Minimum
Value
Maximum
Value
Step
Size
1
Password Digit
dimensionless
0
9
Date (Year)
years
1990
2089
1
Date (Month)
months
1
12
1
Date (Day)
days
1
31
1
Time (Hour)
hours
0
23
1
Time (Minute)
minutes
0
59
1
Time (Second)
seconds
0
59
1
The Anti-surge Settings and Driver Over-Load Protection Page has all of the settings for
controlling and detecting surge conditions and protecting the main driver from over load
conditions.
The MaxLoad (HLL) setpoint
prevents the compressor driver
SYSTEM
INFO
from overloading. MinLoad User
MaxLoad (HLL), amps
400.0
Setpoint (TL) is the value used to
MinLoad
determine what the initial (before
User Setpoint (TL), amps
100.0
Control Setpoint, amps
100.0
indexing) motor current value will
Surge Index Increment, amps
1.0
be when constant pressure control
operation switches from the inlet
Surge Absorber Enabled
valve to the bypass valve.
Surge Sensitivity
9.0
MinLoad Control Setpoint is the
Load Selected
Remote
2/6
actual value used to determine
when the bypass valve begins
Settings Folder - Page 2: Anti-Surge and Driver
constant pressure control in lieu of
Over-Load Protection
the inlet valve. This value equals
the MinLoad User Setpoint plus the
number of surges times the index increment value. MinLoad Surge Index Increment is the
value that the Control Setpoint is indexed after a surge has been detected. If the value for
Surge Index Increment is equal to zero, Surge Indexing is disabled.
SETTINGS
Loaded
To reset the MinLoad Control Setpoint to the MinLoad User Setpoint, hold the reset key for
at least five seconds. The indication that it has been reset will be in the event log. The
event message “MinLoad Reset” will be displayed. Another indication is when the MinLoad
User Setpoint value equals the MinLoad Control Setpoint value.
The Surge Absorber Enabled checkbox allows the user to turn off or on the Surge Absorber
feature. When disabled, the compressor will Unload on any surge condition.
The Surge Sensitivity setting has a range from zero (0.0) to ten point nine (10.9) where one
is not sensitive (a “soft” surge condition could exist without being identified) and ten is very
sensitive (a “soft” surge condition would be identified). We ship the machine with a default
value of nine (9). This setting will pick up most surge conditions.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
37
CMC TECHNICAL REFERENCE MANUAL
Settings Folder Page 2 Edit Parameters Table
Variable
Units
Minimum
Value
Maximum
Value
Step
Size
MaxLoad (HLL)
amps
0.0
9999.9
0.1
MinLoad User Setpoint (TL)
amps
0.0
100.0
0.1
MinLoad Surge Index Increment
amps
0.0
9999.9
0.1
Surge Sensitivity
dimensionless
0.0
10.9
0.1
NOTE
MinLoad Control Setpoint is the motor amperage value used to determine when the
bypass valve opens. MinLoad Control Setpoint will always be equal to or greater than
the Throttle Limit value.
CAUTION
The MaxLoad (HLL) value should not exceed the value determined in the
section titled Setting MaxLoad. Failure to set this properly could result in damage to
the motor.
CAUTION
When Surge Indexing is enabled and the compressor surges several times,
the compressor will begin bypassing air sooner than when Surge Indexing is
disabled. You should periodically reset the MinLoad Control Setpoint to prevent
excessive air bypass.
CAUTION
Repeated surging can cause damage to the compressor; therefore, use
caution when desensitizing the Surge Sensitivity setting.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
38
CMC TECHNICAL REFERENCE MANUAL
The Control Parameters Page is
used for matching the control
SETTINGS
SYSTEM
INFO
system to the local application.
PB
IT
D
The Proportional Band (PB),
rep/sec
sec
Integral Time (IT) and Derivative
Inlet Valve
(D) settings are provided for
Pressure
10.0
0.50
0.00
both the inlet valve and bypass
MinLoad (TL)
25.00
0.50
0.00
MaxLoad (HLL)
99.99
0.50
0.00
valves. This gives the controller
Bypass Valve
precise control for modeling the
Pressure
10.0
0.50
0.00
air system over the entire
Load Selected
operating range of the
Remote
3/6
compressor. With this release,
the Derivative constant has
Settings Folder - Page 3: Control Parameters
(PID Settings)
been added to give even more
capability to match the control
system to the air system. However, we recommend that this value remain at zero unless
you have full understanding of how this parameter works.
Loaded
Settings Folder Page 3 Edit Parameters Table
Variable
Minimum
Value
Units
Maximum
Value
Step
Size
Each PB (Proportional Band)
dimensionless
0.0
99.99
0.1
Each It (Integral Band)
repeats/second
0.0
99.99
0.1
Each D (Derivative Band)
seconds
0.0
99.99
0.1
CAUTION
Setting the Derivative parameter to a value other than zero for any of the PID
settings may cause the valve output to change rapidly. Please change this value with
caution.
The Control Mode Selection Page
allows the User to select between
the two standard control modes,
Modulate and Autodual. This
selection process is performed
with the radio button selector. To
change the selection, press the
Up or Down arrow key.
Reload Percent, Unload Point
and Unload Delay Time are all
setpoints for Autodual control.
SYSTEM
INFO
SETTINGS
Control Mode
Manual
Modulate
Autodual
Reload Pressure, % of Setpoint
Unload Point, BV % Open
Unload Delay Timer, seconds
Loaded
98
1
1
Load Selected
Remote
4/6
Settings Folder - Page 4: Control Mode Selection
Checking the Manual checkbox enables manual valve control. In this mode, the inlet valve
may be stroked when the compressor is not running, and the bypass valve can be stroked
22204796 Rev. B, Version 3.10
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CMC TECHNICAL REFERENCE MANUAL
at any time. If a surge condition occurs while manually controlling these valves, the CMC
will automatically take over the valves.
Settings Folder Page 4 Edit Parameters Table
Variable
Units
Minimum
Value
Maximum
Value
Step
Size
1
Autodual Reload Pressure
% of Setpoint
0
99
Autodual Unload Point
BV % Open
1
99
1
Autodual Unload Delay Timer
seconds
0
999
1
CAUTION
Manual should only be used for compressor setup.
Starting Timer is the length of time prior to enabling the loading of the compressor.
Typically, this time includes the starter transition time (Y-D time) and the prelube pump
shutdown. When this timer expires, the prelube pump will turn off and the compressor is
enabled for loading.
Coasting Timer is the length of time that it takes for the driver to stop rotating.
SYSTEM
INFO
SETTINGS
Starting Timer, seconds
Coasting Timer, seconds
CT Ratio
Motor Failure Trip Enable
Inlet Valve Unload Position, %
Setpoint Ramp Rate, pressure/scan
Loaded
20
240
60
15
5.0
Load Selected
Remote
5/6
Settings Folder - Page 5: Miscellaneous
CT Ratio is the ratio of the current
transformer primary to the
secondary; i.e., if the CT primary
winding is 300 and the secondary
winding is 5, then the CT Ratio is
60.
When checked, Motor Failure Trip
Enable tests that the zero_amp
motor_current variable has been
reached after a start command has
been initiated and that motor
current is not lost while the
compressor is running. Uncheck
this box for dry run conditions.
The Inlet Unload Position is the position of the inlet valve when in the unload state.
Setpoint Ramp Rate is used to prevent system pressure overshoot during compressor
loading.
Additional settings will be added to this page for “special” features.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
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CMC TECHNICAL REFERENCE MANUAL
Settings Folder Page 5 Edit Parameters Table
Variable
Minimum
Value
Units
Maximum
Value
Step
Size
Starting Timer
seconds
5
60
1
Coasting Timer
seconds
60
9999
1
CT Ratio
dimensionless
60
9999
1
Inlet Valve Unload Position
percent
0
100
1
Setpoint Ramp Rate
pressure/scan
0
999.9
0.1
WARNING
Failure to set the Coast Timer for a period greater than or equal to the actual
coasting time can result in compressor damage.
The Alarm and Trip Settings Page
provides the means for changing
the analog health monitoring
values. The number of inputs
varies depending upon the number
of compression stages and
optional inputs. Additional pages
will be added as needed after this
page. All line items are changeable
for the Alarm and Trip setpoints.
SYSTEM
INFO
SETTINGS
Stage 1 Temperature
Stage 1 Vibration
Stage 2 Temperature
Stage 2 Vibration
Oil Pressure
High Oil Temperature
Low Oil Temperature
Loaded
Alarm
120
0.80
120
0.75
18
120
100
Trip
125
1.00
125
0.95
16
125
95
Load Selected
Remote
6/6
Settings Folder - Page 6: Alarm and Trip
WARNING
Setting Trip values outside the range specified on the drawings can result in
compressor damage.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
General Sequence of Operation
To start and load a
compressor follow
steps 1, 2, 3 and 4
CENTAC  Microcontroller
SYSTEM
System
Pressure
1
Press
Reset
Pressure
Setpoint
Motor
Current
2 Look for
INFO
SETTINGS
105.3
105.0
173.4
Inlet
Valve
Bypass
Valve
22JUL96
Loaded
"Ready"
95
0
12:00:00
Load Selected
Remote
1/2
3 Press Start
4 Press Load
Press Unload,
5 wait 20 seconds
To unload and stop
a compressor follow
steps 5 and 6
6 Press Stop
Compressor Operating States
Motor
Current
Coasting
Unloaded
Unloading
MaxLoad Setpoint Amps
Motor Full Load Amps
Load
No
Stops or
Trips
MinLoad Setpoint Amps
Any
Stops or
Trips
Start
Unloaded Amps
Zero Amp Offset
0
Power
On
MaxLoad
Loaded
Full Load
Loaded
Unload
Motor Full Load Amps Plus Service Factor
amps, %
100
MinLoad
Loading
Unloaded
Starting
Ready
Not Ready
Waiting
for Motor Driven Packages
Stopped
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Rotating
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CMC TECHNICAL REFERENCE MANUAL
Indicator, Switch and Light Layout
In addition to the CMC OUI there may be a variety of indicators, switches, and lights
mounted on the control panel door. In conjunction with the CMC OUI these devices make
up the User Interface for the CMC. A typical device layout consists of the following lights,
push buttons, and selector switches.
Lights
The lights provided are the green CONTROL POWER ON light, which is integral to the
CONTROL POWER OFF/ON switch, the amber PRELUBE PUMP RUNNING light and the
red TROUBLE INDICATION light.
Push Buttons
The red EMERGENCY STOP push button stops the compressor any time that it is pressed.
This push button is used to initiate a stop in the case of an emergency.
Switches
The CONTROL POWER OFF/ON selector switch turns the panel power on or off
CMC Tuning Procedures
When commissioning a new compressor, troubleshooting an existing compressor, or tuning
a system, the following procedures may be required. The procedures are performed, and
any changes required are made through the CMC OUI. For instructions on how to use the
OUI refer to the section titled User Interface. The following figure will be referenced in the
procedures.
PT
1
PT
2
Bypass
Valve
Pneumatic Tubing
Check
Valve
4-20 mA
Base
Control
Module
CT
Block
Valve
Starter
Motor
Compressor
Plant Air System
4-20 mA
Inlet
Valve
Inlet Filter
Figure 18: Plant Air System
Setting MaxLoad
The MaxLoad Setpoint keeps the motor within the allowable current range. To determine
the value for MaxLoad, an Adjusted Service Factor (ASF) is multiplied by the motor full load
22204796 Rev. B, Version 3.10
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CMC TECHNICAL REFERENCE MANUAL
amps (FLA). The (ASF) is found by obtaining the motor service factor from the motor
nameplate and selecting the adjustment factor from the table below. The motor full load
amps is found on the motor nameplate.
Motor Service Factor
1.15
1.25
Example:
FLA:
Adjusted service factor:
MaxLoad:
Adjusted Service Factor
1.05
1.10
MaxLoad = FLA X ASF
134 Amps
1.05
140
Setting MinLoad
MinLoad establishes the minimum flow through the machine when loaded; it is the
maximum point of inlet valve throttling. If system demand is below this throttle point, the
compressor must bypass air or unload. If flow were allowed to go below MinLoad, the
machine would eventually cross the surge line and surge. By stopping inlet valve throttling
at MinLoad the machine is kept out of surge. To find the MinLoad setting, the machine is
run into the surge line, and the value of load (amps, kilowatts, SCFM) at surge is recorded.
The recorded value is then incremented by five percent and set as the value for MinLoad.
1. Before continuing this procedure, verify the following:
a) The inlet and bypass control valves have been calibrated.
b) The machine is running unloaded.
c) The block valve at the inlet to the plant air system (Figure 18) is closed.
d) The pressure setpoint is set to the pressure at which the machine is going to
operate.
2. Set initial MinLoad estimates.
a) In the Settings Folder, select the Edit Data cell for MinLoad.
b) Increment or decrement the value to achieve a value of approximately 95% of full
load amps.
3. Preset the manual bypass valve position to 100.
a) On the OUI select the Settings Folder and enable manual valve control by
highlighting the manual check box.
NOTE
When Manual is enabled, both control valves can be positioned while stopped, while
only the Bypass Valve can be positioned when Loaded.
b) Switch to the System Folder Page 1 and press the Enter Key to enable edit mode.
c) Use the horizontal navigation keys to select the bypass valve.
22204796 Rev. B, Version 3.10
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CMC TECHNICAL REFERENCE MANUAL
d) Increment the value to position the valve to 100 percent.
4. Load the compressor by pressing the Load Key.
5. Find the throttled surge point.
a) Slowly decrement the bypass valve position until the last stage discharge pressure
equals the pressure setpoint.
b) Allow the system to stabilize at MinLoad. It the system does not stay at MinLoad,
slightly decrement the valve position to force the machine to throttle to MinLoad.
c) Decrement (MinLoad) 2%.
d) Verify the last stage pressure equals the pressure setpoint and adjust the bypass
valve position if necessary.
e) Repeat c) and d) until the compressor surges.
6. Increase MinLoad by five percent.
7. Exit MinLoad editing by pressing the Enter Key.
8. Unload the machine.
9. Disable manual valve control by unchecking the manual check box.
Setting MinLoad Surge Index Increment
When Surge Indexing is enabled (MinLoad Surge Index Increment is greater than zero), the
Index Increment value is the amount added to the MinLoad Control Setpoint upon a surge.
The MinLoad Control Setpoint will stop being incremented when and if the value reaches
MaxLoad.
Setting Surge Sensitivity
The Surge Sensitivity setting should be set sensitive enough to detect a surge, yet not
trigger on spurious noise in the system. To set the surge sensor the machine is forced to
surge by running the machine at MinLoad and the MinLoad setpoint is dropped until the
machine audibly surges. The process is repeated until the correct setting is found.
1. Before continuing this procedure, verify the following:
a) The plant can tolerate a pressure disturbance when the machine surges.
b) Surge Indexing (by placing MinLoad Surge Index Increment to zero) is disabled.
c) Surge Absorber is disabled.
d) The pressure setpoint is set to the pressure at which the machine is going to
operate.
e) The machine is running unloaded.
2. Set the initial Surge Sensitivity setting to 9.
a) In the Settings Folder, select the Edit Data cell for Surge Sensitivity.
b) Increment or decrement the value to achieve a setting of 9.
3. Press the Load Key.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
4. Run the compressor at MinLoad and system pressure setpoint pressure. The
machine can be forced to MinLoad and to maintain system pressure setpoint by either.
a) Running the plant at a higher pressure than pressure setpoint.
b) Decreasing load in the plant.
c) Verify the compressor is at pressure by observing the last stage pressure on
Page 2 of the Settings Folder.
5. Find the throttled surge point.
a) Select the MinLoad cell in the Settings Folder and slowly decrement the value until
the machine surges. Typically the machine will make a puffing or popping noise
upon surge, this is your indication surge has occurred.
6. Press the Unload Key.
7. Determine if Surge was recorded.
a) Inspect the Status Bar. If the message Surge Unload is displayed surge was
recorded, if the message is not displayed surge was not recorded.
8. Check the Surge Sensitivity setting.
a) If the surge was recorded, the setting may be correct or the Surge Sensor may be
too sensitive, skip to the too sensitive step, which follows.
b) If the surge was not recorded, the setting is not sensitive enough, skip to the not
sensitive enough step, which follows.
9. Surge Sensor too sensitive.
a) Select the Surge Sensitivity Setting in the Settings Folder.
b) Decrease the value for Surge Sensitivity by 0.1.
c) Press the Reset Key.
d) Skip to step 11.
10. Surge Sensor not sensitive enough.
a) Select the Surge Sensitivity Setting in the Settings Folder.
b) Increase the value for Surge Sensitivity by 0.1.
c) Press the Reset Key.
11. Repeat the procedure until the Surge Sensitivity setting is found which just catches a
surge but does not miss a surge.
a) Return to step 3.
12. Restore MinLoad value.
Tuning Stability
The CMC controls stability with four Proportion Integral Derivative (PID) control loops.
When the machine is running above the MinLoad point and below the MaxLoad point,
pressure is regulated with the Inlet Valve Pressure control loop. When the machine is
running at the MinLoad point, pressure is regulated with the Bypass Valve Pressure control
22204796 Rev. B, Version 3.10
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CMC TECHNICAL REFERENCE MANUAL
loop and motor current is regulated with the Inlet Valve MinLoad control loop. When the
machine is running at MaxLoad motor current is regulated with the Inlet Valve MaxLoad
control loop. For each PID loop, Proportional, Integral and Derivative parameters are used
to stabilize the system. For a definition of the parameters and their effect on stability, refer
to the section titled “How does Constant Pressure Modulation Work.” The proportional and
integral terms are labeled by their respective loops, Inlet Valve, Bypass Valve, MinLoad,
and MaxLoad.
Calibrating the Control Valves
The purpose of this procedure is to position the inlet and bypass valves by opening and
closing each valve from the CMC analog outputs. The valves should be adjusted to
physically correspond with the valve positions displayed on the OUI.
1.
Stop the compressor.
NOTE
Performing this procedure while the compressor is operating may cause serious
damage.
2.
On the OUI enable Setpoint changes by entering the password on the Settings Folder.
3.
Verify the OUI status bar displays “Ready” or “Not Ready”.
4.
On the OUI select the Settings Folder and enable manual valve control by highlighting
the manual check box.
NOTE
When Manual is enabled, both control valves can be positioned while stopped, while
only the Bypass Valve can be positioned when Loaded.
5.
Switch to the System Folder Page 1 and press the Enter Key to enable edit mode.
6.
Use the horizontal navigation keys to select the valve requiring positioning.
7.
Use the vertical arrows to increment and decrement the valve position sent to the
valve.
NOTE
For the Inlet and Bypass Valves, the displayed position corresponds to percent open.
8.
Disable manual valve control by blanking the manual check box.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
Autodual Control Settings
For a detailed definition of the Autodual control mode refer to the section titled “Control
Methodology”. The procedure for tuning Autodual requires the setting of the following
variables:
Unload Point (Bypass Valve % Open)
The Bypass Valve Unload Point is selected to correspond to the check valve closing as
shown in Figure 18, since at this point the machine is not supplying the system. This
position is found by running the machine at MinLoad and monitoring the System and
Discharge pressures. When the System pressure is 5% of setpoint greater than the last
stage pressure as shown in the System Folder, the check valve is assumed to be closed.
Example: Given the following conditions the Unload Point would be set at 35.
Variable
Pressure Setpoint
PT1 (system pressure)
PT2 (last stage pressure)
Bypass Valve Position
Assumed check valve position
Case 1
100
100
100
13
Open
Case 2
100
100
94
35
Closed
1. Run the machine at MinLoad by elevating the system pressure no more than 3% or
decrease the pressure setpoint no more than 3%.
2. Monitor the difference between the Discharge and System Pressures by using the
System Folder Pages 1 and 2.
3. When the Discharge Pressure is approximately 95% of setpoint, record the Bypass
Valve Position.
4. Enter the recorded Bypass Valve Position as the Unload Point.
Unload Delay Time (seconds)
The Unload Delay Timer should be set to prevent unloading during short excursions
through the Unload Point. Typically, when the check valve closes, system demand requires
the check valve to open again soon thereafter due to the demand being on the verge of
requiring the compressor. If the compressor had unloaded when the check valve first
closed, a reload would be immediately required and the machine would go through the
automatic unload/load cycle until demand was consistently low enough to keep the check
valve closed. For this reason, the timer is used to inhibit Unload until demand has
consistently remained low. This value should be set according to the customer’s
observation experience as to how often system demand changes impact the reloading of
the compressor.
Reload Percent
The Reload Percent determines the System Pressure at which the machine will
automatically load into the system. This value should be set according to the customer’s
minimum acceptable system pressure.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
Setting the Start Time
The Start Time is set to the transition time of a built-in reduced voltage starter or the
acceleration time of a customer supplied starter. This procedure requires the Inlet Unload
Position to have been set.
CAUTION
Damage to the starter contacts could result if starter transition occurs before
the compressor is up to full speed.
1.
Initially set the Start Time to 25 Seconds.
2.
Stop the compressor. Allow compressor to coast to a stop.
3.
On the OUI record the time and press the start button.
4.
Wait for the compressor to stop accelerating and again record the time.
5.
Calculate the difference between the two values and enter as the Start Time.
Setting the CT Ratio
Locate the CT and find the rating, which is typically printed, on the side of the CT. Divide
the primary by the secondary and enter the value as the CT Ratio.
Example: CT is printed with 600:5, the value entered is 120.
Inlet Unload Position
The purpose of this variable is to set the inlet valve position when the machine is running
unloaded. For a description of the Unloaded state refer to the section titled “Unload”.
1.
If the inlet valve is a butterfly type, enter an initial value for Inlet Unload Position of 15. If
the inlet valve is a inlet guide vane type, enter an initial value for Inlet Unload Position of
5.
2.
Start the machine. If during startup the motor trips on overload, draws what is
considered excessive amperage or sounds labored, stop the machine and decrease the
Unload Position by 2 and restart the machine.
3.
Run the machine in the Unloaded state and monitor the first stage pressure.
4.
Adjust the Unload Position to achieve 1 PSIG on the first stage discharge, or until a
positive pressure is felt at the first stage condensate trap bypass.
5.
If the inlet air temperature is relatively cold, increase the setting 2%, this will
accommodate hot day operation.
Setting Set Point Ramp Rate
Setpoint ramp rate determines the rate at which the machine transitions from unloaded to
loaded. The setting should be set as high as possible without creating excessive overshoot
when the machine enters the system.
1.
Verify the machine is unloaded by the “Unloaded” message in the OUI Status Bar.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
2.
3.
4.
5.
Determine overshoot.
a)
Load the machine.
b)
Monitor the pressure overshoot.
If overshoot is excessive.
a)
Decrease the Setpoint Ramp Rate.
b)
Repeat step 2.
If overshoot is satisfactory and time to load is excessive.
a)
Increase the Setpoint Ramp Rate.
b)
Repeat step 2.
If overshoot is satisfactory and time to load is satisfactory the Setpoint Ramp Rate is
correct.
Alarm and Trip Settings
The values for vibration, temperature, pressure etc. alarm and trip setpoints are located on the
electrical schematic. These values determine when the controller will indicate an alarm or trip
condition.
WARNING
Setting Trip values outside the range specified on the drawings can result in
compressor damage.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
Troubleshooting
The following procedures provide direction on troubleshooting the CMC System, control
panel, and associated instrumentation. Faults are either Event Logged, which means the
fault is displayed in the INFO Folder on the OUI, or Non-Event Logged. The distinction
helps to expedite the troubleshooting process.
When a control system fault is suspected, the following diagram is used to categorize the
fault. The section following the diagram breaks each category down into specific items,
which can cause a particular fault.
A CONTROL
SYSTEM FAULT IS
SUSPECTED
THE FAULT IS LOGGED IN
THE EVENT LOG.
COMPRESSOR RELATED
I/O FAULT
Event correctly indicates a problem.
Temperature, pressure, load, valve, etc.
readings incorrect.
(Refer to the compressor operating manual)
THE FAULT IS NOT LOGGED IN
THE EVENT LOG
CONTROL PROBLEMS
Compressor fails to Load, fails to trip, fails to
start, surging, etc.
(Refer to the CMC Tuning Procedures section)
(Refer to the Input/Output (I/O) System)
STABILITY PROBLEMS
CONTROLLER PROBLEMS
Inlet valve, bypass valve, or control variables
(mass flow, system pressure, Kw, amps) are
unstable.
OUI failed, BCM failed, UCM failed,
Communications failed.
(Refer to Controller Problems Section)
(Refer to the CMC Tuning Procedures Section)
Figure 19: Troubleshooting Tree
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
Troubleshooting Example
The following example will serve as a guide to follow when troubleshooting specific
problems.
Problem Indication:
Plant air pressure is low and the CMC OUI is found
as shown.
Probable Cause Determination:
1.
SYSTEM
1
2
3
4
5
6
7
INFO
SETTINGS
Event Name
Low Oil Pressure Trip
Low Oil Pressure Alarm
Reset key pressed
Low Oil Pressure Trip
Low Oil Pressure Alarm
Load key pressed
Start key pressed
Not Ready
Time
Date
09:18:44 0720
09:18:43 0720
09:18:34 0720
09:08:43 0720
08:58:23 0720
08:24:01 0720
08:23:12 0720
Trip
Remote
2/6
The machine Tripped on Low Oil Pressure, which means the oil pressure, was below
the Oil Pressure Trip Value. Figure 19 leads to the assumption that the problem is
either compressor or I/O related, because the fault is Event Logged. There are two
most likely causes for this event.
a) Actual oil pressure is low.
i)
The prelube pump is found to be running and installation of a calibrated
pressure sensor shows the actual oil pressure to be above the Oil Pressure Trip
Value. Therefore, the mechanical system is operating correctly.
b) The value read by the CMC is incorrect.
i)
The oil pressure value displayed on Page 2 of the System Folder shows the oil
pressure to be below the test sensor reading and erratic. Additionally, all other
analog input readings are normal and not erratic. Therefore, the problem can be
isolated to the oil pressure, analog input circuit.
ii)
The Pressure Monitoring System (PMS) troubleshooting table, found in the
following section “The Pressure Monitoring System” identifies the probable
cause for an erratic reading as a loose wire/terminal/connector and specifies
Troubleshooting Procedure PMS #1 and 2 as the appropriate procedures.
Trouble Procedure Execution:
Step 1 of PMS #1 requires disconnecting of the pressure transducer (PT) wires at the
terminal strip. When this step is performed, one of the connections is found to be
intermittent. When the poor connection is corrected, the erratic reading on the OUI
becomes solid.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
Input/Output (I/O) System
Vibration Monitoring System (VMS)
Description:
The vibration transmitter is used to convert the proximity probe signal into a 4 -20 mA
signal, which is monitored by the CMC. The system is based on a 5 meter total electrical
length (vibration probe electrical length plus extension cable electrical length).
Component specifications: (5 meter)
Transmitter:
•
200 mv/mil = 0.2 volt per 0.001 in (0.0254 mm)
•
4 mil (0.1016 mm) scale
•
4-20 mA output
Probe:
•
Gap setting 0.030 to 0.060 in (0.762 to 1.524 mm), see Service Hints for nominal gap
•
Probe gap corresponds to 6 to 12 volts VDC
•
Ohm value of 0.5 meter Probe is 4 ohms, +/- 0.5 ohm
Troubleshooting:
The following table identifies typical problems, probable causes, and appropriate
procedures for verifying the probable cause:
Typical Problem
Zero OUI readout
(when compressor is
running)
Erratic OUI readout
Incorrect OUI readout
Probable Cause
Open circuit/cable disconnected
Loss of power to transmitter
Malfunctioning transmitter
Transmitter not calibrated
Loose wire/terminal/connector
Any
Troubleshooting Procedure
VMS #2, 3, 4
VMS #1
VMS #2
VMS #2
VMS #2, 3, 4
VMS #1, 2, 3, 4, 5
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
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CMC TECHNICAL REFERENCE MANUAL
Checking Vibration Transmitter Power
VMS #1
1. Connect a DC voltmeter to the +
and
terminals
of
the
transmitter.
2. With control power on, there
should be approximately 24
VDC present at the terminals.
3. If approximately 24 VDC is not
present; see the section titled
“Control Power System”.
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
VDC
mA
VAC
Ω
mA COM V Ω
NOTE: Under no circumstances
should the vibration transmitter zero
or span be adjusted. Calibration of
the vibration transmitter requires
special tooling and calibration
fixtures. Contact the factory if
calibration is required.
(See electrical
schematic for point).
Vibration
transmitter
Checking Vibration Circuit
1. With control power on, check the dc
voltage at the COM and TEST terminals
on the transmitter. A reading of 6 to 12
VDC should be present [this corresponds
to a 0.030 to 0.060 inches (0.762 to
1.524 mm)] probe gap.
2. If less than 6 volts is present the probe
gap may be incorrect, or a short circuit
may exist. Check the cable connections
and cable.
3. If more than 12 volts is present the probe
gap may be incorrect, or an open circuit
may exist. Check the cable connections
and cable.
4. If no voltage exists, the transmitter may
be faulty. Remove control power and
swap connections with another
transmitter and test.
VMS #2
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
VDC
mA
VAC
Ω
mA COM V Ω
Compressor casing
Vibration transmitter
Vibration probe
Probe extension cable
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
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CMC TECHNICAL REFERENCE MANUAL
Check the Vibration Probe, and Cable
VMS #3
1. Turn control power off and disconnect
the probe extension cable from the
transmitter.
2. Check resistance of the extension cable
and probe together, the reading should
be 5.3 ohms, +/- 0.7 ohm (5 meter
system)
Probe connector
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
VDC
mA
VAC
Ω
Probe cable
mA COM V Ω
Compressor
casing
Connect test lead
to outer shell.
Connect test lead
to inner pin.
Probe extension
cable
Vibration probe
Checking the Vibration Probe
1. Turn control power off and disconnect
the probe extension cable from the
transmitter.
2. Check resistance of the probe alone, the
reading should be 4.0 ohms, +/- 0.5 ohm
(0.5 meter probe)
VMS #4
Connect test lead
to outer shell.
XXXXX
XXXXX
XXXXX
XXXXX
Probe connector
XXXXX
XXXXX
VDC
mA
VAC
Ω
Probe cable
mA COM V Ω
Vibration probe
Connect test lead
to inner pin.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
55
CMC TECHNICAL REFERENCE MANUAL
Check the BCM
VMS #5
1. With control power off connect a 4-20 mA simulator at the input points of the suspected
faulty device at connector J1, (see electrical schematic for connection points).
2. Turn control power on and vary the signal. If the value tracks according to the table
below, the wiring is faulty.
3. Verify the connector at J1 is fully seated. If the value does not track correctly, the BCM
may be faulty.
BCM
J2-Floating Analog Inputs, (4-20mA) Channels 1-2
J1-Grounded Analog Inputs,
(4-20mA) Channels 3-23
Pin 25
Pin 1
4-20 mA SURCE OR
2 WIRE SIMULATOR
LOOP
ON
DIAL
100%
BATTERY
CHECK
OFF
2 WIRE
mA OUT
00.0% - 100%
00.0%
XXXXXX
MODEL CL-XXX
555
mA percent
(from simulator)
100%
50%
0%
Conversion chart
Mils
(on OUI)
4.0
2.0
0.0
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
mA
(from simulator)
20
12
4
56
CMC TECHNICAL REFERENCE MANUAL
Temperature Monitoring System (TMS)
Description:
An RTD (Resistance Temperature Detector-2 Wire) with external transmitter is used by the
CMC for temperature monitoring. An RTD resistance (ohmic value) varies with temperature.
A transmitter for monitoring by the CMC analog input channel converts the resistance to a
4-20 mA signal.
Component specification:
Probe:
•
100 ohm Platinum resistance at 32 °F (0°C) with Temperature Coefficient Rating (TCR)
of 0.00385 Ohm/Ohm/Deg C
Transmitter:
•
The transmitter may be mounted in the RTD connection head fitting or in the control
panel enclosure. The transmitter is supplied 24 VDC and outputs 4-20mA over a fixed
range of either 0 to 200°F (-17.7 to +93.3°C), or 0-500°F (-17.7 to +260°C).
Troubleshooting:
The following table identifies typical problems, probable causes, and appropriate
procedures for verifying the probable cause:
Typical Problem
High OUI readout
Probable Cause
High resistance connection
Transmitter not calibrated
RTD failure
Transmitter failure
Low OUI readout
Transmitter failure
RTD failure
Transmitter not calibrated
Erratic OUI readout
Loose terminal connection
RTD internal wire fault
Transmitter failure
Incorrect OUI readout Transmitter not calibrated
RTD or transmitter failure
Any
Troubleshooting
Procedure
TMS #4
TMS #3
TMS #2
TMS #3
TMS #3
TMS #2
TMS #3
TMS #4
TMS #2
TMS #3
TMS #3
TMS #2, 3
TMS #1, 2, 3, 4
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
57
CMC TECHNICAL REFERENCE MANUAL
Checking for Power to the Temperature Transmitter
TMS #1
1. Disconnect the wires at terminals #1 and #2 on the transmitter and connect a voltmeter
to these wires.
2. With control power on, there should be approximately 24 VDC present at the terminals.
3. If approximately 24 VDC is not present, see the section titled “Control Power System”.
BCM
J2-Floating Analog Inputs, (4-20mA) Channels 1-2
J1-Grounded Analog Inputs,
(4-20mA) Channels 3-23
Pin 25
Pin 1
XXXXX
XXXXX
XXXXX
XXXXX
VDC
XXXXX
XXXXX
mA
123 4
VAC
Ω
mA COM V Ω
RTD
Temperature transmitter
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
58
CMC TECHNICAL REFERENCE MANUAL
Checking for a Faulty RTD
TMS #2
1. Turn control power off.
2. Check ohms versus temperature. Use an
Ohmmeter and the following tables to
determine if the RTD is faulty. Vary the
temperature to the RTD and check the
ohms around the normal operating
range.
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
VDC
mA
VAC
Ω
mA COM V Ω
Thermometer
RTD
32 DEGF
Ice water
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
59
CMC TECHNICAL REFERENCE MANUAL
Degrees Fahrenheit versus Ohms value chart for 100 OHM Platinum RTD
°F
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340
350
360
370
380
390
400
410
420
430
440
450
460
470
480
490
500
0
93.01
95.20
97.38
99.56
101.70
103.90
106.10
108.20
110.40
112.50
114.70
116.80
119.00
121.10
123.20
125.40
127.50
129.60
131.70
133.90
136.00
138.10
140.20
142.30
144.40
146.50
148.60
150.70
152.70
154.80
156.90
159.00
161.00
163.10
165.20
167.20
169.30
171.30
173.40
175.40
177.50
179.50
181.50
183.60
185.60
187.60
189.70
191.70
193.70
195.70
197.70
1
93.22
95.42
97.60
99.78
102.00
104.10
106.30
108.40
110.60
112.70
114.90
117.00
119.20
121.30
123.40
125.60
127.70
129.80
132.00
134.10
136.20
138.30
140.40
142.50
144.60
146.70
148.80
150.90
153.00
155.00
157.10
159.20
161.30
163.30
165.40
167.40
169.50
171.50
173.60
175.60
177.70
179.70
181.80
183.80
185.80
187.80
189.90
191.90
193.90
195.90
197.90
2
93.44
95.63
97.82
100.00
102.20
104.30
106.50
108.70
110.80
113.00
115.10
117.30
119.40
121.50
123.60
125.80
127.90
130.00
132.20
134.30
136.40
138.50
140.60
142.70
144.80
146.90
149.00
151.10
153.20
155.20
157.30
159.40
161.50
163.50
165.60
167.60
169.70
171.80
173.80
175.80
177.90
179.90
182.00
184.00
186.00
188.00
190.10
192.10
194.10
196.10
198.10
3
93.66
95.85
98.04
100.20
102.40
104.60
106.70
108.90
111.00
113.20
115.30
117.50
119.60
121.70
123.90
126.00
128.10
130.30
132.40
134.50
136.60
138.70
140.80
142.90
145.00
147.10
149.20
151.30
153.40
155.40
157.50
159.60
161.70
163.70
165.80
167.80
169.90
172.00
174.00
176.00
178.10
180.10
182.20
184.20
186.20
188.20
190.30
192.30
194.30
196.30
198.30
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
4
93.88
96.07
98.26
100.40
102.60
104.80
106.90
109.10
111.20
113.40
115.50
117.70
119.80
122.00
124.10
126.20
128.30
130.50
132.60
134.70
136.80
138.90
141.00
143.10
145.20
147.30
149.40
151.50
153.60
155.70
157.70
159.80
161.90
163.90
166.00
168.10
170.10
172.20
174.20
176.30
178.30
180.30
182.40
184.40
186.40
188.40
190.50
192.50
194.50
196.50
198.50
5
94.10
96.29
98.47
100.70
102.80
105.00
107.10
109.30
111.50
113.60
115.80
117.90
120.00
122.20
124.30
126.40
128.60
130.70
132.80
134.90
137.00
139.10
141.20
143.30
145.40
147.50
149.60
151.70
153.80
155.90
157.90
160.00
162.10
164.10
166.20
168.30
170.30
172.40
174.40
176.50
178.50
180.50
182.60
184.60
186.60
188.60
190.70
192.70
194.70
196.70
198.70
6
94.32
96.51
98.69
100.90
103.00
105.20
107.40
109.50
111.70
113.80
116.00
118.10
120.20
122.40
124.50
126.60
128.80
130.90
133.00
135.10
137.20
139.30
141.40
143.50
145.60
147.70
149.80
151.90
154.00
156.10
158.10
160.20
162.30
164.30
166.40
168.50
170.50
172.60
174.60
176.70
178.70
180.70
182.80
184.80
186.80
188.80
190.90
192.90
194.90
196.90
198.90
7
94.54
96.73
98.91
101.10
103.30
105.40
107.60
109.70
111.90
114.00
116.20
118.30
120.50
122.60
124.70
126.90
129.00
131.10
133.20
135.30
137.40
139.60
141.70
143.80
145.90
147.90
150.00
152.10
154.20
156.30
158.40
160.40
162.50
164.60
166.60
168.70
170.70
172.80
174.80
176.90
178.90
180.90
183.00
185.00
187.00
189.00
191.10
193.10
195.10
197.10
199.10
8
94.76
96.95
99.13
101.30
103.50
105.60
107.80
109.90
112.10
114.30
116.40
118.50
120.70
122.80
124.90
127.10
129.20
131.30
133.40
135.50
137.70
139.80
141.90
144.00
146.10
148.20
150.20
152.30
154.40
156.50
158.60
160.60
162.70
164.80
166.80
168.90
170.90
173.00
175.00
177.10
179.10
181.10
183.20
185.20
187.20
189.20
191.30
193.30
195.30
197.30
199.30
9
94.98
97.17
99.35
101.50
103.70
105.80
108.00
110.20
112.30
114.50
116.60
118.80
120.90
123.00
125.20
127.30
129.40
131.50
133.60
135.80
137.90
140.00
142.10
144.20
146.30
148.40
150.50
152.50
154.60
156.70
158.80
160.80
162.90
165.00
167.00
169.10
171.10
173.20
175.20
177.30
179.30
181.30
183.40
185.40
187.40
189.40
191.50
193.50
195.50
197.50
199.50
60
CMC TECHNICAL REFERENCE MANUAL
Degrees Celsius versus Ohms value chart for 100 OHM Platinum RTD
°C
-17.78
-12.22
-6.67
-1.11
4.44
10.00
15.56
21.11
26.67
32.22
37.78
43.33
48.89
54.44
60.00
65.56
71.11
76.67
82.22
87.78
93.33
98.89
104.44
110.00
115.56
121.11
126.67
132.22
137.78
143.33
148.89
154.44
160.00
165.56
171.11
176.67
182.22
187.78
193.33
198.89
204.44
210.00
215.56
221.11
226.67
232.22
237.78
243.33
248.89
254.44
260.00
0.00
93.01
95.20
97.38
99.56
101.74
103.90
106.07
108.22
110.38
112.53
114.68
116.83
118.97
121.11
123.22
125.37
127.50
129.62
131.74
133.86
135.97
138.08
140.18
142.29
144.39
146.48
148.57
150.66
152.74
154.82
156.90
158.98
161.05
163.11
165.17
167.23
169.29
171.34
173.39
175.44
177.48
179.51
181.55
183.58
185.60
187.63
189.65
191.67
193.68
195.69
197.69
0.62
93.22
95.42
97.60
99.78
101.95
104.12
106.28
108.44
110.60
112.75
114.89
117.04
119.18
121.32
123.43
125.58
127.71
129.83
131.95
134.07
136.18
138.29
140.39
142.50
144.59
146.69
148.78
150.87
152.95
155.03
157.11
159.18
161.25
163.32
165.38
167.44
169.49
171.55
173.59
175.64
177.68
179.72
181.75
183.78
185.81
187.83
189.85
191.87
193.88
195.89
197.89
1.23
93.44
95.63
97.82
100.00
102.17
104.34
106.50
108.66
110.81
112.96
115.11
117.25
119.39
121.53
123.65
125.79
127.92
130.04
132.16
134.28
136.39
138.50
140.60
142.71
144.80
146.90
148.99
151.08
153.16
155.24
157.32
159.39
161.46
163.52
165.59
167.64
169.70
171.75
173.80
175.84
177.88
179.92
181.95
183.98
186.01
188.03
190.05
192.07
194.08
196.09
198.09
1.85
93.66
95.85
98.04
100.22
102.39
104.55
106.71
108.87
111.03
113.18
115.32
117.47
119.61
121.75
123.87
126.01
128.13
130.26
132.38
134.49
136.60
138.71
140.81
142.92
145.01
147.11
149.20
151.28
153.37
155.45
157.52
159.60
161.67
163.73
165.79
167.85
169.90
171.96
174.00
176.05
178.09
180.12
182.16
184.19
186.21
188.24
190.25
192.27
194.28
196.29
198.29
2.47
93.88
96.07
98.26
100.43
102.60
104.77
106.93
109.09
111.24
113.39
115.54
117.68
119.82
121.96
124.08
126.22
128.35
130.47
132.59
134.70
136.81
138.92
141.02
143.13
145.22
147.32
149.41
151.49
153.58
155.66
157.73
159.80
161.87
163.94
166.00
168.06
170.11
172.16
174.21
176.25
178.29
180.33
182.36
184.39
186.41
188.44
190.46
192.47
194.48
196.49
198.49
3.09
94.10
96.29
98.47
100.65
102.82
104.98
107.14
109.30
111.46
113.61
115.75
117.90
120.04
122.17
124.30
126.43
128.56
130.68
132.80
134.91
137.02
139.13
141.24
143.34
145.43
147.53
149.61
151.70
153.78
155.86
157.94
160.01
162.08
164.14
166.20
168.26
170.32
172.37
174.41
176.46
178.49
180.53
182.56
184.59
186.62
188.64
190.66
192.67
194.68
196.69
198.70
3.70
94.32
96.51
98.69
100.87
103.04
105.20
107.36
109.52
111.67
113.82
115.97
118.11
120.25
122.39
124.51
126.65
128.77
130.89
133.01
135.12
137.24
139.34
141.45
143.55
145.64
147.73
149.82
151.91
153.99
156.07
158.15
160.22
162.29
164.35
166.41
168.47
170.52
172.57
174.62
176.66
178.70
180.73
182.77
184.80
186.82
188.84
190.86
192.87
194.88
196.89
198.90
4.32
94.54
96.73
98.91
101.08
103.25
105.42
107.58
109.73
111.89
114.04
116.18
118.32
120.46
122.60
124.73
126.86
128.98
131.10
133.22
135.34
137.45
139.55
141.66
143.76
145.85
147.94
150.03
152.12
154.20
156.28
158.35
160.42
162.49
164.56
166.62
168.67
170.73
172.78
174.82
176.86
178.90
180.94
182.97
185.00
187.02
189.04
191.06
193.08
195.09
197.09
199.10
4.94
94.76
96.95
99.13
101.30
103.47
105.63
107.79
109.95
112.10
114.25
116.40
118.54
120.68
122.81
124.94
127.07
129.20
131.32
133.43
135.55
137.66
139.76
141.87
143.97
146.06
148.15
150.24
152.33
154.41
156.49
158.56
160.63
162.70
164.76
166.82
168.88
170.93
172.98
175.03
177.07
179.11
181.14
183.17
185.20
187.22
189.25
191.26
193.28
195.29
197.29
199.30
5.56
94.98
97.17
99.35
101.52
103.69
105.85
108.01
110.16
112.32
114.47
116.61
118.75
120.89
123.03
125.16
127.28
129.41
131.53
133.65
135.76
137.87
139.97
142.08
144.18
146.27
148.36
150.45
152.54
154.62
156.69
158.77
160.84
162.91
164.97
167.03
169.08
171.14
173.19
175.23
177.27
179.31
181.35
183.38
185.40
187.43
189.45
191.46
193.48
195.49
197.49
199.50
NOTE: This chart converted from Fahrenheit chart using formula °C= ((°F-32)/1.8)
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
61
CMC TECHNICAL REFERENCE MANUAL
Checking the RTD Transmitter
TMS #3
1. With control power off, connect a 100-ohm resistor to terminals #3 and #4 of the
transmitter.
2. Turn control power on, the OUI reading should be 32°F (0°C) ±5%.
3. If the reading is not within specification, the transmitter may be faulty.
BCM
J2-Floating Analog Inputs, (4-20mA) Channels 1-2
J1-Grounded Analog Inputs,
(4-20mA) Channels 3-23
Pin 25
Pin 1
100
123 4
OHM
5%
Temperature transmitter
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
62
CMC TECHNICAL REFERENCE MANUAL
Checking proper operation of the BCM and wiring
TMS #4
1. Ensure control power is off. At the affected RTD transmitter, disconnect the wires at
transmitter terminal #1 and #2. Connect a 4-20mA source to these terminals (Observe
correct polarity). Power up the control panel and then vary the simulator output.
2. At 12 mA (50%) the OUI should read 1/2 the RTD transmitter range; 100 or 250°F (37.7
or 121.1°C). The readout should change as the simulator output is varied.
3. If the reading on the OUI is incorrect or does not change, turn control power off and
reconnect the transmitter, remove the wires for this transmitter from J1 and move the 4
to 20 mA simulator to the respective terminals at connector J1, (see electrical schematic
for connection points).
4. Turn control power on and observe the OUI readout while varying the 4-20mA. If the
reading is correct there is an open or short in the wire or terminals connecting the CMC
to the RTD transmitter. If reading is not correct the BCM may be faulty.
BCM
J2-Floating Analog Inputs, (4-20mA) Channels 1-2
J1-Grounded Analog Inputs,
(4-20mA) Channels 3-23
Pin 25
Pin 1
4-20 mA SURCE OR
2 WIRE SIMULATOR
LOOP
ON
DIAL
100%
BATTERY
CHECK
OFF
2 WIRE
mA OUT
00.0% - 100%
00.0%
XXXXXX
MODEL CL-XXX
555
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
63
CMC TECHNICAL REFERENCE MANUAL
Valve Control System (VCS)
Description:
The BCM generates a 4-20 mA signal for valve control. The signal is wired to the I/P
(current to pressure) transducer for conversion to a pneumatic signal for positioning the
inlet or bypass control valve.
Specification:
•
4-20mA input = 3 to 15 psi output
•
60 to 120 PSIG instrument air input to I/P
Troubleshooting:
The following table identifies typical problems, probable causes, and appropriate
procedures for verifying the probable cause:
Typical Problem
IV or BV not operating
Probable Cause
Failure of BCM
Positioner or actuator malfunction
Failure of I/P
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Troubleshooting Procedure
VCS #1
VCS #2
VCS #2
64
CMC TECHNICAL REFERENCE MANUAL
Checking proper operation of the BCM and wiring
VCS #1
1. With control power off, lift the wires at J3 for the suspected circuit and install a test meter
capable of reading milliamps as shown below, (the pin numbers are found on the
electrical schematic).
2. Restore control power.
3. If the meter reads 4 mA , the BCM is satisfactory.
4. If 4 mA is not present, refer to the section titled “Control Power System”.
5. Restore connections.
6. Remove control power.
7. Lift wires at suspected I/P, and install meter as in previous step.
8. Restore control power.
If the meter reads 4 mA, the BCM and wiring is satisfactory.
BCM
J3-Analog Outputs, (4-20mA) Channels 1-4
J1-Grounded Analog Inputs,
(4-20mA) Channels 3-23
Pin 25
Pin 1
Pin 1
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
VDC
mA
VAC
Ω
mA COM V Ω
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
65
CMC TECHNICAL REFERENCE MANUAL
Checking proper operation of the I/P and positioner
VCS #2
1. Connect a 4-20 mA simulator to the I/P.
2. Ensure instrument air is present at the supply connection on the I/P.
3. Vary the simulator between 4-20 mA. The output of the I/P and the positioner should
follow. If the valve tracks the 4-20 mA signal correctly the I/P and the positioner are
satisfactory.
BATTERY
CHECK
LOOP
ON
mA OUT
100%
OFF
DIAL
2 WIRE
00.0%
XXXXXX
MODEL CL-XXX
4-20 mA SURCE OR
2 WIRE SIMULATOR
00.0% - 100%
555
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
INGERSOLL-RAND
Centrifugal Compressor Division
Highway 45 South
Mayfield, KY. 42066
Parts Service (800) 247-8640
66
CMC TECHNICAL REFERENCE MANUAL
Pressure Monitoring System (PMS)
Description:
A Pressure Transducer (PT) is used to convert pressure (psi) to a 4-20 mA signal for
monitoring by the CMC.
Component specification:
•
0-50 PSIG (344.75 kPa) range
•
0-200 PSIG (1379 kPa) range
•
Power = 24 VDC
Troubleshooting:
The following table identifies typical problems, probable causes, and appropriate
procedures for verifying the probable cause:
Typical Problem
Zero OUI readout
Erratic OUI readout
Incorrect OUI readout
Probable Cause
Open circuit/cable disconnected
Loss of power to transmitter
Malfunctioning transmitter
Loose wire/terminal/connector
Any
Troubleshooting Procedure
PMS #1, 2
PMS #1
PMS #3, 4
PMS #1,2
PMS #1, 2, 3, 4
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
67
CMC TECHNICAL REFERENCE MANUAL
Checking for Power to the Pressure Transmitter
PMS #1
1. Ensure control power is off. Disconnect the wires at the suspect PT and connect a
voltmeter to these wires.
2. With control power on, there should be approximately 24 VDC present at the terminals.
3. If approximately 24 VDC is not present, see the section titled “Control Power System”.
BCM
J2-Floating Analog Inputs, (4-20mA) Channels 1-2
J1-Grounded Analog Inputs,
(4-20mA) Channels 3-23
Pin 25
Pin 1
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
SPAN
VDC
mA
®
VAC
Ω
mA COM V Ω
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
INGERSOLL RAND
68
CMC TECHNICAL REFERENCE MANUAL
Checking proper operation of the BCM and wiring
PMS #2
1. Ensure control power is off. Disconnect the wires at the suspect PT and connect a 4-20
mA source to the lifted wires (Observe correct polarity).
2. Restore control power and then vary the simulator output.
3. At 12 mA (50%) the OUI should read 1/2 the PT range. The readout should change as
the simulator output is varied.
4. If the reading on the OUI is incorrect or does not change, turn control power off and
reconnect the transmitter, remove the wires for this transmitter from J1 and move the 420 mA simulator to the respective terminals at connector J1, (see electrical schematic for
connection points).
5. Turn control power on and observe the OUI readout while varying the 4-20 mA. If the
reading is correct there is an open or short in the wire or terminals connecting the CMC
to the PT. If the reading is not correct the BCM may be faulty.
BCM
J2-Floating Analog Inputs, (4-20mA) Channels 1-2
J1-Grounded Analog Inputs,
(4-20mA) Channels 3-23
Pin 25
Pin 1
4-20 mA SURCE OR
2 WIRE SIMULATOR
LOOP
ON
DIAL
100%
BATTERY
CHECK
OFF
2 WIRE
mA OUT
00.0% - 100%
00.0%
XXXXXX
MODEL CL-XXX
555
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
69
CMC TECHNICAL REFERENCE MANUAL
Quick check of the PT
PMS #3
1. Connect an ohmmeter to the disconnected wires coming from the PT.
2. If there is no continuity either the wiring or the PT is faulty.
M
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
XXXXX
VDC
mA
VAC
Ω
mA COM V Ω
SPAN
®
INGERSOLL RAND
Functional PT test
PMS #4
1. Remove control power.
2. Remove the PT and connect a regulated air supply to the pressure connection. Power
up the CMC and vary the regulated air supply. The OUI should read the pressure being
applied.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
70
CMC TECHNICAL REFERENCE MANUAL
Digital Input System (DIS)
Description:
The digital input devices associated with the CMC are on/off devices that turn on or off the
associated CMC digital input.
Typical digital device name and type:
1.
Low seal air pressure (Pressure)
2.
Low cooling water flow (Flapper)
3.
Low oil level (Float)
4.
High condensate level (Float)
5.
Dirty inlet filter (Differential pressure)
6.
Dirty oil filter (Differential pressure)
7.
High motor temperature (Thermistor)
Troubleshooting:
The following table identifies typical problems, probable causes, and appropriate
procedures for verifying the probable cause:
Typical Problem
False alarm or trip
Probable Cause
Faulty device
Faulty wiring
Troubleshooting Procedure
DIS #1
DIS #1
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
71
CMC TECHNICAL REFERENCE MANUAL
Checking proper operation of the digital devices
DIS #1
1. Verify approximately 24 VDC is present as described in the section titled
“Troubleshooting the Power System”.
2. If approximately 24 VDC is present, install a multimeter with VDC selected between J4
or J5 pin1 and the input pin (the input pin can be determined from the electrical
schematic, or wire number).
3. Ensure the digital device is not in the trip condition, the meter should read 0 VDC.
4. Actuate the switch, the meter should read approximately 24 VDC.
J6-RS232 Serial
Data Link (Display),
Female DB9
BCM
J5-Digital (Discrete)
Inputs (24 VDC),
Channels 9-16
Pin 1
XXXXX
XXXXX
XXXXX
XXXXX
J4-Digital (Discrete)
Inputs (24 VDC),
Channels 1-8
XXXXX
XXXXX
VDC
mA
VAC
Ω
mA COM V Ω
Pin 1
Seal Air Switch
J3-Analog Outputs
(4-20mA)
Channels 1-4
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
72
CMC TECHNICAL REFERENCE MANUAL
Control Power System (CPS)
Description:
The control power system provides 24 VDC to the CMC system for processing logic,
displaying data, and monitoring instrumentation. The 24 VDC power supply feeds the Base
Control Module (BCM) at connector J10. Over current protection and power distribution are
performed as shown below:
J2
+24 VDC pins 11 thru 14
J1
AC2 pin 3
Power Supply
F1
AC1 pin 1
Return pins 7 thru 10
BCM shown
cover removed
Fuse 5A/250VAC, normal blo.
J12-Digital Output Power 120 VAC (Pin 1)
To OUI J2 pin 2
To OUI J2 pin 1
OUI Power
To Ground Bar
J10-Power Input (24 VDC)
F100
F101
F102
F103
J9-Current Transformer
(0-5 amp)
CPU Power
All BCM Fuses are 5x20mm,
GMA 1.5 amp, Fast Blow
BCM
Digital Input Power
J4 & J5 - Digital Input Power 24 VDC (pin 1)
Analog Input/Output Power
LEGEND:
Trace
Wire
J3- Analog Output Power 24 VDC (pins 2 & 8)
J1- Analog Input Power 24 VDC (pin 26)
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
73
CMC TECHNICAL REFERENCE MANUAL
Power Supply:
•
Input power: 85-132 VAC, or 180-264 VAC (auto-selecting input), 2.5A RMS max, 47-63
Hz.
•
Output power: 24 VDC, 4.3 A maximum at 50 °C.
Troubleshooting:
The following table identifies typical problems, probable causes, and appropriate
procedures for verifying the probable cause:
Typical Problem
Probable Cause
All analog inputs are zero or negative on System Page
No AC power
No DC power
No analog input
power
No CPU power
OUI displays: “INGERSOLL-RAND Centrifugal
Compressor Division”
OUI is black
Event Log indicates all digital alarms and trips active
All digital outputs not working
All analog outputs not working
BCM problems
No AC power
No DC power
No OUI power
No AC power
No DC power
No digital input
power
No AC power
No DC power
No digital output
power
No AC power
No DC power
No analog output
power
Troubleshooting
Procedure
CPS #1
CPS #2
CPS #5
CPS #8
CMCS #3
CPS #1
CPS #2
CPS #7
CPS #1
CPS #2
CPS #3
CPS #1
CPS #2
CPS #4
CPS #1
CPS #2
CPS #6
No AC power
CPS #1
1. Ensure control power is off.
2. Install a multimeter set for VAC between pins 1 and 3 at connector J1 on the power
supply.
3. Restore control power, the meter should read 120 VAC or 220 VAC depending upon
the rated supply power. The rated supply power can be verified from the electrical
schematic.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
No DC power
CPS #2
1. Ensure control power is off.
2. Install a multimeter set for VDC between pins 11-14 and 7-10 at connector J2 on the
power supply.
3. Restore control power, the meter should read approximately 24 VDC. If approximately
24 VDC is not present, check F1 on the power supply, if fuse is good, the power supply
may be faulty.
4. Ensure control power is off.
5. Install a multimeter set for VDC between pins 1 and 2 at connector J10 on the BCM.
6. Restore control power, the meter should read approximately 24 VDC. If approximately
24 VDC is not present, check the wiring between the power supply and the BCM.
No digital input power
CPS #3
1. Ensure control power is off.
2. Install a multimeter set for VDC between pin 1 at connector J4 on the BCM and the
ground bar.
3. Restore control power, the meter should read approximately 24 VDC. If approximately
24 VDC is not present, check F103 on the BCM, if F103 is good, check for DC power.
No digital output power
CPS #4
1. Ensure control power is off.
2. Install a multimeter set for VAC between pin 1 at connector J12 on the BCM and the
ground bar.
3. Restore control power, the meter should read 120 VAC.
No analog input power
CPS #5
1. Ensure control power is off.
2. Install a multimeter set for VDC between pin 26 at connector J1 on the BCM and the
ground bar.
3. Restore control power, the meter should read approximately 24 VDC. If approximately
24 VDC is not present, check F102 on the BCM, if F102 is good, check for DC power.
No analog output power
CPS #6
1. Ensure control power is off.
2. Install a multimeter set for VDC between pin 2 at connector J3 on the BCM and the
ground bar.
3. Restore control power, the meter should read approximately 24 VDC. If approximately
24 VDC is not present, check F102 on the BCM, if F102 is good, check for DC power.
No OUI power
CPS #7
1. Ensure control power is off.
2. Install a multimeter set for VDC between pins 1 and 2 at connector J2 on the OUI.
3. Restore control power, the meter should read approximately 24 VCD. If approximately
24VDC is present, check F2 on the OUI. If F2 is good, go to next step.
4. Restore control power, the meter should read approximately 24 VDC. If approximately
24 VDC is not present, check F101 on the BCM, if F101 is good, check for DC power.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
No CPU power
CPS #8
1. Ensure control power is off.
2. Verify approximately 24 VDC is present at J10.
3. Check F100, if F100 is blown the BCM must be replaced, not the fuse.
4. If F100 is not blown, and the BCM is not functioning, the BCM must be replaced.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
75
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CMC TECHNICAL REFERENCE MANUAL
Controller Problems
Description:
The CMC System is generally comprised of a Base Control Module (BCM), Operator User
Interface (OUI), and Power Supply (PS). There are few user serviceable components within
the system; however, a brief understanding of the system will help in overall
troubleshooting. All components require 24 VDC and rely on hardware and software to
perform correctly, if the problem cannot be isolated to a power problem it is most likely a
hardware or software problem, which will require Ingersoll-Rand support to correct.
Component Specification:
•
VDC power required
•
Software required
Troubleshooting:
The following table identifies typical problems, probable causes, and appropriate
procedures for verifying the probable cause:
Typical Problem
Probable Cause
BCM fault suspected
OUI is dim
No power
Wrong contrast selected
Backlight failing
No power
Cable disconnected
OUI is black
OUI displays “INGERSOLL-RAND
Centrifugal Compressor Division”
OUI displays “Status XXH”
Where XX is a specific number
Many
MODBUS communications problem No power
Many
Troubleshooting
Procedure
CMCS #4
CMCS #1
CMCS #1
CMCS #2
CMCS #3
Refer to Status Codes
under System Information
Section.
CMCS #5
Refer to the UCM
Section.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
77
CMC TECHNICAL REFERENCE MANUAL
BCM Problems
BCM is not controlling
CMCS #4
1. Check the CPU power as described in the section titled “Control Power System”.
OUI Problems
OUI is dim
CMCS #1
1. Depress the contrast key to step to the desired brightness.
2. Replace the OUI backlight as described in the section titled “Backlight Replacement
Procedure”. If the backlight does not fix the problem the OUI may be faulty.
OUI is black
CMCS #2
1. Check for OUI power as described in the section titled “Control Power System”. If
approximately 24 VDC is present, check F2. If F2 is O.K. the OUI may be faulty.
OUI displays “INGERSOLL-RAND Centrifugal Compressor Division”
1. Check the cabling between OUI J1 and BCM J6.
2. The BCM may require programming.
3. Check the BCM CPU power.
4. The BCM may be faulty.
CMCS #3
UCM Problems
All UCM LED’s are not lit
1. Check for approximately 24 VDC at pins 1 and 2 at J3 on the UCM.
2. If power is present at J3 the UCM may be faulty.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMCS #5
78
CMC TECHNICAL REFERENCE MANUAL
Options
This section details the various standard options that are available for the CMC. Some of
the options listed are provided standard on some models, and will be indicated as such.
Enclosures
The CMC has three panel enclosures available; NEMA 12 (IP 64), which is standard, and
optional NEMA 4 (IP 65) and NEMA 4X (IP 65). The panel is machine mounted. All
electrical devices are mounted and wired where practical.
NEMA 12 (IP 64)
NEMA 12 is the standard enclosure for all compressors with CMC panels. NEMA defines
this rating as "... intended for indoor use primarily to provide a degree of protection against
dust, falling dirt, and dripping non-corrosive liquids. They shall meet drip, dust, and rustresistance design tests. They are not intended to provide protection against conditions such
as internal condensation.” Typically this type of enclosure is applied for most indoor
applications.
Cooling Fan
The cooling fan is supplied on all standard CMC enclosures, where a wye-delta motor
starter is present, the Control Electrical Package is included, or the ambient temperature
exceeds 40°C keeps the internal temperature below the maximum operating temperature
allowed. This action effectively extends the operating life of the control components. A filter
and gasket are added to attain a NEMA 12 rating.
NEMA 4 (IP 65)
This optional enclosure type is applied for most outdoor applications. Indoor applications
that are subject to hose washing would also apply to this standard. NEMA defines this
rating as "... intended for indoor and outdoor use primarily to provide a degree of protection
against windblown dust and rain, splashing water, and hose directed water; and to be
undamaged by the formation of ice on the enclosure. They shall meet hose down, external
icing, and rust-resistance design tests. They are not intended to provide protection against
conditions such as internal condensation or internal icing."
The standard panel enclosure is replaced with a new box that meets the above
requirements. The User Terminal vinyl overlay and sealing bezel is door mounted and
allows direct interface with the environment. NEMA 4 rated lights, switches and buttons are
mounted directly through the panel door. A panel space heater and Vortex Tube Cooler are
added to accommodate changes in ambient temperatures.
NEMA 4X (IP 65)
Also an optional enclosure type that should be applied in the same type of NEMA 4
applications within corrosive environments. The basic difference between NEMA 4 and
NEMA 4X is that the panel enclosure is constructed with stainless steel.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
Space Heater
Required for NEMA 4 and NEMA 4X panels to protect the panel from internal condensation.
This option should also be used with NEMA 12 for unheated building applications.
Vortex Tube Cooler
This panel cooler is required on NEMA 4 and NEMA 4X enclosures to maintain the
operating temperature below the maximum. An adjustable thermostat is provided to open
and close a solenoid operated valve from the instrument air header in the panel. The cooler
works by converting filtered compressed air into a hot air stream and cold air stream. The
hot air stream is vented external to the enclosure and the cold air stream is directed into the
enclosure.
Type Z Purge
The CMC requires a Type Z Purge when the customer environment is Division 2. A Type Z
Purge reduces the classification within an enclosure from Division 2 too non-hazardous.
When provided, a NEMA 4 or NEMA 4X enclosure is required. Hand valve selectable quick
and slow purges, with flow meters are provided to regulate the amount of gas entering the
panel. A differential pressure switch is wired to a light on the front of the panel to indicate if
there is a loss of purge gas. A relief valve is installed to prevent over-pressurization and a
warning label, text below, is affixed to the front of the panel.
WARNING
Enclosure shall not be opened unless the area is known to be non-hazardous
or unless all devices within the enclosure have been de-energized. Power shall not
be restored after the enclosure has been opened until combustible dusts have been
removed and the enclosure re-pressurized.
Fused Control Power Disconnect
As a safety precaution, this option removes power from the panel before the door is
opened. By turning the rotary door handle, the panel power is terminated. If the disconnect
is to include fuse size provisions for the main motor starter, additional information is
required. The disconnect would have to be mounted external to the panel enclosure. The
short circuit capacity, maximum ground fault, motor full load amps, motor locked rotor amps
and motor voltage must be known to size the disconnect properly. Pricing varies depending
upon the size, amp rating of the fuse, which is required for protection.
NOTE
This option does not make fuse size provisions for the main motor starter.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
Control Electrical Package
The Control Electrical Package consists of a Control Transformer, Prelube Pump Starter,
Oil Heater Contactor(s) and Transient Voltage Surge Suppressor. This option allows the
customer to bring a single source of electrical power to the compressor to run all of the
compressor package accessories; thereby, making compressor installation easier.
Stage Data Package
For monitoring of interstage pressure and temperatures, the Stage Data Package can be
added. As standard, the CMC comes with temperature readout, alarm and trip for the next
to last compression stage and compressor discharge pressure indication. When selected,
each stage gets temperature and pressure measurements on the downstream side of each
stage's cooler. For compressors without built-in aftercoolers, the last stage diffuser
temperature is measured. Each temperature has readout, alarm and trip capability while the
pressures are readout only.
Alarm Horn
The optional alarm horn sounds any time there is an alarm or trip situation. The horn output
will pulse for an alarm and remain constant for a trip. This allows the operator to distinguish
between each fault type without viewing the OUI. The horn silence push-button is located
on the CMC faceplate to silence any audible devices connected to the CMC board.
Running Unloaded Shutdown Timer
The intent of this option is to save energy by shutting the compressor off during extended
periods of unloaded operation. When the running unloaded shutdown timer is enabled with
the RUNNING UNLOADED SHUTDOWN TIMER DISABLED/ENABLED selector switch,
the auto-dual control mode should be selected, this provides for automatic unloading of the
machine during periods of low demand.
Water Solenoid Post Run Timer
This optional panel function is used to shut off water flow to the air and oil coolers after the
compressor is stopped. It is accomplished by sending a signal to close the solenoid
operated water valve(s).
Panel Mounted Wye-Delta Starter
Main motor starter enclosed in the CMC panel. This feature allows the customer to wire the
compressor from a single source; thereby, eliminating most electrical wiring and starter
installation expense. These starters are available for compressors with motors up to 350
HP and 575 Volts.
N.O. Contact for Remote Indication of Common Alarm and
Trip
A normally open contact for individual remote indication closes whenever an alarm or trip
occurs. This allows a customer to have remote indication of compressor alarm, trip or both.
Power Regulating Constant Voltage Transformer
If the electrical power supplied to the CMC varies more than ten percent, this transformer
must be added to bring the voltage within the specification requirements.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
Automatic Starting
NOTE
Most electric motors are only rated for two cold starts or one hot start per hour. It is
the operator’s responsibility not to exceed the electric motor’s limitation. The control
system allows the compressor to be started when the compressor is ready, not the
motor.
Remote start and stop through hard wiring to the compressor control panel, communicating
through the MODBUS port via RS422/485, Auto-Hot Start and Auto-Cold Start are the four
options for automatically starting and stopping with the CMC. With each of these options a
REMOTE COMMUNICATIONS DISABLED/ENABLED or REMOTE FUNCTIONS
DISABLED/ENABLED, selector switch is provided on the device plate with a REMOTE
ENABLED light. Since each option performs basically the same function, only one should
be purchased for a single CMC. The specific method selected depends upon the
application.
Remote Start and Remote Stop – Hardwired
When this option is purchased, two digital inputs are configured on the CMC Base Control
Module, one for remote start and one for remote stop.
Remote Start Digital Input
This input is driven by a momentary contact closure of at least 120 milliseconds. For the
start to proceed, the panel power must be on, the compressor must be in the Ready state
(all utilities must be running and permissive functions satisfied) and the REMOTE
FUNCTIONS DISABLED/ENABLED selector switch is in ENABLED mode prior to
energizing the input.
Remote Stop Digital Input
This input is driven by a maintained contact closure. The remote stop input is always active;
that is, the remote stop can be initiated regardless of the REMOTE FUNCTIONS
DISABLED/ENABLED selector switch position.
Communications
Remote starting and stopping can be accomplished through the MODBUS communication
port in various ways. See the section on Communications that follows for these options.
Again, panel power must be on, all utilities must be running and permissive functions
satisfied in order for the start-up to proceed.
Auto-Hot Start
Normally purchased in multiple compressor applications where backup air is required, this
automatic starting option allows the compressor to be started when the system air pressure
is below a user selected set point pressure.
Panel power must be on, all utilities must be running, the AUTO HOT START
DISABLED/ENABLED selector switch must be in the ENABLED position and all permissive
functions satisfied in order for the start-up to proceed. Solenoid water valve(s) are provided
for the intercooler(s) to reduce water consumption when the compressor is not running. A
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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CMC TECHNICAL REFERENCE MANUAL
post run timer is also included in the Auto Hot Start logic to de-energize the water solenoid
valves twenty minutes after a compressor stop or trip to allow the oil to cool.
Auto-Cold Start
This option is very similar to Auto-Hot Start with the exception that the compressor starts
with no initial panel power. An additional timer is added to simulate the start button being
pressed and another timer is added to bypass the low oil temperature function on start-up.
One additional solenoid valve is included for instrument air supply. The CONTROL POWER
OFF/ON selector switch label is modified to CONTROL POWER LOCAL/OFF/COLD
START. When in the COLD START position, the compressor is OFF and can be started
through the Auto-Cold Start function. As a safety precaution, an optional strobe light can be
provided to indicate that an automatic start is about to begin.
Remote 4-20 mA Pressure Setpoint
When the REMOTE FUNCTIONS DISABLED/ENABLED selector switch is in the ENABLED
position, the CMC will monitor the specified analog input for pressure setpoint. If this analog
input’s value minus the Pressure Setpoint (from the display) is greater than or equal to the
display’s Pressure Setpoint step value (default 0.1 psi), a remote setpoint change will be
requested. This request will be initiated, as long as there are no analog input error faults for
this channel, and the change made will rounded to the nearest step value (0.1) size. This
methodology prevents the control system from chasing an ever-changing analog input
value.
Ambient Control plus Parallel Valve Control Logic
Ambient Control
This feature uses Polytropic Head (or just Head) as the MinLoad control variable. By using
Head, a more conservative MinLoad setting can be established which contributes to energy
efficiency. For additional information on Polytropic Head, see section under SURGE
CONTROL / Control Methodology.
Polytropic Head may be selected as the MinLoad control variable for Pressure Control (the
standard process control for the CMC), or optional Flow Control. Polytropic Head may also
be selected as the MinLoad control variable for Steam and Gas Turbine Driven and Diesel
Driven Compressors.
Parallel Valve Control Logic
This feature includes a number changes to control logic to improve valve transitions.
•
One feature is improved State Transitions. The overall effect will be better
response to system dynamics requiring state changes.
An example of this is inlet valve throttling. When the machine is rapidly throttling
from Loaded State to the MinLoad state, the inlet valve will transition to MinLoad
before actually reaching the Minload setpoint. The valve transition offset is a
function of the PID settings for the MinLoad and Loaded loops and the rate at which
the process control variable is rising. By making this transition early, improved
control response is achieved. In this case, undershoot of MinLoad would be
decreased and overshoot of the process variable would be decreased relative to
previous CMC releases.
•
For installations with big, quick swings in load that get the check valve opened and
closed frequently a new Discharge Pressure Regulation feature may be selected
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to provide better pressure control. Previously these large changes required the
MinLoad to be set more conservatively. Otherwise if the controller could not react
fast enough the system would decay while closing the bypass valve.
This new control loop will regulate compressor discharge pressure when the
discharge check valve is closed. Adding this loop also eliminates windup of the
bypass valve and allow for quicker reentry into the system. This feature requires
configuration by an Ingersoll-Rand service technician.
•
Typically, overshoot can occur when the system being regulated has a significant
change in dynamic response and the PID parameters are not changed accordingly.
For compressor control, this happens when the controller used the same bypass
valve PID values for control regardless of the check valve state. One way to handle
this is with the above Discharge Pressure Regulation feature previously described.
If the installation does not warrant setting up Discharge Pressure Regulation, the
Loading Ramp rate feature is used to accommodate this check valve complication.
The Loading Ramp feature minimizes overshoot upon a load command.
•
An additional feature called Unloading Interrupt is also a part of the CMC. The
unloading state can now be interrupted by a load command and reload the machine
without completely unloading it.
•
Deadband on Control Variables is another feature of Parallel Valve Control Logic.
This feature prevents valve oscillations when the Process Variable is steady state.
Steady state valve oscillation is primarily a result of the control valve’s inability to
position as finely as required by the PID control loop. A typical scenario would be
when the CMC commands the valve to open 0.05% and the valve opens 0.1%. The
valve now needs to close 0.05% but will likely close 0.1% causing the cycle to start
over. This feature requires configuration by an Ingersoll-Rand service technician.
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Mass Flow Control
Constant flow control is a performance control method for Centac air compressors.
Uncontrolled, the compressor's
discharge flow would rise and fall
along the natural performance
Surge Line
curve as system flow demand
changed. Constant Flow control
Maximum
satisfies the constant flow
Throttle Points
(MinLoad)
Discharge
requirement.
Pressure
This performance map shows
Constant Flow control. Constant
Flow control maintains the
compressor discharge flow into the
system at the Flow Setpoint as
entered into the CMC by the user.
Once loaded, the compressor will
operate along the constant flow
line until the user presses the
Unload or Stop button.
Natural
Pressure
Curve
Design
Point
Constant
Flow Line
Unloaded
Natural
Power
Curve
Surge Line
Power at
Control is accomplished by
Coupling
modulating the inlet valve within
the compressor's operating range.
When the compressor’s demand is
Unloaded
less than the minimum throttled
capacity, constant flow is
Capacity
maintained by modulating the
bypass valve and venting some or
all of the air to atmosphere. This
Figure 20: Constant Flow Control
valve is opened just prior to reaching
the surge line. Whenever the bypass valve is open, the inlet valve maintains its position at
the minimum throttled capacity setting. Constant Flow provides a constant discharge flow
with variable pressure up to the natural surge point.
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Measuring the Flow
In order to maintain constant flow, the system discharge airflow must be measured. A flow
transducer is mounted in the customer’s piping upstream of the check valve.
CMC
4-20 mA
Bypass
Valve
FT
4-20 mA
Base
Control
Module
CT
Starter
Motor
4-20 mA
Check
Valve
FE
Compressor
PT
x
Inlet
Valve
4-20 mA
Figure 21: Measuring Flow
This transducer sends a 4-20 mA signal to the CMC board. The CMC compares the
measured flow to the flow setpoint entered into the CMC by the user through the Operator
User Interface (OUI). Depending upon the difference between these two values the CMC
will send a 4-20 mA signal to open or close the inlet and/or bypass valve to maintain the
specified compressor flow setpoint.
Steam and Gas Turbine Driven Compressors
The following describes the differences between the motor and turbine driven compressor
logic.
Performance Control
Motor Current, MinLoad and MaxLoad
Steam and gas turbines do not have motor current, MinLoad and MaxLoad operate
differently form the normal motor driven compressor. MinLoad uses an inlet valve position,
instead of amps, to determine when to transition from Inlet Valve Pressure control to
Bypass Valve Pressure control. When in MinLoad, the controller uses this valve position as
the setpoint for the Inlet Valve MinLoad PID loop. Since the controlled variable and the
setpoint variable are identical, the goal of tuning this loop is to get a steady output. The
default parameters will satisfy most all applications. The procedure for determining the
MinLoad point is the same for both motor and turbine driven units, except inlet valve
position is recorded instead of motor amps.
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CAUTION
Improperly tuning MinLoad PID values will result in unpredictable compressor
operation. If this situation arises, reset the PID values to the default values.
MaxLoad situations are detected on turbine driven compressors by low speed. The
MaxLoad setpoint is a speed below the rated speed and above the low speed alarm. This
speed is determined by adding an offset to the low speed alarm. This offset is the speed
that the governor can accurately control.
Surge Control
All surge related issues are identical to motor driven units with the exception of the
detection methodology.
How Surge is Detected
The CMC senses surge when the rate of change in last stage discharge pressure is greater
than the surge sensitivity setpoint value.
The difference between this and motor
Compressor Operating States
driven units is that the motor driven units
Turbine Driven Packages
uses rate of change in motor amps also.
Compressor Operating Methodology
Comparing the chart to the right for
Turbine driven compressor and Motor
driven compressor, the only state
differences are the addition of the first
three states under Rotating. These are
Accelerate-1, Accelerate-2 and Slow
Rolling.
Accelerate-1
+
Compressor
+
Stopped
Waiting
Not Ready
Ready
+
Rotating
Accelerate-1
Accelerate-2
Slow Rolling
This state is provided to give the operator
Starting
five minutes from the time the Start button
Unloaded
is pressed to get enough steam to the
turbine to get the speed above the Zero
A-D Unloaded
Offset Speed. This speed is defaulted to
Surge Unload
15 rpm. If this speed is not achieved in
Loading
this time period, the event message
MinLoad
“Accelerate-1 Fail” will appear and the
controller will trip the compressor. As
Loaded
always, the compressor must be “Ready”
Full Load
before the start button is pressed. The
MaxLoad
reason for the five-minute limitation is to
Unloading
prevent the compressor from being ready
for an indefinite period of time. This
Coasting
prevents the operator from forgetting that
the compressor is ready to accelerate. “Accelerate-1” could also be explained as
“accelerating to zero speed offset” or “waiting for compressor rotation”.
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Accelerate-2
After the transition to Accelerate-1 is complete, this state is initiated when rotation is
detected and the turbine has not reached the low trip speed. This state may be bypassed if
the turbine accelerates very quickly.
Once in this state, a sixty (60) second timer is initiated. If the speed does not get to the
minimum slow roll speed within this time period, the event message “Accelerate-2 Fail” will
appear and the controller will trip the package. This state is limited sixty (60) seconds to
prevent bearing damage from rolling the compressor at too low a speed. The bearing
design requires a minimum speed to form the oil film thickness required for proper bearing
operation. “Accelerate-2” could also be explained as “accelerating to minimum slow roll
speed”.
Slow Rolling
After the transition to Accelerate-2 is complete, this state is entered after the previous sixtysecond timer has elapsed and the speed is less than the low trip speed. The compressor
can operate in this “Slow Rolling” state indefinitely. While in this state, if the speed drops
below the minimum slow roll speed, the event message “Slow Roll Fail” will appear and the
controller will trip the compressor. If at any time during “Slow Rolling” the speed exceeds
the maximum slow roll speed, the compressor will transition to “Starting”. The Starting state
for turbine driven compressors is the same as for motor driven compressors.
Quick Start Turbines
Quick Start turbines may skip “Accelerate-2” and “Slow Rolling” or just “Slow Rolling”
because of the acceleration characteristics. The acceleration sequence depends upon the
acceleration characteristics for a given turbine.
Operator User Interface (OUI)
Status Bar
Motor driven compressors have an optional Compressor Status Field for Start Disabled.
This field is standard for turbine driven compressors and it means that the turbine trip and
throttle valve limit switch has not been made.
System Folder
Replacing “Motor Current “with” Compressor Speed” on Page 1 is the only modification to
this folder.
Info Folder
The events “Starter Failure” and ”Loss of Motor Current have been deleted from the
possible event list. The following events have been added.
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Possible Events List
Event Name
Description
Accelerate-1 Fail
The zero offset speed has not been achieved before the end of the five-minute timer.
Accelerate-2 Fail
The minimum slow roll speed has not been achieved before the end of the one-minute timer.
Driver Trip
The trip and throttle valve limit switch has been latched, then unlatched.
Governor Common Trip
The governor has tripped.
High Speed Alarm
The indicated speed is greater than or equal to the High Speed Alarm setting.
High Speed Trip
The indicated speed is greater than or equal to the High Speed Trip setting.
Illegal Rotation
Rotation has been detected when in “Stopped”.
Low Speed Alarm
The indicated speed is less than or equal to the Low Speed Alarm setting.
Low Speed Trip
The indicated speed is less than or equal to the Low Speed Trip setting.
Slow Rolling Fail
The minimum slow roll speed was not maintained during “Slow Roll”.
Starting Fail
The low trip speed was not achieved before the end of the Starting Timer.
TTV Switch Fault
The trip and throttle valve (TTV) limit switch is made when the (TTV) solenoid is de-energized.
Settings Folder
For Page 2, Anti-Surge and Driver Over-Load Protection …
1. “MaxLoad (HLL), amps” is replaced with “MaxLoad (HLL), rpm”.
2. “User Setpoint (TL), amps” is replaced with “User Setpoint (TL), IV Pos %”.
3. “Control Setpoint, amps” is replaced with “Control Setpoint, IV Pos %”.
4. “Surge Index Increment, amps” is replaced with “Surge Index Increment, IV Pos %”.
For Page 5, Miscellaneous
1. “CT Ratio” is removed.
2. “Motor Failure Trip Enable” checkbox is removed.
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General Sequence of Operation
Compressor Operating States
Coasting
Unloaded
Unloading
MaxLoad
Full Load
Loaded
MinLoad
Loading
Unloaded
Starting
Ready
Not Ready
Waiting
for Turbine and Diesel Driven Packages
Any
Stops or
Trips
Mechanical Trip (110%)
Overspeed Trip (108%)
Overspeed Alarm (105%)
Rated "Full Load" (100%)
MaxLoad (HLL)
Low Alarm (95%)
Low Trip (93%)
SPEED
Maximum Slow Roll (50%)
Minimum Slow Roll (25%)
No
Stops or
Trips and
Latch
Start
Zero Speed Offset (15 rpm)
(0%)
Power
On
Stopped
Rotating
Starting Methodology
1. The panel power is turned on. The compressor is WAITING.
2. The CMC Panel mounted switch for DRIVER SPEED RATED/IDLE (when supplied for
an electronic governor) should be put into the IDLE position. This switch is wired to a
discrete input (Driver Speed Rated/Idle) in the CMC and is sent on the discrete output
(Driver Speed Rated/Idle) to the governor.
3. When the two-minute waiting timer has expired, the compressor is NOT READY.
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4. Reset the governor to clear any trip signals. This may be accomplished with the digital
output (Reset – Momentary). If an electronic governor exists, a discrete output signal
(Common Trip) is sent from the governor to a discrete input signal on the CMC when
the governor needs to trip the compressor. If no electronic governor exists, a jumper
must be installed on the CMC board.
Adaptive StartingTM Techniques
Low Trip (93%)
Starting
Starting
Starting
SPEED
Slow Rolling
Maximum Slow Roll (50%)
Accelerate-2
Accelerate-2
Minimum Slow Roll (25%)
Accelerate-1
Accelerate-1
Accelerate-1
Zero Speed Offset (15 rpm)
(0%)
5. When NO Trips exist (compressor and turbine), the CMC energizes the turbine’s trip
and throttle valve (TTV) solenoid. This is accomplished through a discrete output (Driver
Permissive) from the CMC to the TTV solenoid.
6. At this point, the compressor is NOT READY, Driver Disabled.
7. When the TTV solenoid is energized, the turbine trip valve can be latched.
8. When the turbine trip valve is manually latched, the turbine trip valve’s limit switch will
be energized. This signal is sent to a discrete input (Trip and Throttle Valve Limit
Switch) on the CMC.
9. When the limit switch is energized and no stop command is pending, the compressor
will be READY. This state may be maintained indefinitely.
10. The Start Key is pressed on the compressor. The digital output (CR1) is energized to
actuate the solenoid operated steam valve and the digital output (Start – Momentary) is
energized. A timer (five minute maximum) is started. At this point, enough steam should
be applied to the turbine to get the speed above the zero speed offset. This period is
ACCELERATE-1.
11. Once the zero speed offset has been established, a one minute timer is provided to
prevent compressor pinion damage from rotating the pinions at too low a speed for an
excessive time. The compressor bearings are designed to have a minimum oil film
pressure created by a minimum rotating pinion speed. Therefore, we must not stay at
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too slow a speed for an extended period. This is ACCELERATE-2. The turbine must
reach the Minimum Slow Roll Speed (approximately 25% of Full Speed) to continue.
12. Once the turbine gets past the Minimum Slow Roll Speed and is less than the Maximum
Slow Roll Speed (approximately 50% of Full Speed), the turbine is in the slow rolling
zone and the compressor is SLOW ROLLING. The User may leave the compressor in
this mode indefinitely. The CMC monitors the compressor speed (through the speed
analog input) in this mode. The Idle/Rated Driver Speed switch is turned to the Rated
position.
13. When the turbine speed exceeds Maximum Slow Roll Speed, the Starting Timer begins
(60 seconds maximum) and is STARTING. This is the same time for motor driven
compressors; therefore, the User must put enough steam to the turbine to get the speed
above the low trip speed before the timer expires. At this point, the compressor has
started and runs as described elsewhere.
Instrumentation for Turbine Driven Compressors
Centac Microcontroller
Discrete Outputs (DO)
CR1
TTV Solenoid Energize (Driver Permissive)
TTV Limit Switch
Start - Momentary
Stop - Momentary
Reset - Momentary
Driver Speed Rated/Idle
DI
Discrete Inputs (DI)
DO
Common Trip
Electronic
Governor
AO
Driver Speed
Rated/Idle
Switch
on Panel
Door
Analog Input (AI)
Speed
AI
Speed
Turbine
TTV Solenoid
Manual Latch
Limit Switch
Steam
Throttle Valve
Trip Valve
Solenoid Steam Valve
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Diesel Driven Compressors
Diesel driven compressors have similar characteristics as the turbine driven compressors.
The differences are…
1. “Idle/Rated Driver Speed” discrete input and discrete output are eliminated.
2. “Start – Momentary”, “Stop – Momentary” and “Reset – Momentary” discrete outputs
are eliminated.
3. “Driver Permissive” discrete output is wired to the “Trip and Throttle Valve Limit
Switch” discrete input.
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Communication
Customers may want to communicate to the CMC control systems for remote compressor
control and monitoring. This communication capability provides for flexibility in the
customer's compressed air operation through remote start and stop, data gathering for
preventative maintenance, and incorporation into plant-wide control system.
The major avenue for communicating with the CMC is via MODBUS protocol over an
RS422/485 hardware link. This requires hardware for the control panel, and a
communications device with the appropriate driver software to perform the desired panel
functions. The RS422/485 interface can communicate with any serial device that has an
RS422 or RS485 port. The customer or his representative must write system software to
suit his individual needs for remote control and monitoring. Since the customer writes this
interface, the system can be as flexible as the customer desires.
Human Machine Interface (HMI) Systems
Air System Controller (ASC) and Air System Manager (ASM) are software packages
available for compressors with CMC panels.
ASC and ASM are graphical integration software specifically developed for air compressor
systems. Both provide energy management through load sharing and reduction of air
bypass by using a minimum amount of energy to meet the system demand. The primary
goal of both systems is to maintain stable system pressure, to integrate, monitor and control
the compressed air system.
ASM is the integration of compressor control software in an off-the-shelf Supervisor Control
and Data Acquisition (SCADA) package that is available from various manufacturers. The
ASM provides more custom features than does ASC.
Both ASC and ASM provide a window into the compressor room by making the raw data
from compressors and other equipment available to plant operators and managers in
formats that are easy to understand.
Implementing the CMC in any HMI system may require additional hardware and/or software
upgrade.
Direct CMC Communications with RS422/485
For the descriptions that follow, a serial device can be a Personal Computer (PC),
Programmable Logic Controller (PLC), Distributed Control System (DCS) or any other
device that can transmit, receive and interpret an RS422/485 formatted signal over a
hardware link. In the descriptions that follow, the PC and PLC serial devices are not specific
to manufacturers or operating systems.
There are many ways of interfacing to CMC control systems through an RS422/485 port.
Most of the following methodologies are currently available; but please be aware, other
possible configurations can exist.
All RS422/485 interfaces require custom interface software and custom application
software. The interface software allows a specific serial device and operating system to
transmit, receive and interpret data from a CMC control system. The application software
tells the CMC control system what to do; for example, start compressor when ready, stop
compressor after midnight and retrieve the current data and save to a disk file.
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Currently there are hundreds of different serial devices using different operating systems
and languages in the industrial equipment world. Therefore, the practicality of having an
interface for many systems is limited. Custom interfaces must be written as required by the
hardware and operating system used.
The capabilities of the hardware and the imagination of the developer only limit the
application software. For example, one developer may have two compressors. In this
application the developer wants a screen to display the compressor interstage pressure
and temperatures for both machines with various other compressor data. A second
developer has five compressors. He also wants to display the same data, but this time for
all five machines. The only way this is done is through changing the application software
(custom modification).
The developer may write functions to read and display data, log that data to some magnetic
media for storage, change compressor set points, sequence the compressors for efficient
operation and network additional devices, such as pumps, dryers, etc., into the system. All
of these functions require specially written application software for the intended use.
The CMC-MODBUS Interface
Introduction
The CMC can communicate with other devices over a variety of communications standards.
Supported standards, or protocols, include RS-232, IRBUS (Ingersoll-Rand Proprietary),
and Modicon’s MODBUS. The built-in ports on the CMC’s optional Universal
Communication Adapters access communications. The CMC-MODBUS Interface defines
the message structure that a CMC uses to exist on a MODBUS network. This interface will
allow the MODBUS network to gather information and control the compressor.
NOTE
Unless specified otherwise, numerical values (such as addresses, codes, or data) are
expressed as decimal values in the text of this section. They are expressed as
hexadecimal values in the message fields of the examples.
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In order to communicate over other types of
networks, a network adapter must be used. The
information presented in the following sections does
not include MODBUS protocol details like framing
messages and calculating checksums. This detailed
information can be obtained from Schneider
Automation’s MODBUS PROTOCOL Manual,
Chapters 1 through 6. This can be obtained through
the Internet at “www.modicon.com”.
Query
Master
Slave
Device
Address
Device
Address
Function
Code
Function
Code
Data
Address
Byte
Count
Data
Data
CRC
CRC
Serial Modes
MODBUS Controllers can be setup to communicate
on MODBUS networks using either of two
transmission modes: ASCII or RTU. The CMC
supports only the RTU mode. The user must
specify the serial port communication parameters
(baud rate, parity mode, etc.) during configuration of
each CMC. The mode and serial parameters must
be the same for all devices on a MODBUS network.
Response
Figure 22: MODBUS Messages
MODBUS Messages
A MODBUS network uses a master-slave relationship. The CMC always acts as a slave
device. The slave cannot initiate a message, and returns a message (response) only to
queries (reads) that are addressed to them individually. For example, a force coil command
(write to module) that is broadcast to all MODBUS devices would not get a response.
Responses are not returned to broadcast writes from the master.
Device Address
This address is the physical address of the Universal Communication Module (UCM) for the
compressor. This address must be unique in the MODBUS network. The valid range for this
address is 01-FF (hexadecimal). NOTE: 00 (hexadecimal) is reserved for broadcast.
Configuration of the slave address is available through the Ingersoll-Rand Service Tool and
will be provided by a certified Ingersoll-Rand Service Representative.
Function Code
The listing below shows the function codes that are supported by the CMC. Additional detail
about each function is provided in sections that follow.
Function Code
(decimal)
1
2
3
4
5
6
15
16
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Function Code
(hex)
01
02
03
04
05
06
0F
10
Function Name
Read Coil Status
Read Input Status
Read Holding Registers
Read Input Registers
Force Single Coil
Preset Single Register
Force Multiple Coils
Preset Multiple Registers
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Data Addresses
Addresses that contain the data type and a four-digit number are referred to as absolute
(e.g., address 30232, where 3 is the data type for a input register and 0232 or 232 is the
address). Software products at the operator or user level use absolute addresses most
frequently.
The addresses that do not contain the type and are referenced to zero are referred to as
relative (e.g., absolute address 30232 would be relative address 231, remove the data type
3, holding register, and subtract 1 for referencing to zero). All data addresses in MODBUS
messages (typically, behind the scenes at the programming communication level) are
referenced to zero; that is, the first occurrence of a data item is addressed as item number
zero.
Reference
Data Type
0x
1x
3x
4x
Coils
Discrete Inputs
Input Registers
Holding Registers
MODBUS Range
Absolute
Addresses
00001-09999
10001-19999
30001-39999
40001-49999
MODBUS Range
Relative
Addresses
0000-9998
0000-9998
0000-9998
0000-9998
CMC Range
Absolute
Addresses
00001-09000
10001-19000
30001-39000
40001-49000
CMC Range
Relative
Addresses
0000-8999
0000-8999
0000-8999
0000-8999
•
Absolute address for Coil 00127 decimal is relatively addressed as coil 007E hex (126
decimal)
•
Input register with absolute address of 30001 is relatively addressed as register 0000 in
the data address field of the message. The function code field that specifies reading or
writing data already specifies an input register operation; therefore, the 3x reference is
implicit.
•
Holding register with an absolute address of 40108 is relatively addressed as register
006B hex (107 decimal)
Single Module Addresses
The addresses provided in this document are for compressors with a single Base Control
Module.
Multiple Module Addresses
For those systems that require multiple Base Control Modules, the addresses for the first
module will be as provided within this document. The addresses for the second module will
be provided as an engineering submittal.
Data
For both queries and responses, the data is in sixteen bit (two bytes, one word) chunks. For
each two byte word, the left most byte is the most significant. For each byte, the left most
bit is the most significant.
This portion of the message changes with each function code. See the detail that follows for
each function for the specifics of this message component.
Byte Count
The number of bytes contained in the data portion of the message. This is used on both
queries (reads) and responses.
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Cyclical Redundancy Check (CRC)
This portion of the message is used to prevent incorrect data from being used in the Master
or Slave because of communication errors.
Function Details
Function 01 - Read Coil Status
This function reads the state of one or more coils (MODBUS 0x references) in the slave
(CMC Base Control Module). For the CMC, these coils represent the Discrete (Digital)
Outputs, compressor operating state (see the Operator User Interface Status Bar for
definition), any compressor Trip condition and any compressor Alarm condition. If the
function returns a 1, the discrete output is on. If the function returns a 0, the discrete output
is off. Broadcast is not supported. Refer to the table on the next page for MODBUS
Absolute Addresses for each coil supported by the CMC-MODBUS Interface.
Absolute
Address
(decimal)
00187
00188
00189
00190
00191
00192
00193
00194
00195
00196
00197
00198
00199
00200
00201
00202
Relative
Address
(hex)
00-BA
00-BB
00-BC
00-BD
00-BE
00-BF
00-C0
00-C1
00-C2
00-C3
00-C4
00-C5
00-C6
00-C7
00-C8
00-C9
Absolute
Relative
Address
Address
Coil Name - Read Only*
(decimal)
(hex)
Digital Output, Channel 1 (J15-P7,8)
00203
00-CA
Compressor State - Waiting
Digital Output, Channel 2 (J15-P5,6)
00204
00-CB
Compressor State - Coasting
Digital Output, Channel 3 (J15-P3,4)
00205
00-CC
Compressor State - Starting
Digital Output, Channel 4 (J15-P1,2)
00206
00-CD
Compressor State - Not Ready
Digital Output, Channel 5 (J14-P7,8)
00207
00-CE
Compressor State - Ready
Digital Output, Channel 6 (J14-P5,6)
00208
00-CF
Compressor State - Surge Unload
Digital Output, Channel 7 (J14-P3,4)
00209
00-D0
Compressor State - Autodual Unload
Digital Output, Channel 8 (J14-P1,2)
00210
00-D1
Compressor State - Unloading
Digital Output, Channel 9 (J13-P7,8)
00211
00-D2
Compressor State - Unloaded
Digital Output, Channel 10 (J13-P5,6)
00212
00-D3
Compressor State - Min load
Digital Output, Channel 11 (J13-P3,4)
00213
00-D4
Compressor State - Max load
Digital Output, Channel 12 (J13-P1,2)
00214
00-D5
Compressor State - Loading
Digital Output, Channel 13 (J12-P7,8)
00215
00-D6
Compressor State - Loaded
Digital Output, Channel 14 (J12-P5,6)
00216
00-D7
Compressor State - Full Load
Digital Output, Channel 15 (J12-P3,4)
00217
00-D8
Compressor State - Analog Input Failed
Digital Output, Channel 16 (J12-P1,2)
00218
00-D9
Any Compressor Trip
00219
00-DA
Any Compressor Alarm
NOTE: (J15-P7,8) is interpreted as Connector J15, Pins 7 and 8 on the Base Control Module. * IMPORTANT: These coils are defined as
read only. If you decide to write to these coils, unexpected results could occur.
Coil Name - Read Only*
Example: Reading a Single Coil
After reviewing the Electrical Schematic for your compressor, you determine that the digital
output for the prelube pump is located on J12-P7,8 (Channel 13). From the table above, the
Absolute Address is decimal 00199 (Relative Address is hexadecimal 00C6) for the output
in question. Therefore, to read the state of the prelube pump output the following command
is issued (the following data are presented in hexadecimal format):
Device
Address
01
Function
Code
01
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Address
Hi
Lo
00
C6
Number of
Coils
Hi
Lo
00
01
CRC
Lo
1D
Hi
F7
98
CMC TECHNICAL REFERENCE MANUAL
The response from this command is:
Device
Address
01
Function
Code
01
Byte
Count
01
CRC
Data
01
Lo
90
Hi
48
The data (01) means that the discrete output is on, or the prelube pump is running.
Example: Reading Multiple Coils
To read all sixteen digital (discrete) outputs, the following command is sent:
Device
Address
01
Function
Code
01
Address
Hi
Lo
00
BA
Number of
Coils
Hi
Lo
00
10
CRC
Lo
1C
Hi
23
where relative address 00-BA is for digital (discrete) output for Channel 1. The response
from this command is:
Device
Address
01
Function
Code
01
Byte
Count
02
CRC
Data
04-10
Lo
BA
Hi
F0
To determine the state of each output, review the Electrical Schematic for your compressor.
For this example, you determine that the digital output for the prelube pump is located on
J12-P7,8 (Channel 13) and the digital output for the remote trouble contact is J15-P3,4
(Channel 3). The first hexadecimal data byte 04 (0000 0100 binary), represents the states
of the first eight digital (discrete) outputs (8-1). Therefore, for this example 04 means that
Channels 8, 7, 6, 5, 4, 2 and 1 are off and Channel 3 (compressor is in an alarm or trip
condition) is on. For the next eight channels (16-9) the hexadecimal data byte 10 (0001
0000 binary) means that Channels 16, 15, 14, 12, 11, 10 and 9 are off and Channel 13
(prelube pump is running) is on. The following table graphically depicts this example:
Response
Byte 1
Address
8
0
C1
7
0
C0
6
0
BF
5
0
BE
4
0
BD
3
1
BC
2
0
BB
1
0
BA
Response
Byte 2
Address
16
0
C9
15
0
C8
14
0
C7
13
1
C6
12
0
C5
11
0
C4
10
0
C3
9
0
C2
A bit response of 1 means that the output is on and a response of 0 means that the output
is off.
Function 02 - Read Input Status
This function reads the state of one or more discrete inputs (MODBUS 1x references) in the
slave (CMC Base Control Module). For the CMC, these inputs represent the Discrete
(Digital) Inputs. If the function returns a 1, the input is on. If the function returns a 0, the
input is off. Broadcast is not supported. Refer to the table on the next page for MODBUS
Absolute Addresses for each discrete input supported by the CMC-MODBUS Interface.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
99
CMC TECHNICAL REFERENCE MANUAL
Absolute Address
Relative Address
Input Name - Read Only*
(decimal)
(hex)
10171
00-AA
Digital Input, Channel 1 (J4-P2)
10172
00-AB
Digital Input, Channel 2 (J4-P3)
10173
00-AC
Digital Input, Channel 3 (J4-P4)
10174
00-AD
Digital Input, Channel 4 (J4-P5)
10175
00-AE
Digital Input, Channel 5 (J4-P6)
10176
00-AF
Digital Input, Channel 6 (J4-P7)
10177
00-B0
Digital Input, Channel 7 (J4-P8)
10178
00-B1
Digital Input, Channel 8 (J4-P9)
10179
00-B2
Digital Input, Channel 9 (J5-P2)
10180
00-B3
Digital Input, Channel 10 (J5-P3)
10181
00-B4
Digital Input, Channel 11 (J5-P4)
10182
00-B5
Digital Input, Channel 12 (J5-P5)
10183
00-B6
Digital Input, Channel 13 (J5-P6)
10184
00-B7
Digital Input, Channel 14 (J5-P7)
10185
00-B8
Digital Input, Channel 15 (J5-P8)
10186
00-B9
Digital Input, Channel 16 (J5-P9)
NOTE: (J4-P2) is interpreted as Connector J4, Pin 2 on the Base Control Module.
* IMPORTANT: These Digital Inputs are defined as read only. If you decide to
write to these Inputs, unexpected results could occur.
Example: Read Single Discrete Input
After reviewing the Electrical Schematic for your compressor, you determine that the digital
input for emergency stop push button is located on J4-P5 (Channel 4). From the table
above, the Absolute Address is decimal 10174 (Relative Address is hexadecimal 00AD) for
the input in question. Therefore, to read the state of the emergency stop push button the
following command is issued (the following data are presented in hexadecimal format):
Device
Address
01
Function
Code
02
Address
Hi
Lo
00
AD
Number of
Digital Inputs
Hi
Lo
00
01
CRC
Lo
28
Hi
2B
The response from this command is:
Device
Address
01
Function
Code
02
Byte
Count
01
CRC
Data
01
Lo
60
Hi
48
The data (01) means that the input is on, or the emergency stop push button is pressed.
Example: Read Multiple Discrete Inputs
The method for reading multiple Discrete Inputs is the same as reading multiple coils. See
the example for “Reading Multiple Coils”.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
100
CMC TECHNICAL REFERENCE MANUAL
Function 03 - Read Holding Registers
Reads the binary content of holding registers (MODBUS 4x references) in the slave (CMC
Base Control Module). For the CMC, these holding registers contain the Analog Output
values and Analog Alarm and Trip Setpoint values for all CMC inputs and outputs.
Broadcast is not supported.
The CMC is primarily a 32-bit floating-point microprocessor controller. And, since MODBUS
is designed to be a 16-bit system, the CMC supports two methods for determining the value
for each holding register (This also applies to Input Registers.)
NOTE
Since MODBUS is a 16-bit system, the programmer must get two 16-bit numbers and
combine them into one 32-bit floating-point number.
The first method uses two 16-bit integers to represent the integer and fraction part of the
value. The second method uses one 32-bit IEEE floating point number. (NOTE: For those
who would like to only get the 16-bit integer value, this will work well for most inputs;
however, the CMC has some inputs, like vibration, that are typically less than one.
Since the CMC has programmable analog and discrete inputs and outputs, the programmer
must use the electrical schematic supplied with the contract to determine which function
name and units of measure are associated with each input and output.
Refer to the table below for MODBUS Absolute Addresses for each Holding Register
supported by the CMC-MODBUS Interface.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
101
CMC TECHNICAL REFERENCE MANUAL
Holding Register Name - Read/Write
Analog Output, Channel 1 (J3-P1,3)
Analog Output, Channel 2 (J3-P4,6)
Analog Output, Channel 3 (J3-P7,9)
Analog Output, Channel 4 (J3-P10,12)
Analog Input, Channel 1 (J2-P1,3) - High Trip Setpoint
Analog Input, Channel 1 (J2-P1,3) - High Alarm Setpoint
Analog Input, Channel 1 (J2-P1,3) - Low Alarm Setpoint
Analog Input, Channel 1 (J2-P1,3) - Low Trip Setpoint
Analog Input, Channel 2 (J2-P5,7) - High Trip Setpoint
Analog Input, Channel 2 (J2-P5,7) - High Alarm Setpoint
Analog Input, Channel 2 (J2-P5,7) - Low Alarm Setpoint
Analog Input, Channel 2 (J2-P5,7) - Low Trip Setpoint
Analog Input, Channel 3 (J1-P1) - High Trip Setpoint
Analog Input, Channel 3 (J1-P1) - High Alarm Setpoint
Analog Input, Channel 3 (J1-P1) - Low Alarm Setpoint
Analog Input, Channel 3 (J1-P1) - Low Trip Setpoint
Analog Input, Channel 4 (J1-P4) - High Trip Setpoint
Analog Input, Channel 4 (J1-P4) - High Alarm Setpoint
Analog Input, Channel 4 (J1-P4) - Low Alarm Setpoint
Analog Input, Channel 4 (J1-P4) - Low Trip Setpoint
Analog Input, Channel 5 (J1-P5) - High Trip Setpoint
Analog Input, Channel 5 (J1-P5) - High Alarm Setpoint
Analog Input, Channel 5 (J1-P5) - Low Alarm Setpoint
Analog Input, Channel 5 (J1-P5) - Low Trip Setpoint
Analog Input, Channel 6 (J1-P8) - High Trip Setpoint
Analog Input, Channel 6 (J1-P8) - High Alarm Setpoint
Analog Input, Channel 6 (J1-P8) - Low Alarm Setpoint
Analog Input, Channel 6 (J1-P8) - Low Trip Setpoint
Analog Input, Channel 7 (J1-P9) - High Trip Setpoint
Analog Input, Channel 7 (J1-P9) - High Alarm Setpoint
Analog Input, Channel 7 (J1-P9) - Low Alarm Setpoint
Analog Input, Channel 7 (J1-P9) - Low Trip Setpoint
Analog Input, Channel 8 (J1-P12) - High Trip Setpoint
Analog Input, Channel 8 (J1-P12) - High Alarm Setpoint
Analog Input, Channel 8 (J1-P12) - Low Alarm Setpoint
Analog Input, Channel 8 (J1-P12) - Low Trip Setpoint
Analog Input, Channel 9 (J1-P13) - High Trip Setpoint
Analog Input, Channel 9 (J1-P13) - High Alarm Setpoint
Analog Input, Channel 9 (J1-P13) - Low Alarm Setpoint
Analog Input, Channel 9 (J1-P13) - Low Trip Setpoint
Analog Input, Channel 10 (J1-P16) - High Trip Setpoint
Analog Input, Channel 10 (J1-P16) - High Alarm Setpoint
Analog Input, Channel 10 (J1-P16) - Low Alarm Setpoint
Analog Input, Channel 10 (J1-P16) - Low Trip Setpoint
Analog Input, Channel 11 (J1-P17) - High Trip Setpoint
Analog Input, Channel 11 (J1-P17) - High Alarm Setpoint
Analog Input, Channel 11 (J1-P17) - Low Alarm Setpoint
Analog Input, Channel 11 (J1-P17) - Low Trip Setpoint
Analog Input, Channel 12 (J1-P20) - High Trip Setpoint
Analog Input, Channel 12 (J1-P20) - High Alarm Setpoint
Analog Input, Channel 12 (J1-P20) - Low Alarm Setpoint
Analog Input, Channel 12 (J1-P20) - Low Trip Setpoint
Analog Input, Channel 13 (J1-P21) - High Trip Setpoint
Analog Input, Channel 13 (J1-P21) - High Alarm Setpoint
Analog Input, Channel 13 (J1-P21) - Low Alarm Setpoint
Analog Input, Channel 13 (J1-P21) - Low Trip Setpoint
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Signed
16 Bit Exponent
Absolute
Relative
Address
Address
(Decimal)
(hex)
40053
00-34
40055
00-36
40057
00-38
40059
00-3A
40061
00-3C
40063
00-3E
40065
00-40
40067
00-42
40069
00-44
40071
00-46
40073
00-48
40075
00-4A
40077
00-4C
40079
00-4E
40081
00-50
40083
00-52
40085
00-54
40087
00-56
40089
00-58
40091
00-5A
40093
00-5C
40095
00-5E
40097
00-60
40099
00-62
40101
00-64
40103
00-66
40105
00-68
40107
00-6A
40109
00-6C
40111
00-6E
40113
00-70
40115
00-72
40117
00-74
40119
00-76
40121
00-78
40123
00-7A
40125
00-7C
40127
00-7E
40129
00-80
40131
00-82
40133
00-84
40135
00-86
40137
00-88
40139
00-8A
40141
00-8C
40143
00-8E
40145
00-90
40147
00-92
40149
00-94
40151
00-96
40153
00-98
40155
00-9A
40157
00-9C
40159
00-9E
40161
00-A0
40163
00-A2
Unsigned
16 Bit Fraction
Absolute
Relative
Address
Address
(Decimal)
(hex)
40054
00-35
40056
00-37
40058
00-39
40060
00-3B
40062
00-3D
40064
00-3F
40066
00-41
40068
00-43
40070
00-45
40072
00-47
40074
00-49
40076
00-4B
40078
00-4D
40080
00-4F
40082
00-51
40084
00-53
40086
00-55
40088
00-57
40090
00-59
40092
00-5B
40094
00-5D
40096
00-5F
40098
00-61
40100
00-63
40102
00-65
40104
00-67
40106
00-69
40108
00-6B
40110
00-6D
40112
00-6F
40114
00-71
40116
00-73
40118
00-75
40120
00-77
40122
00-79
40124
00-7B
40126
00-7D
40128
00-7F
40130
00-81
40132
00-83
40134
00-85
40136
00-87
40138
00-89
40140
00-8B
40142
00-8D
40144
00-8F
40146
00-91
40148
00-93
40150
00-95
40152
00-97
40154
00-99
40156
00-9B
40158
00-9D
40160
00-9F
40162
00-A1
40164
00-A3
Signed
IEEE 32-Bit Float
Absolute
Relative
Address
Address
(Decimal)
(hex)
43053
0B-EC
43055
0B-EE
43057
0B-F0
43059
0B-F2
43061
0B-F4
43063
0B-F6
43065
0B-F8
43067
0B-FA
43069
0B-FC
43071
0B-FE
43073
0C-00
43075
0C-02
43077
0C-04
43079
0C-06
43081
0C-08
43083
0C-0A
43085
0C-0C
43087
0C-0E
43089
0C-10
43091
0C-12
43093
0C-14
43095
0C-16
43097
0C-18
43099
0C-1A
43101
0C-1C
43103
0C-1E
43105
0C-20
43107
0C-22
43109
0C-24
43111
0C-26
43113
0C-28
43115
0C-2A
43117
0C-2C
43119
0C-2E
43121
0C-30
43123
0C-32
43125
0C-34
43127
0C-36
43129
0C-38
43131
0C-3A
43133
0C-3C
43135
0C-3E
43137
0C-40
43139
0C-42
43141
0C-44
43143
0C-46
43145
0C-48
43147
0C-4A
43149
0C-4C
43151
0C-4E
43153
0C-50
43155
0C-52
43157
0C-54
43159
0C-56
43161
0C-58
43163
0C-5A
102
CMC TECHNICAL REFERENCE MANUAL
Holding Register Name - Read/Write
Analog Input, Channel 14 (J1-P24) - High Trip Setpoint
Analog Input, Channel 14 (J1-P24) - High Alarm Setpoint
Analog Input, Channel 14 (J1-P24) - Low Alarm Setpoint
Analog Input, Channel 14 (J1-P24) - Low Trip Setpoint
Analog Input, Channel 15 (J1-P25) - High Trip Setpoint
Analog Input, Channel 15 (J1-P25) - High Alarm Setpoint
Analog Input, Channel 15 (J1-P25) - Low Alarm Setpoint
Analog Input, Channel 15 (J1-P25) - Low Trip Setpoint
Analog Input, Channel 16 (J1-P28) - High Trip Setpoint
Analog Input, Channel 16 (J1-P28) - High Alarm Setpoint
Analog Input, Channel 16 (J1-P28) - Low Alarm Setpoint
Analog Input, Channel 16 (J1-P28) - Low Trip Setpoint
Analog Input, Channel 17 (J1-P29) - High Trip Setpoint
Analog Input, Channel 17 (J1-P29) - High Alarm Setpoint
Analog Input, Channel 17 (J1-P29) - Low Alarm Setpoint
Analog Input, Channel 17 (J1-P29) - Low Trip Setpoint
Analog Input, Channel 18 (J1-P32) - High Trip Setpoint
Analog Input, Channel 18 (J1-P32) - High Alarm Setpoint
Analog Input, Channel 18 (J1-P32) - Low Alarm Setpoint
Analog Input, Channel 18 (J1-P32) - Low Trip Setpoint
Analog Input, Channel 19 (J1-P33) - High Trip Setpoint
Analog Input, Channel 19 (J1-P33) - High Alarm Setpoint
Analog Input, Channel 19 (J1-P33) - Low Alarm Setpoint
Analog Input, Channel 19 (J1-P33) - Low Trip Setpoint
Analog Input, Channel 20 (J1-P36) - High Trip Setpoint
Analog Input, Channel 20 (J1-P36) - High Alarm Setpoint
Analog Input, Channel 20 (J1-P36) - Low Alarm Setpoint
Analog Input, Channel 20 (J1-P36) - Low Trip Setpoint
Analog Input, Channel 21 (J1-P37) - High Trip Setpoint
Analog Input, Channel 21 (J1-P37) - High Alarm Setpoint
Analog Input, Channel 21 (J1-P37) - Low Alarm Setpoint
Analog Input, Channel 21 (J1-P37) - Low Trip Setpoint
Analog Input, Channel 22 (J1-P40) - High Trip Setpoint
Analog Input, Channel 22 (J1-P40) - High Alarm Setpoint
Analog Input, Channel 22 (J1-P40) - Low Alarm Setpoint
Analog Input, Channel 22 (J1-P40) - Low Trip Setpoint
Analog Input, Channel 23 (J1-P41) - High Trip Setpoint
Analog Input, Channel 23 (J1-P41) - High Alarm Setpoint
Analog Input, Channel 23 (J1-P41) - Low Alarm Setpoint
Analog Input, Channel 23 (J1-P41) - Low Trip Setpoint
Motor Current
User Pressure Setpoint
MinLoad (Throttle Limit, TL)
MaxLoad (High Load Limit, HLL)
Autodual Reload Percent
Autodual Unload Point
Autodual Unload Timer
Pressure Setpoint Ramp Rate
Inlet Valve Unload Position
Start Timer
CT Ratio
Power On Hours
Running Hours
Loaded Hours
Number of Starts
Signed
16 Bit Exponent
Absolute
Relative
Address
Address
(Decimal)
(hex)
40165
00-A4
40167
00-A6
40169
00-A8
40171
00-AA
40173
00-AC
40175
00-AE
40177
00-B0
40179
00-B2
40181
00-B4
40183
00-B6
40185
00-B8
40187
00-BA
40189
00-BC
40191
00-BE
40193
00-C0
40195
00-C2
40197
00-C4
40199
00-C6
40201
00-C8
40203
00-CA
40205
00-CC
40207
00-CE
40209
00-D0
40211
00-D2
40213
00-D4
40215
00-D6
40217
00-D8
40219
00-DA
40221
00-DC
40223
00-DE
40225
00-E0
40227
00-E2
40229
00-E4
40231
00-E6
40233
00-E8
40235
00-EA
40237
00-EC
40239
00-EE
40241
00-F0
40243
00-F2
40267
01-0A
40269
01-0C
40271
01-0E
40273
01-10
40275
01-12
40277
01-14
40279
01-16
40281
01-18
40283
01-1A
40285
01-1C
40287
01-1E
40297
01-28
40299
01-2A
40301
01-2C
40303
01-2E
Unsigned
16 Bit Fraction
Absolute
Relative
Address
Address
(Decimal)
(hex)
40166
00-A5
40168
00-A7
40170
00-A9
40172
00-AB
40174
00-AD
40176
00-AF
40178
00-B1
40180
00-B3
40182
00-B5
40184
00-B7
40186
00-B9
40188
00-BB
40190
00-BD
40192
00-BF
40194
00-C1
40196
00-C3
40198
00-C5
40200
00-C7
40202
00-C9
40204
00-CB
40206
00-CD
40208
00-CF
40210
00-D1
40212
00-D3
40214
00-D5
40216
00-D7
40218
00-D9
40220
00-DB
40222
00-DD
40224
00-DF
40226
00-E1
40228
00-E3
40230
00-E5
40232
00-E7
40234
00-E9
40236
00-EB
40238
00-ED
40240
00-EF
40242
00-F1
40244
00-F3
40268
01-0B
40270
01-0D
40272
01-0F
40274
01-11
40276
01-13
40278
01-15
40280
01-17
40282
01-19
40284
01-1B
40286
01-1D
40288
01-1F
40298
01-29
40300
01-2B
40302
01-2D
40304
01-2F
Signed
IEEE 32-Bit Float
Absolute
Relative
Address
Address
(Decimal)
(hex)
43165
0C-5C
43167
0C-5E
43169
0C-60
43171
0C-62
43173
0C-64
43175
0C-66
43177
0C-68
43179
0C-6A
43181
0C-6C
43183
0C-6E
43185
0C-70
43187
0C-72
43189
0C-74
43191
0C-76
43193
0C-78
43195
0C-7A
43197
0C-7C
43199
0C-7E
43201
0C-80
43203
0C-82
43205
0C-84
43207
0C-86
43209
0C-88
43211
0C-8A
43213
0C-8C
43215
0C-8E
43217
0C-90
43219
0C-92
43221
0C-94
43223
0C-96
43225
0C-98
43227
0C-9A
43229
0C-9C
43231
0C-9E
43233
0C-A0
43235
0C-A2
43237
0C-A4
43239
0C-A6
43241
0C-A8
43243
0C-AA
43267
0C-C2
43269
0C-C4
43271
0C-C6
43273
0C-C8
43275
0C-CA
43277
0C-CC
43279
0C-CE
43281
0C-D0
43283
0C-D2
43285
0C-D4
43287
0C-D6
43297
0C-E0
43299
0C-E2
43301
0C-E4
43303
0C-E6
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Signed
16 Bit Exponent
Absolute
Relative
Holding Register Name - Read/Write
Address
Address
(Decimal)
(hex)
Inlet Valve, MaxLoad, Proportional Constant
40313
01-38
Inlet Valve, MaxLoad, Integral Constant
40315
01-3A
Inlet Valve, MaxLoad, Derivative Constant
40317
01-3C
Inlet Valve, MinLoad, Proportional Constant
40319
01-3E
Inlet Valve, MinLoad, Integral Constant
40321
01-40
Inlet Valve, MinLoad, Derivative Constant
40323
01-42
Inlet Valve, Pressure, Proportional Constant
40325
01-44
Inlet Valve, Pressure, Integral Constant
40327
01-46
Inlet Valve, Pressure, Derivative Constant
40329
01-48
Bypass Valve, Pressure, Proportional Constant
40331
01-4A
Bypass Valve, Pressure, Integral Constant
40333
01-4C
Bypass Valve, Pressure, Derivative Constant
40335
01-4E
Compressor Control Mode; 1=Modulate, 2=Autodual
40339
01-52
NOTE: (J1-P1) is interpreted as Connector J1, Pin 1 on the Base Control Module.
Unsigned
16 Bit Fraction
Absolute
Relative
Address
Address
(Decimal)
(hex)
40314
01-39
40316
01-3B
40318
01-3D
40320
01-3F
40322
01-41
40324
01-43
40326
01-45
40328
01-47
40330
01-49
40332
01-4B
40334
01-4D
40336
01-4F
40340
01-53
Signed
IEEE 32-Bit Float
Absolute
Relative
Address
Address
(Decimal)
(hex)
43313
0C-F0
43315
0C-F2
43317
0C-F4
43319
0C-F6
43321
0C-F8
43323
0C-FA
43325
0C-FC
43327
0C-FE
43329
0D-00
43331
0D-02
43333
0D-04
43335
0D-06
43339
0D-0A
Example: See example for Function 04.
Function 04 - Read Input Registers
Reads the binary content of input registers (MODBUS 3x references) in the slave (CMC
Base Control Module). For the CMC, these input registers refer to the Analog Input values.
Broadcast is not supported.
The CMC is primarily a 32-bit floating-point microprocessor controller. And, since MODBUS
is designed to be a 16-bit system, the CMC supports two methods for determining the value
for each holding register. (This also applies to Input Registers.) The first method uses two
16-bit integers to represent the integer and fraction part of the value. The second method
uses one 32-bit IEEE floating point number.
NOTE
Since MODBUS is a 16-bit system, the programmer must get two 16-bit numbers and
combine them into one 32-bit floating-point number.
For those who would like to only get the 16-bit integer value, this will work well for most
inputs; however, the CMC has some inputs, like vibration, that are typically less than one.
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Signed
Unsigned
Signed
16-Bit Integer
16-Bit Fraction
IEEE 32-Bit Float
Absolute
Relative
Absolute
Relative
Absolute
Relative
Input Register Name - Read Only*
Address
Address
Address
Address
Address
Address
(Decimal)
(hex)
(Decimal)
(hex)
(Decimal)
(hex)
Analog Input, Channel 1 (J2-P1,3)
30003
00-02
30004
00-03
33003
0B-BA
Analog Input, Channel 2 (J2-P5,7)
30005
00-04
30006
00-05
33005
0B-BC
Analog Input, Channel 3 (J1-P1)
30007
00-06
30008
00-07
33007
0B-BE
Analog Input, Channel 4 (J1-P4)
30009
00-08
30010
00-09
33009
0B-C0
Analog Input, Channel 5 (J1-P5)
30011
00-0A
30012
00-0B
33011
0B-C2
Analog Input, Channel 6 (J1-P8)
30013
00-0C
30014
00-0D
33013
0B-C4
Analog Input, Channel 7 (J1-P9)
30015
00-0E
30016
00-0F
33015
0B-C6
Analog Input, Channel 8 (J1-P12)
30017
00-10
30018
00-11
33017
0B-C8
Analog Input, Channel 9 (J1-P13)
30019
00-12
30020
00-13
33019
0B-CA
Analog Input, Channel 10 (J1-P16)
30021
00-14
30022
00-15
33021
0B-CC
Analog Input, Channel 11 (J1-P17)
30023
00-16
30024
00-17
33023
0B-CE
Analog Input, Channel 12 (J1-P20)
30025
00-18
30026
00-19
33025
0B-D0
Analog Input, Channel 13 (J1-P21)
30027
00-1A
30028
00-1B
33027
0B-D2
Analog Input, Channel 14 (J1-P24)
30029
00-1C
30030
00-1D
33029
0B-D4
Analog Input, Channel 15 (J1-P25)
30031
00-1E
30032
00-1F
33031
0B-D6
Analog Input, Channel 16 (J1-P28)
30033
00-20
30034
00-21
33033
0B-D8
Analog Input, Channel 17 (J1-P29)
30035
00-22
30036
00-23
33035
0B-DA
Analog Input, Channel 18 (J1-P32)
30037
00-24
30038
00-25
33037
0B-DC
Analog Input, Channel 19 (J1-P33)
30039
00-26
30040
00-27
33039
0B-DE
Analog Input, Channel 20 (J1-P36)
30041
00-28
30042
00-29
33041
0B-E0
Analog Input, Channel 21 (J1-P37)
30043
00-2A
30044
00-2B
33043
0B-E2
Analog Input, Channel 22 (J1-P40)
30045
00-2C
30046
00-2D
33045
0B-E4
Analog Input, Channel 23 (J1-P41)
30047
00-2E
30048
00-2F
33047
0B-E6
CT Input (J9-P1,2)
30049
00-30
30050
00-31
33049
0B-E8
NOTE: (J1-P1) is interpreted as Connector J1, Pin 1 on the Base Control Module. * IMPORTANT: These Input Registers are defined as read only. If
you decide to write to these Input Registers, unexpected results could occur.
Example: Read Single Channel 16-Bit Integer and Fraction
After reviewing the Electrical Schematic for your compressor, you determine that the analog
input for System Pressure is located on J1-P1 (Channel 3). From the table above, the
Absolute Address is decimal 30007 (Relative Address is hexadecimal 0006) for the input in
question. Therefore, to read the 16 Bit Integer and 16 Bit Fraction for System Pressure the
following command is issued (the following data are presented in hexadecimal format):
Device
Address
01
Function
Code
04
Number of
Registers
Hi
Lo
00
02
Address
Hi
Lo
00
06
CRC
Lo
91
Hi
CA
The response from this command is:
Data
Device
Address
01
Function
Code
04
Byte
Count
04
Reg-1
Hi
00
Reg-2
Lo
64
Hi
13
CRC
Lo
4E
Lo
37
Hi
5F
Register 1 is the Integer portion of the System Pressure or (0064h, 100 decimal). Register 2
is the Fraction portion of the System Pressure or (134Eh, 4942 decimal). Each fraction has
a range between 0 and 9999. So the System Pressure, expressed as a floating point
number is 100.4942 psi.
Example: Read Single Channel IEEE 32-Bit Floating Point Number
To continue with the example, when you decide to get the System Pressure as an IEEE 32
Bit floating point number you must issue the following command:
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Date of Issue: March 24, 2003
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Device
Address
01
Function
Code
04
Number of
Registers
Hi
Lo
00
02
Address
Hi
Lo
0B
BE
CRC
Lo
13
Hi
CB
The response from this command is:
Data
Device
Address
01
Function
Code
04
Byte
Count
04
Reg-1
Hi
42
Reg-2
Lo
DC
Hi
D4
CRC
Lo
C6
Lo
F1
Hi
54
So the System Pressure, expressed as a floating point number is 110.4155731201 psi.
IEEE floating-point numbers are represented in 32 bits as shown below.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
exponent
9
8
7
6
5
4
3
2
1
0
mantissa
sign
Convert hexadecimal registers 1 and 2 (Reg-1, Reg-2) into decimal values ...
Register
1
1
2
2
Byte
Hi
Lo
Hi
Lo
Symbol
R1HB
R1LB
R2HB
R2LB
Hex
42
DC
D4
C6
Decimal
66
220
212
198
Determine the sign (positive = 0 or negative = 1) ...
Sign = (R1HB And 128) / 128, where And is defined as a bit-wise And
Sign = (66 And 128) / 128 = 0
Determine the exponent ...
Exponent = ((R1HB And 127) ∗ 2) + INT(R1LB / 128), where INT is defined as INTEGER
Exponent = ((66 And 127) ∗ 2) + INT(220/128) = 133
Determine the mantissa...
Mantissa = ((((R1LB And 127) ∗ 256) + R2HB) ∗ 256) + R2LB
Mantissa = ((((220 And 127) ∗ 256) + 212) ∗ 256) + 198 = 6083782
Putting the 32 bit IEEE value together...
Value = (-1sign) ∗ (2(exponent - 127)) ∗ ((Mantissa ∗ 2-23) + 1)
Value = (-10) ∗ (2(133- 127)) ∗ ((6083782 ∗ 2-23) + 1) = 110.4155731201
NOTE
When Sign = Exponent = Mantissa = 0, Value = 0. This is a special case for the
above equation.
22204796 Rev. B, Version 3.10
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Date of Issue: March 24, 2003
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Example: Read Multiple Channels
The procedure for reading multiple channels is the same as reading a single channel with
the exception of requesting more data. NOTE: You must read a contiguous group of
registers (channels) for a single command.
Function 05 - Force Single Coil
Forces a single coil (MODBUS 0x references) to either ON or OFF. When broadcast, the
function forces the same coil reference in all attached slaves. Refer to the table below for
MODBUS Absolute Addresses for each coil supported by the CMC-MODBUS Interface.
NOTE
The Force Single Coil command will override the CMC’s current state. The forced
state will remain valid until the CMC next solves the coil. The coil will remain forced if
it is not programmed in the CMC logic.
CAUTION
For all of the following Remote Coils, the compressor’s REMOTE
COMMUNICATIONS DISABLED/ENABLED selector switch must be in the ENABLED
position for these commands to execute. When DISABLED, the CMC ignores (there
is no exception response) these coils being forced ON or OFF.
Absolute
Address
(decimal)
00221
00222
00223
00224
00225
00226
Relative
Address
(hex)
00-DC
00-DD
00-DE
00-DF
00-E0
00-E1
Coil Name - Write Only
Remote Horn Silence (Acknowledge)
Remote Reset
Remote Load
Remote Unload
Remote Start
Remote Stop
Example: Forcing a Coil
For all MODBUS devices, a value of FF 00 hex requests the coil to be ON. A value of 00 00
requests it to be OFF. All other values are illegal and will not affect the coil. NOTE: For the
CMC, forcing the above listed coils OFF is not meaningful because the default state of each
of the above coils is OFF. When using these commands, they should be sent once
(momentary) and the CMC will execute the commands. To remotely reset the compressor,
the following command is issued:
Device
Address
01
Function
Code
05
Address
Hi
Lo
00
DD
Forced
Data
Hi
FF
CRC
Lo
00
Lo
1C
Hi
00
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
107
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The response from this command is identical to the command sent:
Device
Address
01
Function
Code
05
Address
Hi
Lo
00
DD
Number of
Registers
Hi
Lo
FF
00
CRC
Lo
1C
Hi
00
Function 06 - Preset Single Register
Presets a value into a single holding register (MODBUS 4x reference). When broadcast, the
function presets the same register reference in all attached slaves. Refer to the table for the
Holding Register list for the MODBUS Absolute Addresses supported by the CMCMODBUS Interface.
NOTE
The Preset Single Register command will override the CMC’s current state. The
preset value will remain valid in the register until the CMC logic next solves the
register contents. The register's value will remain if it is not programmed in the
controller's logic.
CAUTION
This function can only set a single 16-bit holding register. Since the CMC
operates with 32-bit values, you must use Function 16 (10 Hex) - Preset Multiple
Registers for setting the 32-bit IEEE register values. Also, you may not set the 16-bit
fraction without its 16-bit integer. Therefore, you must use the Preset Multiple
Registers function to send this 32-bit pair. See the examples that follow for
Function 16.
CAUTION
The position of the REMOTE COMMUNICATIONS DISABLED/ENABLED
selector switch is NOT considered when forcing coils or writing registers to the CMC.
Reads and Writes are always enabled. Repeatedly writing a value to a register or
forcing a coil without regard to the position of the switch can effectively disable a local
write. Please use caution when writing registers or forcing coils. The REMOTE
COMMUNICATIONS DISABLED/ENABLED selector switch is typically located on the
front door of the Compressor’s Control Panel.
Example: Presetting a Single Register (16-bit) Integer
To change the integer value for the User Pressure Setpoint (absolute address 40269,
relative address 01-0C) to 100 (00-64 hex) psi, send the following command...
22204796 Rev. B, Version 3.10
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Date of Issue: March 24, 2003
108
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Device
Address
01
Function
Code
06
Address
Hi
Lo
01
0C
Register
Value
Hi
Lo
00
64
CRC
Lo
49
Hi
DE
The response from this command is identical to the command sent:
Device
Address
01
Function
Code
06
Address
Hi
Lo
01
0C
Register
Value
Hi
Lo
00
64
CRC
Lo
49
Hi
DE
Function 15 (0F Hex) - Force Multiple Coils
Forces each coil (MODBUS 0x reference) in a series of contiguous coils to either ON or
OFF. When broadcast, the function forces the same coil references in all attached slaves
(CMC Base Control Modules). Refer to the table for the Coil list for the MODBUS Absolute
Addresses supported by the CMC-MODBUS Interface.
NOTE
The Force Multiple Coils command will override the CMC’s current state. The forced
state will remain valid until the CMC next solves the coil. The coil will remain forced if
it is not programmed in the controller's logic.
CAUTION
The position of the REMOTE COMMUNICATIONS DISABLED/ENABLED
selector switch is NOT considered when forcing coils or writing registers to the CMC.
Reads and Writes are always enabled. Repeatedly writing a value to a register or
forcing a coil without regard to the position of the switch can effectively disable a local
write. Please use caution when writing registers or forcing coils. The REMOTE
COMMUNICATIONS DISABLED/ENABLED selector switch is typically located on the
front door of the Compressor’s Control Panel.
Example: Forcing Multiple Coils
To force a reset (absolute address 00222, relative address DD) and start (absolute address
00225, relative address E0) of the compressor the following command is sent...
Device
Address
01
Function
Code
0F
Address
Hi
Lo
00
DD
Number of
Coils
Hi
Lo
00
04
Number
of Data
Bytes
01
Coil
Data
Lo
09
CRC
Lo
12
Hi
83
The number of contiguous coils is four (00225, 00224, 00223 and 00222). The number of
data bytes is one because we can set up to eight coils in a single byte. The coil data is nine
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
109
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because we want to set the first bit and fourth bit in the byte (0000-1001, the bytes are
numbered right to left). All bits not used are padded with zero.
The response from this command is similar to the command sent except that the number of
data bytes and the coil data themselves are not echoed:
Device
Address
01
Function
Code
0F
Address
Hi
Lo
00
DD
Number of
Coils
Hi
Lo
00
04
CRC
Lo
Hi
C4
32
Function 16 (10 Hex) - Preset Multiple Registers
Presets values into a sequence of contiguous holding registers (MODBUS 4x references).
When broadcast, the function presets the same register references in all attached slaves
(CMC Base Control Modules). Refer to the table for the Input Register list for the MODBUS
Absolute Addresses supported by the CMC-MODBUS Interface.
NOTE
The Preset Multiple Registers command will override the CMC’s current state. The
forced state will remain valid until the CMC next solves the register. The register will
remain forced if it is not programmed in the controller's logic.
CAUTION
The position of the REMOTE COMMUNICATIONS DISABLED/ENABLED
selector switch is NOT considered when forcing coils or writing registers to the CMC.
Reads and Writes are always enabled. Repeatedly writing a value to a register or
forcing a coil without regard to the position of the switch can effectively disable a local
write. Please use caution when writing registers or forcing coils. The REMOTE
COMMUNICATIONS DISABLED/ENABLED selector switch is typically located on the
front door of the Compressor’s Control Panel.
Example: Presetting Holding Registers for 32-bit Values
The difficulty in setting 32-bit values is determining the four data bytes for the number you
want to send. The process required is...
1.
Determine the sign (positive = 0 or negative = 1). This is the first bit.
2.
Divide the decimal value by 2 until the result is less than 2, but greater than 1. Count
the number of iterations required. Add 127 to the number of iterations. This result is the
exponent. Convert this result to binary. These are the next eight bits.
3.
From the result obtained from step 2, subtract 1. Then, multiply this result by 2. If the
result is less than 1, then the value of the first mantissa bit is 0. Otherwise, the
mantissa bit is 1. If the result is greater than or equal to 1, then subtract 1 from the
result and proceed with step 3 until the result is 0 or you have gone through this
process 23 times.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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4.
Combine all 32 bits from the steps above and convert this value to hexadecimal. These
32 bits are the 4 hexadecimal data bytes needed for the command.
As an example, we will start with the decimal value
of 105.4.
1. Since this is a positive number, the first bit is 0.
2. Determine the exponent bits by ...
It took us six iterations to get the result to a number
that is less than two and greater than or equal to one.
Now, we must add 127 for an exponent of 133.
Converting this to binary, the next eight bits are
represented as 10000101.
Iteration
1
2
3
4
5
6
Iteration
3. Determine the mantissa bits by
From the table at right, 0100101100110011001100
represent the next 23 bits.
4. Combining the bits in sign, exponent and then
mantissa order ...
0100-0010-1101-0010-1100-1100-1100-1100
This converts to 42-D2-CC-CC in hexadecimal.
To change the holding registers for user pressure
setpoint (for 32 bit IEEE floating point numbers the
absolute address is 43269, relative address 0C-C4) to
105.4, issue the following command...
Device
Address
01
Function
Code
10
Address
Hi
Lo
0C
C4
Number of
Registers
Hi
Lo
00
02
Number
of Data
Bytes
04
Decimal
105.40000
52.70000
26.35000
13.17500
6.58750
3.29375
Data Bytes for
Register #1
Hi
Lo
42
D2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Decimal
1.646875
1.29375
0.5875
1.175
0.35
0.7
1.4
0.8
1.6
1.2
0.4
0.8
1.6
1.2
0.4
0.8
1.6
1.2
0.4
0.8
1.6
1.2
0.4
Data Bytes for
Register #2
Hi
Lo
CC
CC
/
/
/
/
/
/
2
2
2
2
2
2
Operatio
n
-1*2=
-1*2=
*2=
-1*2=
*2=
*2=
-1*2=
*2=
-1*2=
-1*2=
*2=
*2=
-1*2=
-1*2=
*2=
*2=
-1*2=
-1*2=
*2=
*2=
-1*2=
-1*2=
*2=
Result
52.700000
26.350000
13.175000
6.587500
3.293750
1.646875
=
=
=
=
=
=
Result
Bit
1.29375
0.5875
1.175
0.35
0.7
1.4
0.8
1.6
1.2
0.4
0.8
1.6
1.2
0.4
0.8
1.6
1.2
0.4
0.8
1.6
1.2
0.4
0.8
1
0
1
0
0
1
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
CRC
Lo
4A
Hi
18
The response from this command is similar to the command sent except that the number of
data bytes and the data bytes themselves are not echoed:
Device
Address
01
Function
Code
10
Address
Hi
Lo
0C
C4
Number of
Registers
Hi
Lo
00
02
CRC
Lo
03
Hi
65
NOTE
Sending 32 bit values are typically not necessary. Sending the data as a 16 bit
integer only or a 16 bit integer and 16 bit fraction will satisfy most requirements. Some
systems have 32 bit capability built directly into their products. We have provided this
feature for those systems.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
111
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CAUTION
The position of the REMOTE COMMUNICATIONS DISABLED/ENABLED
selector switch is NOT considered when forcing coils or writing registers to the CMC.
Reads and Writes are always enabled. Repeatedly writing a value to a register or
forcing a coil without regard to the position of the switch can effectively disable a local
write. Please use caution when writing registers or forcing coils. The REMOTE
COMMUNICATIONS DISABLED/ENABLED selector switch is typically located on the
front door of the Compressor’s Control Panel.
Example: Presetting a 16-bit Integer and 16-bit Fraction Holding Register
Change the integer and fraction value for the user pressure setpoint (absolute address
40269, relative address 01-0C) to 110.5 psi. The integer portion of the number 110 (00-6E
hex) is placed at address 40269 and the fraction 0.5 is converted to 5000 (13-88 hex) and
is placed at address 40270 (or the second data byte). To change the register, issue the
following command...
Device
Address
01
Function
Code
10
Address
Hi
Lo
01
0C
Number of
Registers
Hi
Lo
00
02
Number
of Data
Bytes
04
Data Bytes for
Register #1
Hi
Lo
00
6E
Data Bytes for
Register #2
Hi
Lo
13
88
CRC
Lo
92
Hi
E1
The response from this command is similar to the command sent except that the number of
data bytes and the data bytes themselves are not echoed:
Device
Address
01
Function
Code
10
Address
Hi
Lo
01
0C
Number of
Registers
Hi
Lo
00
02
CRC
Lo
80
Hi
37
Exception Responses
Except for broadcast messages, when a master device sends a query to a slave device it
expects a normal response, in all other cases a time out or exception response is returned.
The four possible responses to a the master's query are:
•
If the slave device receives the query without a communication error, and can handle
the query normally, it returns a normal response.
•
If the slave does not receive the query due to a communication error, no response is
returned. The master program will eventually process a time-out condition for the query.
•
If the slave receives the query, but detects a communication error (parity, or CRC), no
response is returned. The master program will eventually process a time-out condition
for the query.
•
If the slave receives the query without a communication error, but cannot handle it (for
example, if the request is to read a nonexistent coil or register), the slave will return an
exception response informing the master of the nature of the error.
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The exception response message has two fields that differentiate it from a normal
response:
Function Code Field
For a normal response, the UCM echoes the function code of the original query in the
function code field of the response. All function codes have their most significant bits set to
zero; therefore, the values are always below 80 hexadecimal. When an exception response
occurs, the UCM sets the most significant bit of the function code to 1. This makes the
function code value in an exception response exactly 80 hexadecimal higher than the value
would be for a normal response.
7
1
Most Significant Bit
6
5
4
0
0
0
3
0
Least Significant Bit
2
1
0
0
0
0
With the function code's most significant bit set, the application program can recognize an
exception response and can examine the data field for the exception code.
Data Field
For a normal response, the UCM will return information in the data field (depending upon
the query message sent). For an exception response, the UCM returns an exception code
in the data field. This defines the UCM’s condition that caused the exception.
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Exception Codes Supported by the CMC Microcontroller
Code
01
Name
Illegal Function
Meaning
The function code received in the query is not an allowable action for the slave. This exception code happens when:
(1) the function code is other than 1, 2, 3, 4, 5, 6, 15 or 16
(2) a message has the incorrect number of bytes for the function specified
02
Illegal Data Address
The data address received in the query is not an allowable address for the slave. This exception code happens when:
(1) the address is not programmed into the Base Control Module (BCM)
(2) the address is outside of the ranges
(a) 00001-00512 for coils
(b) 10001-10512 for discrete inputs
(c) 30001-31024 for integer and fractional analog inputs
(d) 33001-34024 for floating point analog inputs
(e) 40001-41024 for integer and fractional input registers
(f) 43001-44024 for floating point analog input registers
03
Illegal Data Value
A value contained in the query data field is not an allowable value for the slave. This exception code happens when:
(1) the number of coils, discrete inputs, registers or analog inputs is equal to zero
(2) request for more than the maximum number of parameters
(3) the force single coil command, Function 05, is issued and the value is other than FF00 or 0000
(4) the force multiple coil command, Function 15, is issued and the number of bytes does not equal the number of bits
to set
(5) the preset single register command, Function 6, and preset multiple registers commands, Function 16, is issued
and the starting address is not even, the number of registers specified does not correspond to the number of bytes in
the message, the integer part of the number is outside the range –32768 to +32767, the fractional part of the number
is outside of the range 0-9999, or the value is not a valid 32 bit IEEE floating point number
04
Slave Device Failure
An unrecoverable error occurred while the slave was attempting to perform the requested action. This exception code
happens when:
(1) no response from the Base Control Module (BCM) since 800 milliseconds from the time the message was sent …
BCM not wired properly, BCM hardware problem or BCM Module ID not equal to one
(2) when there is an unexpected response from the BCM … this is the default exception response
Maximum Query / Response Parameters
The listing below shows the maximum amount of data that the CMC Microcontroller can
return in a single slave response from a valid MODBUS command.
Function
Dec
Hex
01
01
02
02
03
03
04
04
05
05
06
06
15
0F
16
10
Description
Read Coil Status
Read Input Status
Read Holding Registers
Read Input Registers
Force Single Coil
Preset Single Register
Force Multiple Coils
Preset Multiple Registers
Maximum
Parameters
512 coils
512 inputs
64 registers
64 registers
1 coil
1 register
512 coils
64 registers
CMC Data
The CMC Microcontroller supports several data types. They are coil, integer, fraction and
floating point.
•
Coil - 1 bit, 1 means True or Active, 0 means False or Not Active.
•
Integer - 16 bit signed integer, –32768 to +32767.
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•
Fraction - 16 bit unsigned integer, 0 – 9999, represents the decimal (fractional) part of
the number (1 represents 0.0001, 10 represents 0.0010, 100 represents 0.0100 and
1000 represents 0.1000).
•
Floating Point - 32 bit IEEE number (requires reading two registers to get full number).
For example if the System Pressure input is located on Channel 3 (address 30007) and the
value of the pressure is 100.5 then:
Address 30007 contains 100
Address 30008 contains 5000
Address 33007 contains the high 16 bits of the IEEE value for 100.5
Address 33008 contains the low 16 bits of IEEE value for 100.5
Additionally, the type of data in a location determines the commands that can be used to
access the data. For the previous example of System Pressure addresses 00007, 03007,
10007, 13007, 40007 and 43023 return errors because coil, input status and holding
register commands cannot read input register data.
Scaling and Units of Measure
The MODBUS data are scaled in English engineering units. All pressures are in psi,
temperatures in degrees F, vibrations in mils, and current in amps. For example, when the
CMC Operator User Interface displays the system pressure as 7.73 kg/cm2, the value for
system pressure obtained through MODBUS communications is 110 psi.
Communication Parameters
Configuration of the communication speed (baud rate), parity, number of data bits and
number of stop bits is available through the Ingersoll-Rand Service Tool and will be
provided by a certified Ingersoll-Rand Service Representative.
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The CMC-DF1 Interface
Introduction
Customers may want to communicate to the CMC control systems for remote compressor
control and monitoring through their Allen-Bradley data highway plus (DH+) network.
Adding Allen-Bradley DF1 protocol to the UCM module allows our customers to incorporate
our compressors into their plant-wide Allen-Bradley PLC control system. This
communication capability also provides for flexibility in the customer's compressed air
operation through remote start, stop, and data gathering for preventative maintenance.
The customer or his representative must write system software to suit his individual needs
for remote control and monitoring. Since the customer writes this interface, the system can
be as flexible as the customer desires.
One avenue for communicating with the CMC is via DF1 protocol over a full duplex RS-422
link. This requires an Allen-Bradley interface module 1770-KF2 to link our intelligent RS422A asynchronous device, Universal Communication Module (UCM), to the Allen-Bradley
DH+ network.
The CMC Microcontroller can communicate with other devices over a variety of
communication standards. Supported standards, or protocols, include RS-232, IRBUS
(Ingersoll-Rand Proprietary), Modicon’s MODBUS, and Allen-Bradley DF1. The built-in
ports of the CMC’s Universal Communication Module access communications. This UCMDF1 Interface defines the message structure that a CMC Microcontroller uses to exist on a
DH+ network. This interface will allow the DH+ network to gather information and control
the compressor.
The information presented in these sections that follow do not include the Allen-Bradley
DF1 protocol details. Detailed information can be obtained from “Allen-Bradley Publication
1770-6.5.117 - October 1996” - DF1 Protocol and Command Set Reference Manual and
“Data Highway or Data Highway Plus Asynchronous (RS-232-C or RS-422-A) Interface
Module (Cat. No. 1770-KF2) User’s Manual”.
A DH+ link implements peer-to-peer communication with a token-passing scheme to rotate
mastership among the nodes connected to that link. In order to communicate over AllenBradley DH+ network, an Allen-Bradley 1770-KF2 interface module must be used. The
1770-KF2 always acts as one node on the DH+ network, which translates DH+ messages
to DF1 format, and passes these messages on to the UCM on the RS-422A asynchronous
end, or vice versa.
The following is a picture of 1770-KF2:
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Full-Duplex Protocol
The UCM-DF1 interface only supports the point-to-point full-duplex DF1 protocol, which is
like a two-lane bridge; traffic can travel in both directions at one time. Full-duplex protocol
also provides higher performance applications to get the highest possible throughput.
DF1 Full-Duplex Protocol Message Frames
The following table shows the general format of a DF1 full-duplex message frame. The
control symbols DLE STX bytes are sender symbols indicating the start of a message
frame. The control symbols DLE ETX BCC (CRC) bytes are sender symbols that terminates
a message frame. The bytes comprised in the command data field vary from command to
command.
DLE STX DST
SRC CMD STS TNS
Command Data
DLE
ETX
BCC(CRC)
NOTE
The standard definitions of the control characters used by DF1 full-duplex protocol
are listed below:
Abbreviation
STX
ETX
ENQ
ACK
DLE
NAK
Hexadecimal Value
02
03
05
06
10
0F
DF1 Device Address
Configuration of the DF1 device address is available through the Ingersoll-Rand UCMWizard Tool and will be configured by a certified Ingersoll-Rand Service Representative.
CAUTION
The UCM must be configured to have the same node address as 1770-KF2
interface module. Otherwise, the DF1 messages will not be relayed to the IRBUS port
of the UCM.
Destination (DST) Byte
This byte indicates the destination node address for the message. For a command
message, it will be the address of the 1770-KF2 module. The UCM must have the same
address as the 1770-KF2, which can be configured using the Ingersoll-Rand UCM-wizard
software.
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Source (SRC) Byte
This byte indicates the source node address of the message. If the command is initiated
from an Allen-Bradley PLC, the SRC byte will be the address of the processor module.
Command (CMD) and Function (FNC) Bytes
The CMD byte defines the command type. The FNC byte defines the specific function
under that command type. These bytes together define the activity being performed by the
command message at the destination node. The message format depends on the CMD and
FNC values.
CMD Byte
Bit:
7
0
6
0:Command msg
1:Reply msg
5
0: normal priority(for DH+)
1: high priority(only applies to DH link)
4
0
3 2 1 0
Command code
From the figure above, the CMD byte of a reply message for DH+ network is always 40h
ORed with the CMD byte of its original command message.
Status (STS) Byte - Status Error Code
Bit:
7
6
5
4
Remote Error Nibble
3
2
1
0
Local Error Nibble
Bits 7, 6, 5, and 4 are used to report remote errors - errors that occur when the command
executor at the destination node tries to execute the command message. Bits 3, 2, 1, and 0
are used to report local errors - errors found by the local source node and code 09h through
0Fh are not used. The UCM-DF1 driver uses mainly the higher nibble to report errors occur
in CMC. A special error code with non-zero local error nibble, 3Fh, is used to report errors
caused by illegal CMC data table address or count. The maximum number of data table
entries allowed to be read or set for CMC is 16 currently. If a read command requests more
than 16 data items from CMC, an exception response of 3Fh will be returned.
Following is a list of status error code supported by the UCM-DF1 driver:
Transaction (TNS) Bytes
The two TNS bytes contain a unique 16-bit transaction identifier. Generate this number by
maintaining a 16-bit counter. Increment the counter each time your command initiator
creates a new message, and store the counter value in the two TNS bytes of the new
message. You must use only one TNS counter in a multi-tasking environment.
If the command initiator is an Allen-Bradley PLC, the PLC will maintain the counter
internally. The reply message should have the same TNS value as the original command
message. The UCM-DF1 driver copies the original TNS field of the command message into
the TNS field of the corresponding reply message.
BCC (Block Check Character) and CRC (Cyclic Redundancy Check)
At the end of each DF1 command message, there is a one-byte BCC field, or a two-byte
CRC field for error checking. These bytes allow you to verify the accuracy of each message
frame transmission. SW-1 of 1770-KF2 module allows you to select BCC or CRC error
checking for the command messages sent to CMC. The Ingersoll-Rand UCM-wizard
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software allows you to configure BCC or CRC error checking for the UCM-DF1 driver,
which needs to be the same error checking method as 1770-KF2.
BCC (One Byte)
The BCC field contains the 2’s compliment of the 8-bit sum of all data bytes between DLE
STX and DLE ETX BCC control characters. BCC provides a medium level of data security.
It cannot detect either the transposition of bytes during transmission nor the insertion or
deletion of the value zero within a message frame.
Another way to quickly determine a BCC value, add up the hex values of all data bytes
between DLE STX and DLE ETX BCC in the message frame. If the total is greater than
100h, drop the most significant digit, and then subtract the result from 100h. This gives you
the BCC.
CRC (Two Bytes)
This provides a higher level of data security than BCC but is more difficult to implement. All
the data bytes between DLE STX and DLE ETX CRC plus the ETX byte are used to
calculate the CRC value.
The following explains how to calculate the CRC value:
•
Before starting the calculation, a 16-bit register used to store the CRC value is cleared
to be zero.
•
As a byte is fetched from the data buffer, it is XORed (least-significant bit to the right)
with the right eight bits of the CRC register.
•
The result is placed in the right eight bits of the CRC register.
•
Inserting 0s on the left then shifts the 16-bit CRC Register right eight times. Each time a
1 is shifted out on the right, the CRC register is XORed with a 16-bit constant A0-01h.
•
As each additional byte is fetched, it is included in the value in the register the same
way.
•
After the ETX byte transmitted is also included in the calculation, the CRC calculation is
complete. The 16-bit CRC value is transmitted low byte first then high byte.
Comparing the calculated BCC/CRC bytes with the received BCC/CRC bytes always
validates the DF1 messages received by UCM.
CAUTION
To transmit the data value of 10 hex, you must use the data symbol DLE DLE
(double-stuffing DLEs). However, only one of these DLE bytes is included in the
BCC/CRC calculation. However, if your BCC check sum is 10 hex, send it as DLE
and not DLE DLE.
The rest of this section explains the meaning of the data bytes between DLE STX and DLE
ETX BCC/CRC control characters.
Usually, a command message stripping off the control characters has the following format,
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DST
SRC
CMD
STS
TNS
command specific data packet
a reply message to a read command has the format below,
SRC
DST
CMD
STS
TNS
command specific data packet
a reply message to a write command has the following format,
SRC
DST
CMD
STS
TNS
The DST and SRC bytes of a reply message are formed by interchanging the DST and
SRC bytes of the corresponding command message. The combination of SRC, CMD, and
TNS bytes uniquely identifies every message packet. If all fields are the same, the message
is considered to be a duplicate. The UCM-DF1 driver does not detect duplicate messages.
Scaling and Units of Measure
The MODBUS data are scaled in English engineering units. All pressures are in psi,
temperatures in degrees F, vibrations in mils, and current in amps. For example, when the
CMC Operator User Interface displays the system pressure as 7.73 kg/cm2, the value for
system pressure obtained through MODBUS communications is 110 psi.
Data Addressing
The CMC is primarily a 32-bit floating-point microprocessor controller. We support two
methods for determining the analog data value. These methods are two 16-bit integers
representing the integer and fraction part of the number and one 32-bit IEEE floating point
number. (NOTE: If you use the 16-bit system, you must get two 16-bit numbers and
combine them into one 32-bit floating point number.) The UCM-DF1 interface can prepare
data as either two 16-bit integers or one 32-bit floating point number with respect to the
received DF1 command. The Allen-Bradley PLC floating point format is a subset of IEEE
STD 754-1985.
Accessing data from the CMC via DF1 interface emulates accessing data from a PLC5 or
SLC5/04. In SLC 5/04, each data file can hold up to 256 data elements (element number: 0255) and the file number has to be in the same range (0-255). The UCM-DF1 addressing
scheme uses this file/element structure and complies with the SLC5/04’s limits on file
number and element number. Please see next section for details.
A DF1 command initiator is a device on the DH+ network that initiates the query or set
commands to the CMC. It can be an Allen-Bradley PLC or other device that can
send/receive a PLC5 Typed Read (Write) or SLC Typed Logical Read (Write)
command/response.
CMC as PLC5
As to treating CMC as a PLC5, the command initiator can issue a PLC5 Typed Read
(Write) command to the CMC. Please see the section on Supported Functions for detailed
message format.
For a PLC5 Typed Write command, the data can be sent as either two 16-bit integers or
one 32-bit floating point. If a PLC5 or SLC5/04 issues the command, the setpoint data type
is determined by the local data file type used to store it.
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The PLC5 Typed Read commands for requesting data in integer or float format is exactly
the same messages. The UCM-DF1 driver cannot tell the requested data type from the
command bytes received. Therefore, the returned data type has to be pre-configured in
UCM via the Ingersoll-Rand UCM-wizard tool. Default is the integer type. If a PLC5 or
SLC5/04 issues the command, the local data file used to store the gathered data should be
the same type. Otherwise, you get erroneous data or an error status code due to data type
mismatch.
CMC as SLC5/04
As to treating a CMC as a SLC5/04, the command initiator can issue a SLC Typed Logical
Read (Write) command to the CMC. Please see the section on Supported Functions for
detailed message format.
If the command initiator is another SLC5/04, you can do either integer or float data type.
However, if the command initiator is a PLC5, only integer type is supported for the time
being.
Data File Addressing for PLC5/SLC504
When RSLogix software is used to program message instructions in PLC for sending
read/write commands to the CMC, the target data table address is in the form of either
Fxx:yyy or Nxx:yyy, where xx is the file number (10-14) and yyy (0-255) is the
corresponding CMC data table address. The target file type (F for float, N for integer)
should be consistent with the local file type.
NOTE
File numbers 10-14 are reserved for address only!
The UCM-DF1 interface designates file number 10 for discrete usage (READ ONLY). Each
element represents 16 Boolean data bit-packed together in two bytes. File type can be
either N (integer) or B (bit) type. The following table shows the address in file 10 for discrete
values.
PLC
File
Address
B10:10
B10:11
B10:12
B10:13
CMC Data Table
Address
(decimal)
160-175
176-191
192-207
208-223
15
175
191
207
223
14
174
190
206
222
13
173
189
205
221
12
172
188
204
220
11
171
187
203
219
16 Discretes
Packed as Binary Bits in Two Bytes
10
9
8
7
6
5
170
169
168
167
166
165
186
185
184
183
182
181
202
201
200
199
198
197
218
217
216
215
214
213
4
164
180
196
212
3
163
179
195
211
2
162
178
194
210
1
161
177
193
209
0
160
176
192
208
Bit 10-15 of integer element 10 in data file 10 represents digital input channels 1-6 (CMC
data table address 170-175). Bit 0-9 of integer element 11 represent digital input channels
7-16 (CMC data table address 176-185). Bit 10-15 of integer element 11 represents digital
output channels 1-6 (CMC data table address 186-191). Bit 0-9 of integer element 12
represent digital output channels 7-16 (CMC data table address 192-201). Bit 10-15 of
integer element 11 represents digital output channels 1-6 (CMC data table address 186191). Bit 10-15 of integer element 12 and bit 0-10 of integer element 13 represent various
compressor states (CMC data table address 202-218).
Currently, CMC data table has 512 entries. In order to satisfy the (0-255) limit of elements
per data file for SLC5/04, the CMC data table is divided into two segments; each has 256
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entries. File number 11 is designated to the first 256 entries. File number 12 is for the
second 256 entries. If the CMC data table gets expanded later, the subsequent file number
will be used.
According to the above, N11:170 refers to the 170-th item in the CMC data table, which is
the digital input channel 1. Similarly, N12:170 will be the 426-th = (170+256) item in the
CMC data table. If an invalid file or element number is used, you will get a 3Fh-status error
code. See the status error code section for details.
The number of bytes per element is 2 for integer type and 4 for float type. The assigned
message length in elements for local data file should be a multiple of 2 for integer type. If it
is an odd number, only the 2-byte integer (whole) part will be transmitted for the last data
item.
Since the CMC has programmable analog and discrete inputs and outputs, the programmer
must use the electrical schematic supplied with the machine to determine which function
name and units of measure are associated with each input and output.
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CMC Data Addressing
Refer to the table below for data addresses supported by the UCM-DF1 Interface.
Data
Address
(decimal)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Data
Address
(hex)
01
02
03
04
05
06
07
08
09
0A
0B
0C
0D
0E
0F
10
11
12
13
14
15
16
17
18
19
1A
1B
1C
1D
1E
1F
32
33
34
35
36
37
38
39
40
41
20
21
22
23
24
25
26
27
28
29
Analog Input, Ch 1 (J2-P1,3)
Analog Input, Ch 2 (J2-P5,7)
Analog Input, Ch 3 (J1-P1)
Analog Input, Ch 4 (J1-P4)
Analog Input, Ch 5 (J1-P5)
Analog Input, Ch 6 (J1-P8)
Analog Input, Ch 7 (J1-P9)
Analog Input, Ch 8 (J1-P12)
Analog Input, Ch 9 (J1-P13)
Analog Input, Ch 10 (J1-P16)
Analog Input, Ch 11 (J1-P17)
Analog Input, Ch 12 (J1-P20)
Analog Input, Ch 13 (J1-P21)
Analog Input, Ch 14 (J1-P24)
Analog Input, Ch 15 (J1-P25)
Analog Input, Ch 16 (J1-P28)
Analog Input, Ch 17 (J1-P29)
Analog Input, Ch 18 (J1-P32)
Analog Input, Ch 19 (J1-P33)
Analog Input, Ch 20 (J1-P36)
Analog Input, Ch 21 (J1-P37)
Analog Input, Ch 22 (J1-P40)
Analog Input, Ch 23 (J1-P41)
CT Input (J9-P1,2)
Reserved
Analog Output, Ch 1 (J3-P1,3)
Analog Output, Ch 2 (J3-P4,6)
Analog Output, Ch 3 (J3-P7,9)
Analog Output, Ch 4 (J3-P10,12)
Analog Input, Ch 1 (J2-P1,3) – Hi Trip Setpoint
Analog Input, Ch 1 (J2-P1,3) – Hi Alarm Setpoint
Data
Address
(decimal)
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
Data
Address
(hex)
2A
2B
2C
2D
2E
2F
30
31
32
33
34
35
36
37
38
39
3A
3B
3C
3D
3E
3F
40
41
42
43
44
45
46
47
48
Analog Input, Ch 4 (J1-P4) – Hi Trip Setpoint
Analog Input, Ch 4 (J1-P4) – Hi Alarm Setpoint
Analog Input, Ch 4 (J1-P4) - Lo Alarm Setpoint
Analog Input, Ch 4 (J1-P4) - Lo Trip Setpoint
Analog Input, Ch 5 (J1-P5) - Hi Trip Setpoint
Analog Input, Ch 5 (J1-P5) - Hi Alarm Setpoint
Analog Input, Ch 5 (J1-P5) - Lo Alarm Setpoint
Analog Input, Ch 5 (J1-P5) - Lo Trip Setpoint
Analog Input, Ch 6 (J1-P8) - Hi Trip Setpoint
Analog Input, Ch 6 (J1-P8) - Hi Alarm Setpoint
Analog Input, Ch 6 (J1-P8) - Lo Alarm Setpoint
Analog Input, Ch 6 (J1-P8) - Lo Trip Setpoint
Analog Input, Ch 7 (J1-P9) - Hi Trip Setpoint
Analog Input, Ch 7 (J1-P9) - Hi Alarm Setpoint
Analog Input, Ch 7 (J1-P9) - Lo Alarm Setpoint
Analog Input, Ch 7 (J1-P9) - Lo Trip Setpoint
Analog Input, Ch 8 (J1-P12) - Hi Trip Setpoint
Analog Input, Ch 8 (J1-P12) - Hi Alarm Setpoint
Analog Input, Ch 8 (J1-P12) - Lo Alarm Setpoint
Analog Input, Ch 8 (J1-P12) - Lo Trip Setpoint
Analog Input, Ch 9 (J1-P13) - Hi Trip Setpoint
Analog Input, Ch 9 (J1-P13) - Hi Alarm Setpoint
Analog Input, Ch 9 (J1-P13) - Lo Alarm Setpoint
Analog Input, Ch 9 (J1-P13) - Lo Trip Setpoint
Analog Input, Ch 10 (J1-P16) - Hi Trip Setpoint
Analog Input, Ch 10 (J1-P16) - Hi Alarm Setpoint
Analog Input, Ch 10 (J1-P16) - Lo Alarm Setpoint
Analog Input, Ch 10 (J1-P16) - Lo Trip Setpoint
Analog Input, Ch 11 (J1-P17) - Hi Trip Setpoint
Analog Input, Ch 11 (J1-P17) - Hi Alarm Setpoint
Analog Input, Ch 11 (J1-P17) - Lo Alarm Setpoint
Analog Input, Ch 1 (J2-P1,3) – Lo Alarm Setpoint
Analog Input, Ch 1 (J2-P1,3) – Lo Trip Setpoint
Analog Input, Ch 2 (J2-P5,7) – Hi Trip Setpoint
Analog Input, Ch 2 (J2-P5,7) – Hi Alarm Setpoint
Analog Input, Ch 2 (J2-P5,7) – Lo Alarm Setpoint
Analog Input, Ch 2 (J2-P5,7) – Lo Trip Setpoint
Analog Input, Ch 3 (J1-P1) – Hi Trip Setpoint
Analog Input, Ch 3 (J1-P1) – Hi Alarm Setpoint
Analog Input, Ch 3 (J1-P1) – Lo Alarm Setpoint
Analog Input, Ch 3 (J1-P1) – Lo Trip Setpoint
73
74
75
76
77
78
79
80
81
82
49
4A
4B
4C
4D
4E
4F
50
51
52
Analog Input, Ch 11 (J1-P17) - Lo Trip Setpoint
Analog Input, Ch 12 (J1-P20) - Hi Trip Setpoint
Analog Input, Ch 12 (J1-P20) - Hi Alarm Setpoint
Analog Input, Ch 12 (J1-P20) - Lo Alarm Setpoint
Analog Input, Ch 12 (J1-P20) - Lo Trip Setpoint
Analog Input, Ch 13 (J1-P21) - Hi Trip Setpoint
Analog Input, Ch 13 (J1-P21) - Hi Alarm Setpoint
Analog Input, Ch 13 (J1-P21) - Lo Alarm Setpoint
Analog Input, Ch 13 (J1-P21) - Lo Trip Setpoint
Analog Input, Ch 14 (J1-P24) - Hi Trip Setpoint
Description
Description
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
123
CMC TECHNICAL REFERENCE MANUAL
Data
Address
(decimal)
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
Data
Address
(hex)
53
54
55
56
57
58
59
5A
5B
5C
5D
5E
5F
60
61
62
63
64
65
66
67
68
69
6A
6B
6C
6D
6E
6F
70
71
72
73
74
75
76
77
78
79
7A
7B
7C
7D
7E
7F
80
81
82
83
84
85
86
87
88
89
8A
8B
8C
8D
Description
Analog Input, Ch 14 (J1-P24) - Hi Alarm Setpoint
Analog Input, Ch 14 (J1-P24) - Lo Alarm Setpoint
Analog Input, Ch 14 (J1-P24) - Lo Trip Setpoint
Analog Input, Ch 15 (J1-P25) - Hi Trip Setpoint
Analog Input, Ch 15 (J1-P25) - Hi Alarm Setpoint
Analog Input, Ch 15 (J1-P25) - Lo Alarm Setpoint
Analog Input, Ch 15 (J1-P25) - Lo Trip Setpoint
Analog Input, Ch 16 (J1-P28) - Hi Trip Setpoint
Analog Input, Ch 16 (J1-P28) - Hi Alarm Setpoint
Analog Input, Ch 16 (J1-P28) - Lo Alarm Setpoint
Analog Input, Ch 16 (J1-P28) - Lo Trip Setpoint
Analog Input, Ch 17 (J1-P29) - Hi Trip Setpoint
Analog Input, Ch 17 (J1-P29) - Hi Alarm Setpoint
Analog Input, Ch 17 (J1-P29) - Lo Alarm Setpoint
Analog Input, Ch 17 (J1-P29) - Lo Trip Setpoint
Analog Input, Ch 18 (J1-P32) - Hi Trip Setpoint
Analog Input, Ch 18 (J1-P32) - Hi Alarm Setpoint
Analog Input, Ch 18 (J1-P32) - Lo Alarm Setpoint
Analog Input, Ch 18 (J1-P32) - Lo Trip Setpoint
Analog Input, Ch 19 (J1-P33) - Hi Trip Setpoint
Analog Input, Ch 19 (J1-P33) - Hi Alarm Setpoint
Analog Input, Ch 19 (J1-P33) - Lo Alarm Setpoint
Analog Input, Ch 19 (J1-P33) - Lo Trip Setpoint
Analog Input, Ch 20 (J1-P36) - Hi Trip Setpoint
Analog Input, Ch 20 (J1-P36) - Hi Alarm Setpoint
Analog Input, Ch 20 (J1-P36) - Lo Alarm Setpoint
Analog Input, Ch 20 (J1-P36) - Lo Trip Setpoint
Analog Input, Ch 21 (J1-P37) - Hi Trip Setpoint
Analog Input, Ch 21 (J1-P37) - Hi Alarm Setpoint
Analog Input, Ch 21 (J1-P37) - Lo Alarm Setpoint
Analog Input, Ch 21 (J1-P37) - Lo Trip Setpoint
Analog Input, Ch 22 (J1-P40) - Hi Trip Setpoint
Analog Input, Ch 22 (J1-P40) - Hi Alarm Setpoint
Analog Input, Ch 22 (J1-P40) - Lo Alarm Setpoint
Analog Input, Ch 22 (J1-P40) - Lo Trip Setpoint
Analog Input, Ch 23 (J1-P41) - Hi Trip Setpoint
Analog Input, Ch 23 (J1-P41) - Hi Alarm Setpoint
Analog Input, Ch 23 (J1-P41) - Lo Alarm Setpoint
Analog Input, Ch 23 (J1-P41) - Lo Trip Setpoint
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Surge Pressure Rate
Surge Current Rate
Motor Current
User Pressure Setpoint
MinLoad (Throttle Limit, TL)
MaxLoad (High Load Limit, HLL)
Autodual Reload Percent
Autodual Unload Point
Autodual Unload Timer
Pressure Setpoint Ramp Rate
Inlet Valve Unload Position
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Data
Address
(decimal)
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
Data
Address
(hex)
8E
8F
90
91
92
93
94
95
96
97
98
99
9A
9B
9C
9D
9E
9F
A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
AA
AB
AC
AD
AE
AF
B0
B1
B2
B3
B4
B5
B6
B7
B8
B9
BA
BB
BC
BD
BE
BF
C0
C1
C2
C3
C4
C5
C6
C7
C8
Description
Start Timer
CT Ratio
Reserved
Reserved
Reserved
Reserved
Power on hours
Running Hours
Loaded Hours
Number of starts
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Inlet Valve Proportional Constant
Inlet Valve Integral Constant
Reserved
Bypass Valve Proportional Constant
Bypass Valve Integral Constant
Reserved
Reserved
Compressor Control Mode
Digital Input, Ch 1 (J4-P2)
Digital Input, Ch 2 (J4-P3)
Digital Input, Ch 3 (J4-P4)
Digital Input, Ch 4 (J4-P5)
Digital Input, Ch 5 (J4-P6)
Digital Input, Ch 6 (J4-P7)
Digital Input, Ch 7 (J4-P8)
Digital Input, Ch 8 (J4-P9)
Digital Input, Ch 9 (J5-P2)
Digital Input, Ch 10 (J5-P3)
Digital Input, Ch 11 (J5-P4)
Digital Input, Ch 12 (J5-P5)
Digital Input, Ch 13 (J5-P6)
Digital Input, Ch 14 (J5-P7)
Digital Input, Ch 15 (J5-P8)
Digital Input, Ch 16 (J5-P9)
Digital Output, Ch 1 (J15-P7,8)
Digital Output, Ch 2 (J15-P5,6)
Digital Output, Ch 3 (J15-P3,4)
Digital Output, Ch 4 (J15-P1,2)
Digital Output, Ch 5 (J14-P7,8)
Digital Output, Ch 6 (J14-P5,6)
Digital Output, Ch 7 (J14-P3,4)
Digital Output, Ch 8 (J14-P1,2)
Digital Output, Ch 9 (J13-P7,8)
Digital Output, Ch 10 (J13-P5,6)
Digital Output, Ch 11 (J13-P3,4)
Digital Output, Ch 12 (J13-P1,2)
Digital Output, Ch 13 (J12-P7,8)
Digital Output, Ch 14 (J12-P5,6)
Digital Output, Ch 15 (J12-P3,4)
124
CMC TECHNICAL REFERENCE MANUAL
Data
Address
(decimal)
201
202
203
204
205
206
207
208
209
210
211
212
Data
Address
(hex)
C9
CA
CB
CC
CD
CE
CF
D0
D1
D2
D3
D4
Data
Address
(decimal)
213
214
215
216
217
218
220
221
222
223
224
225
Description
Digital Output, Ch 16 (J12-P1,2)
Compressor State - Waiting
Compressor State - Coasting
Compressor State – Starting
Compressor State - Not Ready
Compressor State - Ready
Compressor State - Surge Unload
Compressor State - Autodual Unload
Compressor State - Unloading
Compressor State - Unloaded
Compressor State - Min load
Compressor State - Max load
Data
Address
(hex)
D5
D6
D7
D8
D9
DA
DC
DD
DE
DF
E0
E1
Description
Compressor State - Loading
Compressor State - Loaded
Compressor State - Full Load
Compressor State - Analog Input Failed
Any Compressor Trip
Any Compressor Alarm
Remote Acknowledge
Remote Reset
Remote Load
Remote Unload
Remote Start
Remote Stop
Supported Functions
The listing below shows the DF1 commands supported by the CMC Microcontroller.
Command
Code
(hex)
0F
0F
0F
0F
Function
Code
(hex)
68
67
A2
AA
Function Name
PLC5 Typed Read
PLC5 Typed Write
SLC Typed Logical Read
SLC Typed Logical Write
Command 0F/Function 68 - PLC5 Typed Read
The CMC is treated as a PLC5 when this command is issued. This command reads a block
of data from CMC starting at a specified data table address.
As to the format of floating point number, Allen-Bradley DF1 protocol always put low byte
first then high byte, low word first then high word, which is different from the UCMMODBUS protocol. The byte format for a floating point value, 105.4, is differentiated
between the two interfaces as below (Byte 1 to 4 is in the order of transmission):
Protocol
UCM-MODBUS
UCM-DF1
Floating Point Byte Representation
Byte 1
Byte 2
Byte 3
Byte 4
42
D2
CC
CD
CD
CC
D2
42
Example: Reading an Analog Input
After reviewing the Electrical Schematic for your compressor, you determine that the analog
input for system pressure is located on J1-P1 (Channel 3). From the CMC data table above,
the address is 03h. The UCM should be configured to represent data type as desired.
Following is a table illustrating how the PLC5 system address is mapped to the CMC data
table address.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
125
CMC TECHNICAL REFERENCE MANUAL
CMC
Data
Address
3
254
255
256
259
PLC5
Target Data
Table Address
N11:3
N11:254
N11:255
N12:0
N12:3
07
07
07
07
07
00
00
00
00
00
PLC5 System Address
Element
File
Number
0B
03
0B
FE
0B
FF
FF
0C
00
0C
03
00
As 16-Bit Integer and Fraction
To get the reading of system pressure as 16-bit integer and 16-bit fraction, the following
command is issued (data are presented in hexadecimal format):
DLE
STX
DST
SRC
CMD
STS
10
02
0D
11
0F
00
TNS
21
FNC
BD
68
Packet
Offset
00
00
Total
Trans
02
00
PLC5 System Address
07
00
0B
03
Size
02
DLE
ETX
BCC
00
10
03
74
DLE
10
ETX
03
BCC
03
The response from this command is:
DLE
10
STX
02
DST
11
SRC
0D
CMD
4F
STS
00
TNS
21
BD
A
99
09
B
05
42
64
00
5C
09
In the response above, the first two bytes (low byte first then high byte) in field B is the
integer portion of the system pressure (00-64h, 100 decimal). The second two bytes in field
B are the fraction portion of the system pressure (09-5Ch, 2396 decimal). Each fraction has
a range between 0 and 9999. So the system pressure, expressed as a floating-point
number, is 100.2396 PSIG.
The following table contains a list of data types and the ID value of each supported by
Allen-Bradley DF1 protocol:
Data Type ID
1
2
3
4
5
6
7
8
9
15
16
Data Type
bit
bit string
byte (or character) string
integer
Allen-Bradley timer
Allen-Bradley counter
Allen-Bradley general control structure
IEEE floating point
array of similar elements
address data
binary-coded decimal (BCD)
The first byte, 99h, in field A of the above response message is a flag byte, which has the
format below:
Bit:
7
1
Data Type ID
6
5
0
0
4
1
3
1
Data Type Size
2
1
0
0
0
1
If the data type ID is greater than 7, set bit 7 of this flag byte to 1 and insert the number of
bytes to follow that contains the data type ID value in bits 4, 5, and 6. These additional ID
bytes follow directly after the flag byte. In the above response message, the additional one
byte is 09h, which means array of similar elements.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
126
CMC TECHNICAL REFERENCE MANUAL
If the data type defined uses more than 7 bytes for each data element, enter 1 in bit 3 of the
flag byte and enter the number of bytes to follow that contains the number of bytes used for
each data element. These additional size bytes follow the flag byte and any ID bytes.
The individual bytes in field A and B of the above response message is explained in the
following table:
Field
Byte (hex)
99
09
05
42
A
Definition
flag byte
data type ID byte: array of similar elements
number of bytes to follow
descriptor byte
4: type ID for integer
2: two bytes per element
64
00
5C
09
B
4 data bytes
As IEEE 32-Bit Floating Point Number
If the UCM is configured to read data as floating point, the following command is sent:
DLE
STX
DST
SRC
CMD
STS
10
02
0D
11
0F
00
TNS
21
FNC
BD
68
Packet
Offset
00
00
Total
Trans
01
00
PLC5 System Address
07
00
0B
Size
03
01
00
DLE
ETX
10
03
BCC
The response from this command is:
DLE
10
STX
02
DST
11
SRC
0D
CMD
4F
STS
00
TNS
21
BD
99
09
A
06
B
94
08
C6
D4
DC
DLE
10
42
ETX
03
BCC
The individual bytes in field A and B of the above response message is explained in the
table below:
Field
A
B
Byte (hex)
99
09
06
94
08
C6
D4
DC
42
means
flag byte
data type ID byte: array of similar elements
number of bytes to follow
descriptor byte
9: one byte to follow
4: four bytes per element
type ID for floating point
4 data bytes
After the proper byte swapping, the system pressure (42-DC-D4-C6), expressed as a
floating point number is 110.4155731201 PSIG.
IEEE floating-point numbers are represented in 32 bits as shown below.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
exponent
9
8
7
6
5
4
3
2
1
0
mantissa
sign
Convert hexadecimal words 1 and 2 (W1, W2) into decimal values ...
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
127
CMC TECHNICAL REFERENCE MANUAL
Word
Lo 1
Lo 1
Hi 2
Hi 2
Byte
Lo
Hi
Lo
Hi
Symbol
W1LB
W1HB
W2LB
W2HB
Hex
C6
D4
DC
42
Decimal
198
212
220
66
Determine the sign (positive = 0 or negative = 1) ...
Sign = (W2HB And 128) / 128, where And is defined as a bit-wise And
Sign = (66 And 128) / 128 = 0
Determine the exponent ...
Exponent = ((W2HB And 127) * 2) + INT (W2LB / 128), where INT is defined as
INTEGER
Exponent = ((66 And 127) * 2) + INT (220/128) = 133
Determine the mantissa...
Mantissa = ((((W2LB And 127) * 256) + W1HB) * 256) + W1LB
Mantissa = ((((220 And 127) * 256) + 212) * 256) + 198 = 6083782
Putting the 32 bit IEEE value together...
Value = (-1sign) * (2(exponent - 127)) * ((Mantissa * 2-23) + 1)
Value = (-10) * (2(133- 127)) * ((6083782 * 2-23) + 1) = 110.4155731201
NOTE
When Sign = Exponent = Mantissa = 0, Value = 0. This is a special case for the
above equation.
Example: Read Multiple Analog Channels
The procedure for reading multiple channels is the same as reading a single channel with
the exception of requesting more data. The message length in elements should be set as
desired but no more than 16 data at a time, because IRBUS can handle at most 16 data in
one query for the time being.
NOTE
A contiguous group of data (channels) must be read for a single command.
Example: Reading a Discrete Value
Reading discrete values from file number 11 or higher is the same as reading analog data.
To read a digital output (Channel 3, 188h) as a two-byte integer, the following command is
sent:
DLE
STX
DST
SRC
CMD
STS
10
02
0D
11
0F
00
TNS
A1
C2
FNC
68
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Packet
Offset
00
00
Total
Trans
01
00
PLC5 System
Address
07
00
0B
BC
Size
01
00
DLE
ETX
BCC
10
03
38
128
CMC TECHNICAL REFERENCE MANUAL
The response to this command is:
DLE
10
STX
02
DST
11
SRC
0D
CMD
4F
STS
00
TNS
A1
C2
A
99
09
B
03
42
01
DLE
10
00
ETX
03
BCC
48
Example: Reading Multiple Discrete Values
To read digital output channels 1-6 as integers, the following command is sent:
DLE
STX
DST
SRC
CMD
STS
10
02
0D
11
0F
00
TNS
41
FNC
17
Packet
Offset
00
00
68
Total
Trans
0C
00
PLC5 System
Address
07
00
0B
BA
Size
0C
00
DLE
ETX
BCC
10
03
2F
The response to this command is:
DLE
10
STX
02
DST
11
SRC
0D
CMD
4F
STS
00
TNS
41
17
A
99
09
B
19
42
00
00
00
00
B
00
00
00
00
00
00
00
00
00
00
00
00
DLE
10
00
00
00
ETX
03
00
01
00
00
00
BCC
3D
Example: Reading Bit-Packed Discrete Data
Reading discrete values from file number 10 is to read the 16 bit-packed discrete values in
a two-byte integer format. When the following command is sent,
DLE
STX
DST
SRC
10
02
0D
11
CMD
STS
0F
00
TNS
61
C4
FNC
68
Packet
Offset
00
00
Total
Trans
01
00
PLC5 System Address
07
00
0A
Size
0B
01
00
DLE
ETX
BCC
10
03
28
the response from this command is:
DLE
10
STX
02
DST
11
SRC
0D
CMD
4F
STS
00
TNS
61
C4
A
99
09
03
42
28
B
10
10
DLE
10
ETX
03
BCC
4F
NOTE
The data value 10h in field B is transmitted as 10h 10h to be distinguished from the
control character DLE. Please see the DF1 Full-Duplex Protocol Message Frames
section for more details.
In the above example, the local data file type can be either bit or integer types. Local data
element B10:11 covers CMC data table address 176-191. Bit 10-15 is for digital output
channels 1-6. You can determine the remote trouble contact (Channel 3, J15-P3,4) by bit
12 in the returned integer. The table below graphically depicts the individual bit value for the
returned two-byte integer.
Response (hex)
Byte 1
Bit
CMC Data Address
28
Bit
CMC Data Address
Byte 2
10
7
183
0
15
191
0
6
182
0
14
190
0
5
181
1
13
189
0
4
180
0
12
188
1
3
179
1
11
187
0
2
178
0
10
186
0
1
177
0
9
185
0
0
176
0
8
184
0
A bit response of 1 means that the output is ON and a response of 0 means that the output
is OFF.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
129
CMC TECHNICAL REFERENCE MANUAL
Command 0F/Function 67 - PLC5 Typed Write
CAUTION
The position of the REMOTE COMMUNICATIONS DISABLED/ENABLED
selector switch is NOT considered when forcing coils or writing registers to the CMC.
Reads and Writes are always enabled. Repeatedly writing a value to a register or
forcing a coil without regard to the position of the switch can effectively disable a local
write. Please use caution when writing registers or forcing coils. The REMOTE
COMMUNICATIONS DISABLED/ENABLED selector switch is typically located on the
front door of the Compressor’s Control Panel.
The CMC is treated as a PLC5 when this command is issued. This command writes data to
the CMC starting at the specified data table address. You can write to a setpoint with either
an integer or floating point number.
Example: Presetting Analog Setpoints for 32-bit Values
To write 105.4 PSIG as a floating point number to the user pressure setpoint (CMC data
table address, 86h), issue the following command:
DLE
STX
DST
SRC
CMD
STS
10
02
0D
11
0F
00
81
CE
67
A
06
94
08
CD
CC
99
09
TNS
FNC
Packet
Offset
00
00
B
D2
42
Total
Trans
01
00
DLE
10
ETX
03
PLC5 System
Address
07
00
0B
86
BCC
93
The response from this command is:
DLE
10
STX
02
DST
11
SRC
0D
CMD
4F
STS
00
TNS
81
CE
DLE
10
ETX
03
BCC
44
The difficulty in setting 32-bit values is determining the four data bytes for the number you
want to send. The process required is ...
1. Determine the sign (positive = 0 or negative = 1). This is the first bit.
2. Divide the decimal value by 2 until the result is less than 2, but greater than 1. Count
the number of iterations required. Add 127 to the number of iterations. This result is the
exponent. Convert this result to binary. These are the next eight bits.
3. From the result obtained from step 2, subtract 1. Then, multiply this result by 2. If the
result is less than 1, then the value of the first mantissa bit is 0. Otherwise, the mantissa
bit is 1. If the result is greater than or equal to 1, then subtract 1 from the result and
proceed with step 3 until the result is 0 or you have gone through this process 23 times.
4. Combine all 32 bits from the steps above and convert this value to hexadecimal. These
32 bits are the 4 hexadecimal data bytes needed for the command.
As an example, we will start with the decimal value of 105.4.
1. Since this is a positive number, the first bit is 0.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
130
CMC TECHNICAL REFERENCE MANUAL
2. Determine the exponent bits by ...
Iteration
1
2
3
4
5
6
Decimal
105.40000
52.70000
26.35000
13.17500
6.58750
3.29375
/
/
/
/
/
/
2
2
2
2
2
2
=
=
=
=
=
=
Result
52.700000
26.350000
13.175000
6.587500
3.293750
1.646875
It took us six iterations to get the result to a number that is less than two and greater than or
equal to one. Now, we must add 127 for an exponent of 133. Converting this to binary, the
next eight bits are represented as 10000101.
3. Determine the mantissa bits by ...
Iteration
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Decimal
1.646875
1.29375
0.5875
1.175
0.35
0.7
1.4
0.8
1.6
1.2
0.4
0.8
1.6
1.2
0.4
0.8
1.6
1.2
0.4
0.8
1.6
1.2
0.4
Operation Result
- 1 * 2 = 1.29375
-1*2=
0.5875
*2=
1.175
-1*2=
0.35
*2=
0.7
*2=
1.4
-1*2=
0.8
*2=
1.6
-1*2=
1.2
-1*2=
0.4
*2=
0.8
*2=
1.6
-1*2=
1.2
-1*2=
0.4
*2=
0.8
*2=
1.6
-1*2=
1.2
-1*2=
0.4
*2=
0.8
*2=
1.6
-1*2=
1.2
-1*2=
0.4
*2=
0.8
Bit
1
0
1
0
0
1
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
From the table above, 10100101100110011001100 represent the next 23 bits.
4. Combining the bits in sign, exponent and then mantissa order ...
0100-0010-1101-0010-1100-1100-1100-1100
This converts to 42-D2-CC-CC in hexadecimal. To conform to DF1 floating point format, the
bytes are swapped as CC-CC-D2-42.
Example: Presetting a 16-bit Integer and 16-bit Fraction Analog Setpoint
To change the integer and fraction value for the user pressure setpoint to 105.4 PSIG,
issue the command below. The integer portion of the number 105 (00-69h) and the fraction
0.4 is converted to 4000 (0F-A0h). These four bytes are placed in field B in the order of (6900-A0-0F).
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
131
CMC TECHNICAL REFERENCE MANUAL
DLE
STX
DST
SRC
CMD
STS
10
02
0D
11
0F
00
TNS
41
FNC
D0
67
A
99
09
Packet
Offset
00
00
B
05
42
69
00
A0
0F
Total
Trans
02
00
DLE
10
ETX
03
PLC5 System Address
07
00
0B
86
BCC
C0
The response from this command is:
DLE
10
STX
02
DST
11
SRC
0D
CMD
4F
STS
00
TNS
41
D0
DLE
10
ETX
03
BCC
82
Example: Forcing a Coil
Forcing a single coil to either ON or OFF. Refer to the table below for each coil supported
by the UCM-DF1 interface. An integer value of one or greater forces the coil to be ON. An
integer value of zero forces the coil to be OFF.
CMC Data Table
Address (decimal)
220
221
222
223
224
225
CMC Data Table
Address (hex)
DC
DD
DE
DF
E0
E1
Coil Name
(Write only)
Remote Acknowledge
Remote Reset
Remote Load
Remote Unload
Remote Start
Remote Stop
NOTE
For the CMC, forcing the above listed coils OFF is not meaningful because the
default state of each of the above coils is OFF. When using these commands, they
should be sent once (momentary) and the CMC will execute the commands.
NOTE
The Forcing Coil command will override the CMC’s current state. The forced state will
remain valid until the CMC next solves the coil. The coil will remain forced if it is not
programmed in the controller's logic.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
132
CMC TECHNICAL REFERENCE MANUAL
CAUTION
For all of the Remote Coils, the compressor’s REMOTE COMMUNICATIONS
DISABLED/ENABLED selector switch must be in the ENABLED position for these
commands to execute. When DISABLED, the CMC ignores these coils being forced
ON. The REMOTE COMMUNICATIONS DISABLED/ENABLED selector switch is
typically located on the front door of the Compressor’s Control Panel.
To remotely acknowledge the compressor’s alarm or trip condition, the following command
is issued:
DLE
STX
DST
SRC
CMD
STS
10
02
0D
11
0F
00
TNS
E1
FNC
F8
67
A
99
09
Packet
Offset
00
00
B
03
42
01
Total
Trans
01
00
DLE
10
ETX
03
BCC
BC
TNS
E1
F8
DLE
10
ETX
03
00
PLC5 System Address
07
00
0B
DC
The response from this command is:
DLE
10
STX
02
DST
11
SRC
0D
CMD
4F
STS
00
BCC
BA
The following command works the same:
DLE
STX
DST
SRC
CMD
STS
10
02
0D
11
0F
00
TNS
41
FNC
E3
67
A
99
09
Packet
Offset
00
00
B
05
42
01
00
00
00
Total
Trans
02
00
DLE
10
ETX
03
PLC5 System Address
07
00
0B
DC
BCC
6E
The response from this command is:
DLE
10
STX
02
DST
11
SRC
0D
CMD
4F
STS
00
TNS
41
E3
DLE
10
ETX
03
BCC
6F
Example: Forcing Multiple Coils
Forces each coil in a series of contiguous coils to either ON or OFF. Refer to the data table
above for a coil list supported by the UCM-DF1 Interface.
NOTE
The Forcing Multiple Coils command will override the CMC’s current state. The forced
state will remain valid until the CMC next solves the coil. The coil will remain forced if
it is not programmed in the controller's logic.
To force a reset (CMC data table address, DDh) and start (CMC data table address, E0h)
of the compressor the following command is sent:
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
133
CMC TECHNICAL REFERENCE MANUAL
DLE
STX
DST
SRC
CMD
STS
10
02
0D
11
0F
00
TNS
21
FNC
0C
Packet
Offset
00
00
67
A
99
09
11
42
01
00
00
00
01
00
00
Total
Trans
08
00
B
01
00
PLC5 System Address
07
00
00
00
00
DLE
10
ETX
03
BCC
66
0B
01
DD
00
00
00
DLE ETX
10
03
The response from this command is:
DLE
10
STX
02
DST
11
SRC
0D
CMD
4F
STS
00
TNS
21
0C
The number of contiguous coils is four (DD, DE, DF, and E0h). The message length of
integer elements is 8 and the number of data bytes in field B is 16.
Command 0F/Function A2 - SLC Typed Logical Read
The CMC is treated as an SLC5/04 when this command is issued. This function reads a
block of data from CMC starting at a specified data table address.
Example: Reading an Analog Value
To read the pressure setpoint (CMC data table address 86h) as a floating point number, the
following command is issued:
DLE
STX
DST
10
02
0D
SRC CMD STS
0B
0F
00
TNS
D4
19
FNC Byte
Size
A2
04
File
No.
0B
File
Type
8A
Ele
No.
86
S/Ele
No.
00
DLE ETX
10
03
BCC
2B
The response from this command is:
DLE
10
STX
02
DST
0B
SRC
0D
CMD
4F
STS
00
TNS
D4
19
CD
CC
Data
D2
42
DLE
10
ETX
03
BCC
FF
The important command bytes are explained below:
Field
Byte Size
File Number
Description
The number of data bytes to be read.
Address files 0-255 only. For CMC, file 10 is designated for discrete
only. File (11+N) is for the (N+1) th 256 entries in the CMC data table.
85h: bit
89h: integer
8Ah: float
Address elements 0-255 only. The address byte format is the same as
PLC5 for CMC.
254: (FE)
255: (FF-FF-00)
Not used, always 00h.
File Type
Element Number
Sub-Element Number
The four bytes in data field of the response message are converted to a floating point
number, 105.4 PSIG.
To read the pressure setpoint value as integer, the following command is sent:
DLE
STX
DST
10
02
0D
SRC CMD STS
0B
0F
00
TNS
D4
The response from this command is:
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
27
FNC Byte
Size
A2
04
File
No.
0B
File
Type
89
Ele
No.
86
S/Ele
No.
00
DLE ETX
10
03
BCC
1E
BCC
4F
134
CMC TECHNICAL REFERENCE MANUAL
DLE
10
STX
02
DST
0B
SRC
0D
CMD
4F
STS
00
TNS
D4
27
69
00
Data
A0
DLE
10
0F
ETX
03
BCC
86
The first two bytes in data field represent the integer portion, 106 (00-69h), of the setpoint.
The second two bytes represent the fraction portion, 4000 (0F-A0h), of the setpoint.
Example: Reading Multiple Analog Values
The following command reads analog inputs channels 3-9 as integer:
DLE
STX
DST
10
02
0D
SRC CMD STS
0B
00
0F
TNS
D5
A9
FNC Byte
Size
1C
A2
File File
No. Type
0B
89
Ele
No.
03
21
00
0A
S/Ele
No.
00
DLE ETX
10
03
BCC
06
The response from this command is:
DLE
10
STX
02
DST
0B
SRC
0D
CMD
4F
STS
00
00
00
TNS
D5
A9
FF
63
0B
00
5C
Data
00
66
2E
14
09
BC
00
0F
83
Data
20
00
DLE
10
1E
D6
ETX
03
00
62
00
E7
0B
BCC
C0
Example: Reading Single Discrete Data
After reviewing the Electrical Schematic for your compressor, you determine that the digital
input for emergency stop push button is located on J4-P5 (Channel 4). The CMC data table
address is ADh for the input in question. Therefore, to read the state of the emergency stop
push button as a two byte integer, the following command is issued:
DLE
STX
DST
10
02
0D
SRC CMD STS
0B
0F
00
TNS
D6
79
FNC Byte
Size
02
A2
File File
No. Type
0B
89
TNS
D6
79
Data
01
00
Ele
No.
AD
S/Ele
No.
00
DLE ETX
10
03
BCC
A5
The response from this command is:
DLE
10
STX
02
DST
0B
SRC
0D
CMD
4F
STS
00
DLE
10
ETX
03
BCC
49
The data response (01) means that the input is ON, or the emergency stop push button is
pressed.
Example: Reading 16 Bit-Packed Discrete Data
To read 16 bit-packed discrete values for digital outputs as a two-byte integer, the following
command is sent:
DLE
STX
DST
10
02
0D
SRC CMD STS
0B
0F
00
TNS
E1
41
FNC Byte
Size
02
A2
File File
No. Type
0A
85
Ele
No.
0B
S/Ele
No.
00
DLE ETX
10
03
BCC
79
Note that the file number must be 10. The local data file used to store the returned data can
be either bit (85h) or integer (89h) type. The response from this command is:
DLE
10
STX
02
DST
0B
SRC
0D
CMD
4F
STS
00
TNS
E1
41
28
Data
10
10
DLE
10
ETX
03
BCC
3F
Please refer to the PLC5 Typed Read command section for the method to interpret the 16bit discrete values.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
135
CMC TECHNICAL REFERENCE MANUAL
Command 0F/Function AA - SLC Typed Logical Write
The CMC is treated as a SLC5/04 when this command is issued. This command writes a
block of data to CMC starting at a specified data table address. You can write to a setpoint
with either an integer or floating point number.
Example: Presetting Analog Setpoint for 32-bit Value
To write 105.4 PSIG as a floating point number to the user pressure setpoint (CMC data
table address, 86h), issue the following command:
DLE
STX
DST
10
02
0D
SRC CMD STS
0B
0F
TNS
00
E1
FNC Byte
Size
04
AA
70
File File
No. Type
0B
8A
Ele
No.
86
S/Ele
No.
00
Data
CD
CC
D2
DLE
42
10
ETX BCC
03
12
The response from this command is:
DLE
10
STX
02
DST
0B
SRC
0D
CMD
4F
STS
00
TNS
E1
70
DLE
10
ETX
03
BCC
48
Example: Presetting a 16-bit Integer and 16-bit Fraction Analog Setpoint
To change the integer and fraction value for the user pressure setpoint to 105.4 PSIG,
issue the command below. The integer portion of the number 105 (00-69h) and the fraction
0.4 is converted to 4000 (0F-A0h). These four bytes are placed in field B in the order of (6900-A0-0Fh).
DLE
STX
DST
10
02
0D
SRC CMD STS
0B
0F
TNS
00
E1
FNC Byte
Size
04
AA
82
File File
No. Type
0B
89
Ele
No.
86
S/Ele
No.
00
Data
69
00
A0
DLE
0F
10
ETX BCC
03
96
The response from this command is:
DLE
10
STX
02
DST
0B
SRC
0D
CMD
4F
STS
00
TNS
E1
82
DLE
10
ETX
03
BCC
36
Example: Forcing a Coil
Forces a single coil to either ON or OFF. Refer to the CMC data table for each coil
supported by the UCM-DF1 interface. See the same example in the PLC5 Typed Write
command section for more details.
To remotely acknowledge the compressor’s alarm or trip condition, the following command
is issued:
DLE
STX
DST
10
02
0D
SRC CMD STS
0B
0F
00
TNS
E1
FNC Byte
Size
AA
04
A3
File
No.
0B
File
Type
89
Ele
No.
DC
S/Ele
No.
00
Data
01
00
00
DLE
00
10
ETX BCC
03
36
The response from this command is:
DLE
10
STX
02
DST
0B
SRC
0D
CMD
4F
STS
00
TNS
E1
A3
DLE
10
ETX
03
BCC
15
To remotely acknowledge the compressor’s alarm or trip condition, the following command
works the same:
DLE
STX
DST
10
02
0D
SRC CMD STS
0B
0F
00
TNS
E1
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
AD
FNC Byte
Size
AA
02
File
No.
0B
File
Type
89
Ele
No.
DC
S/Ele
No.
00
Data
01
00
DLE
10
ETX BCC
03
2E
136
CMC TECHNICAL REFERENCE MANUAL
The response from this command is:
DLE
10
STX
02
DST
0B
SRC
0D
CMD
4F
STS
00
TNS
E1
AD
DLE
10
ETX
03
BCC
0B
Example: Forcing Multiple Coils
Forces each coil in a series of contiguous coils to either ON or OFF. Refer to the CMC data
table for a list of coils supported by the UCM-DF1 interface. To force a reset (CMC data
table address, DDh) and start (E0h) of the compressor, the following command is sent:
DLE
STX
DST
10
02
0D
SRC CMD STS
0B
0F
00
TNS
E2
FNC
3A
AA
Byte
Size
10 10
File
No.
0B
File
Type
89
Ele
No.
DD
Data
01
00
00
00
01
00
00
00
S/Ele
No.
00
DLE
10
ETX
03
Data
01
00
00
00
01
00
00
00
BCC
8E
NOTE
The byte size value 10h is transmitted as 10h 10h to be distinguished from the control
character DLE.
The response from this command is:
DLE
10
STX
02
DST
0B
SRC
0D
CMD
4F
STS
00
TNS
E2
3A
DLE
10
ETX
03
BCC
7D
The number of contiguous coils is four (DD, DE, DF, and E0h). The assigned local
message buffer length is 8 integer elements, which is 16-byte long.
Allen-Bradley SLC 504 Example
Data Files
RSLogix 500 Ladder Diagram
The following ladder logic example is the fastest and most reliable method for gathering
data from a CMC.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
137
CMC TECHNICAL REFERENCE MANUAL
First Pass
S2:1
N7:0
U
15
0000
15
MSG
Read/Write Message
Peer-To-Peer
Type
Read
Read/Write
500CPU
Target Device
Local
Local/Remote
N7:0
Control Block
14
Control Block Length
Setup Screen
0001
N7:0
N7:0
12
10
EN
DN
ER
N7:0
U
15
0002
MSG
Read/Write Message
Peer-To-Peer
Type
Read
Read/Write
500CPU
Target Device
Local
Local/Remote
N7:20
Control Block
14
Control Block Length
Setup Screen
N7:0
0003
13
N7:20
N7:20
12
10
N7:20
N7:0
N7:20
13
13
10
EN
DN
ER
N7:20
U
15
0004
N7:0
U
15
0005
0006
END
UCM STS Error Codes
STS Code
(hex)
00
10
30
3F
D0
E0
Definition
Success - no error
Illegal command or function
Remote node host is missing, disconnected, or shutdown
Illegal CMC data address or count
Illegal data type
Cannot form CMC data table query/set list
NOTE
The UCM-DF1 driver does not support EXT STS. According to Allen-Bradley DF1
protocol convention, EXT STS is part of the message only if STS = F0h.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
138
CMC TECHNICAL REFERENCE MANUAL
When the CMC receives a DF1 command without any communication error and the
command is executed successfully, a normal response with status code 00h is returned.
If the UCM does not receive the command due to a communication error, no response is
returned and the command initiator will eventually time out.
If the UCM does receive the command, but detects error (invalid BCC/CRC...), control
characters DLE NAK is returned to the command initiator, which in turns retransmits the
command message and restarts a time out to wait for the response. This can be repeated a
few times depending on the limit preset for retransmission. Once the limit is exceeded, the
command initiator is informed of the failure and proceeds to the next command.
If the time out expired before a response is received, the command initiator sends out DLE
ENQ control characters to request a retransmission of the last response. It restarts a time
out and wait for the response. There is a limit on the number of inquiries allowed per
command message. When this limit is exceeded, the command initiator proceeds to the
next command.
When UCM receives DLE ENQ or DLE NAK message, it resends the last response to the
command initiator. When DLE ACK message is received by the UCM, no response is
returned.
When the UCM receives a command without any communication error, but cannot handle
it, the UCM will return an exception response with the appropriate status code informing the
command initiator of the nature of failure.
NOTE
The table below explains the meanings of different control symbols for DF1 protocol:
Control Symbol
DLE ACK
DLE NAK
DLE ENQ
Definition
a message frame has been successfully received
a message frame was not received successfully
request retransmission of a response from the destination node
Communication Parameters
Configuration of the UCM RS-422 port’s communication speed (baud rate), parity, number
of data bits, number of stop bits... is available through the Ingersoll-Rand Service Tool for
the UCM and will be configured by a certified Ingersoll-Rand Service Representative. The
settings should be the same as the 1770-KF2 interface module.
Network Setup
The network diagram that follows depicts the communication interface between AllenBradley DF1 network and Ingersoll-Rand CMC Microcontroller.
The 1770-KF2 always acts as a slave. The slave cannot initiate a command; i.e., the UCM
cannot initiate a command over DH+ network. It only returns response messages to queries
that are addressed to them individually. Broadcast is not supported over the DF1 network.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
139
CMC TECHNICAL REFERENCE MANUAL
CMC Panel
CENTAC  Microcontroller
RS-232 Network for
Operator User Interface,
Twisted Pair Wires with
Common (3 Wires)
IRBUS (RS-485) Network
for Base Control Modules
and Universal
Communication Modules,
Twisted Pair Wires with
Ground (3 Wires)
Base
Control
Module
(BCM)
IRBUS
Address: 1
Serial Port
(COM1)
INGERSOLL-RAND
Service Tool
470
ohm
IRBUS IN
(For IR Use)
IRBUS OUT
(For IR Use)
Base
Control
Module
(BCM)
Service Tool
Plug on
Panel Door
Universal
Communication
Module (UCM)
IRBUS
Address 4
Network Card
Comm Port on
Server
IRBUS
Address: 2
INGERSOLL-RAND
Air System Controller
(ASC)
Universal
Comm.
Module
(UCM)
IRBUS
Address 5
Universal
Comm.
Module
(UCM)
IRBUS
Address 6
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Next CMC Panel(s) for
use in ASC
Modbus Network #1
Full or Half Duplex
RS-422 or RS-485
DF1 Network
Full Duplex RS-422A
Cat5
Cable
Ethernet to
Modbus
Bridge
To DH+
Network
Allen-Bradley
1770-KF2
Interface Module
140
CMC TECHNICAL REFERENCE MANUAL
1770-KF2 Setup
A 1770-KF2 module links asynchronous devices (RS-422A or RS-232C) to an AllenBradley Data Highway or Data Highway Plus network. The 1770-KF2 module has 8 switch
assemblies that let you select various communication options. The switch assemblies are
shown in the diagram below:
Switch Assembly
SW-1
SW-2, SW-3, SW-4
SW-5
SW-6
SW-7
SW-8
Communication Option
Asynchronous link features
Node number
Network link communication rate
Asynchronous link communication rate
DH/DH+ network link section
RS-232C/RS-422A selection
CAUTION
The 1770-KF2 module reads the status of these communication option
switches only at power up, so you need to change switch settings with 1770-KF2
powered off.
SW-1 (Asynchronous Link Features)
The following table shows the different combinations available for setting the asynchronous
link with the 5 dipswitches of SW-1.
Protocol
Error
Check
Parity
Embedded
Response
1
2
Full Duplex
Full Duplex
Full Duplex
Full Duplex
Full Duplex
BCC
BCC
BCC
BCC
CRC
None
Even
None
Even
None
No
No
Yes
Yes
Yes
OFF
ON
OFF
ON
OFF
OFF
OFF
ON
ON
ON
SW-1 Settings
3
(Duplicate
Message)
ON: ignore
OFF: accept
OFF
OFF
OFF
OFF
OFF
4
(Hand
Shake)
5
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
CAUTION
Only the UCM-DF1 driver supports the full duplex options. Half duplex is not
supported.
SW-2, SW-3, SW-4 (Node Address)
These three switch assemblies are used to set the network node number of the 1770-KF2
module. Set both switches in SW-2 OFF for DH+ link because the node number should be
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
141
CMC TECHNICAL REFERENCE MANUAL
a 2-digit octal number that identifies the 1770-KF2 as a unique node on DH+. Valid node
numbers for 1770-KF2 in DH+ network are 00 to 77 octal.
First digit (SW-2) should always be set to zero.
SW-2 Setting
1
2
OFF
OFF
OFF
ON
ON
OFF
ON
ON
Digit
0
1
2
3
Second and third digits:
1
OFF
OFF
OFF
OFF
ON
ON
ON
ON
SW-3, SW-4 Setting
2
OFF
OFF
ON
ON
OFF
OFF
ON
ON
3
OFF
ON
OFF
ON
OFF
ON
OFF
ON
Digit
0
1
2
3
4
5
6
7
SW-5 (Network Link Communication Rate)
Switch assembly SW-5 lets you select the communication rate for the 1770-KF2 module’s
network link (DH+). Set both switches ON for a network communication rate of 57,600 bits
per second. Be sure to set all modules on the same DH+ network for this communication
rate.
SW-6 (Asynchronous Link Communication Rate and Diagnostic Commands)
Switches #1, #2, #3 of SW-6 let you select the communication rate for the 1770-KF2
module’s asynchronous port. Meanwhile, switch #4 determines how 1770-KF2 module
treats diagnostic commands sent by a remote DH+ node. It is recommended to set at 9600
baud or higher, and execute received diagnostic commands.
Execute received diagnostic commands
Pass any received diagnostic commands to the attached asynchronous device
SW-6 Setting
4
ON
OFF
The available baud rate settings are shown below:
Baud Rate
(Bits per second)
110
300
600
1200
2400
4800
9600
19200
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
1
OFF
ON
OFF
ON
OFF
ON
OFF
ON
SW-6 Setting
2
OFF
OFF
ON
ON
OFF
OFF
ON
ON
3
OFF
OFF
OFF
OFF
ON
ON
ON
ON
142
CMC TECHNICAL REFERENCE MANUAL
SW-7 (Network Link Selection)
UCM only supports DH+ network. SW-7 should always select DH+.
Network
Mode
DH
DH+
SW-7 Setting
1
2
OFF
OFF
ON
OFF
SW-8 (RS-232C/RS-422A Selection)
The UCM-DF1 interface uses RS-422 communication. SW-8 should select RS422.
Communication
Type
RS-232C
RS-422A
SW-8 Setting
1
2
OFF
ON
ON
OFF
Wiring Diagram for RS-422A
1770 KF2
Module
RS-422
1
14
25
16
18
UCM
RS-422
GND
TX+
TXRX+
RX-
Cable not to exceed 4000 feet
RX+
RXTX+
TX-
4
5
6
8
20
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
143
Documentation
An Electrical Schematic drawing is provided as standard after order placement. Control Panel
Outline drawings are optional. Logic diagrams are considered proprietary and are not available.
System Information
Status Codes
The following table lists the status codes for the Base Control Module (BCM) only. These
codes indicate every operating condition, both normal and abnormal, for the system. A code
always exists for the system; for example, Status 05h indicates that the system is running
properly.
These codes, except Status 00h and 05h, are shown on a blank screen in the upper left
hand corner of the Operator User Interface (OUI). Since Status 00h and 05h are normal
operating conditions, these codes are not displayed. When a code is displayed, contact
your local Ingersoll-Rand Service Representative.
Status
Code
00h
Definition
Booting
01h
Stay In Boot
02h
ROM CRC Failed
03h
Commanded To Boot
04h
Invalid Application
05h
06h
Application Running
Fatal Exit
07h
System Error
08h
Incompatible Software
Versions
A-D System Error
D-A System Error
Digital I/O System Error
Logic Engine System or
Loop Task Error
Comparator System Error
Operator User Interface
Error
09h
0Ah
0Bh
0Ch
0Dh
0Eh
0Fh
Data Logging System Error
10h
Low Power
Comments
The BCM is in the boot process. This is a normal process during BCM power up.
This state will not be displayed.
The BCM is held in boot mode by the hardware configuration. This condition exists
only when the boot jumper (hardware device) is plugged into the display (OUI) port.
This hardware jumper is only required when doing system level reprogramming of
the module.
The BCM software is not valid. This condition occurs when the CRC (Cyclic
Redundancy Check) calculated by the module does not equal the CRC value written
to the module when programmed. This would typically occur when the programming
process is aborted (halted). The module must be reprogrammed.
The BCM is currently in the process of being programmed. If this message does not
disappear after programming is completed, power cycle the unit.
The BCM software has failed to operate properly. Cycling the power on the module
will restart the system. Once restarted, the program will operate properly until the
same condition reoccurs.
Normal operating condition. This state will not be displayed.
Operating system error. Cycling the power on the module will restart the system.
Once restarted, the program will operate properly until the same condition reoccurs.
Operating system error. Cycling the power on the module will restart the system.
Once restarted, the program will operate properly until the same condition reoccurs.
The BCM application software and tables are not compatible. The module must be
reprogrammed.
Analog input system error. A hardware malfunction has occurred.
Analog output system error. A hardware malfunction has occurred.
Digital input and output system error. A hardware malfunction has occurred.
Ladder logic processing system or loop task error. The module must be
reprogrammed.
Comparator system error. The module must be reprogrammed.
Operator User Interface system error. Cycling the power on the module will restart
the system. Once restarted, the program will operate properly until the same
condition reoccurs.
Data logging system error. Cycling the power on the module will restart the system.
Once restarted, the program will operate properly until the same condition reoccurs.
Power supply voltage (+24 VDC) dropped below minimum operating level. Check
power supply. Cycle power when voltage is within proper operating limits. Once
restarted, the program will operate properly until the same condition reoccurs.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
144
CMC TECHNICAL REFERENCE MANUAL
Status
Code
11h
Definition
Task Overrun
12h
Watchdog Failure
13h
Intermodule Data Error
14h
Calculation Block Error
15h
Interpolation System Error
16h
Calibration System Error
Comments
System processing capabilities do not meet requirements for operation. Cycling the
power on the module will restart the system. Once restarted, the program will
operate properly until the same condition reoccurs.
The internal backup system monitor is not operational. BCM hardware should be
replaced. Cycling the power on the module will restart the system. Once restarted,
the program will operate properly until the same condition reoccurs.
An error has occurred while generating a message to be sent from one BCM to the
other BCM in a multi-module configuration. The module must be reprogrammed.
A stack underflow or overflow has occurred in a calculation block. The module must
be reprogrammed.
An error has occurred in the interpolation block. The module must be
reprogrammed.
Occurs during initialization of the EEPROM block. The module must be
reprogrammed.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
145
CMC TECHNICAL REFERENCE MANUAL
Base Control Module (BCM)
Module Layout
J15-Digital Outputs, Channels 4-1
J14-Digital Outputs, Channels 8-5
J13-Digital Outputs, Channels 12-9
J12-Digital Outputs, Channels 16-13
Pin 1
J10-Power Input
(24 VDC)
Pin 1
Pin 1
F102-Fuse for AnalogI/O
(J1, J2 and J3)
Pin 1
J9-Current Transformer
Input (0-5 Amps)
Pin 1
F101-Fuse for Operator
User Interface (Display)
F103-Fuse for Digital
Inputs (J4 and J5)
F100-Fuse for Base
Module CPU Card
J8-Speed Sensor
Input (1-150 Hz)
Pin 1
J7-RS485 Serial
Data Link (IRBUS)
Pin 4
All Fuses are 5x20mm, GMA
1.5 amp, Fast Blow
J7-RS232 Serial
Data Link (Display),
Pin 1
J6-RS232 Serial
Data Link (Display),
Female DB9
J5-Digital (Discrete)
Inputs (24 VDC),
Channels 9-16
Pin 1
J4-Digital (Discrete)
Inputs (24 VDC),
Channels 1-8
Pin 1
J3-Analog Outputs
(4-20mA)
Channels 1-4
Pin 25
Pin 7
Pin 1
Pin 5
Pin 1
Pin 1
J1-Grounded Analog Inputs,
(4-20mA) Channels 3-23
J2-Floating Analog Inputs, (4-20mA) Channels 1-2
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
146
CMC TECHNICAL REFERENCE MANUAL
Connector Description
Tag
Type
Channel
Module Connector
Mating Connector
J1
Grounded Analog Inputs, 4-20 mA
3-23
(2) Phoenix MDST
2, 5/24-3T-5, 08
J2
Floating Analog Inputs, 4-20 mA
1-2
J3
Analog Outputs, 4-20 mA
1-4
J4
J5
J6
Digital (Discrete) Inputs, 24 VDC
1-8
9-16
na
(12) Phoenix
MDSTB 2, 5/2-G-5,
08
(2) Phoenix MDSTB
2, 5/2-G-5, 08
(3) Phoenix MDSTB
2, 5/2-G-5, 08
Phoenix MSTBA 2,
5/10-G-5, 08
9 Position “D” Sub
Miniature (Female)
Phoenix MSTBA 2,
5/9-G-5, 08
Phoenix MSTBA 2,
5/3-G-5, 08
Terminal Strip
Phoenix MSTBA2,
5/5-G-5, 08
(4) Phoenix MSTBA
2, 5/8-G-5, 08
J7
J8
J9
J10
J12
J13
J14
J15
RS232 Serial Data Link (Operator
User Interface)
RS232 Serial Data Link (OUI)
RS485 (IRBUS) Serial Data Link
Speed Sensor Input, Variable
Reluctance
Current Transformer Input
Power
Digital Outputs
na
na
na
13-16
9-12
5-8
1-4
(2) Phoenix MDST
2, 5/4-3T-5, 08
(2) Phoenix MDST
2, 5/6-3T-5, 08
Phoenix MSTB 2,
5/10-ST-5, 08
9 Position “D” Sub
Miniature (Male)
Phoenix MSTB 2,
5/5-ST-5, 08
Phoenix MSTB 2,
5/3-ST-5, 08
Wire Lugs
Phoenix MSTB 2,
5/5-ST-5, 08
(4) Phoenix MSTB
2, 5/8-ST-5, 08
NOTES:
1. BCM Weight: 1775 ± 177g [3.92 ± .39 lb.]
2. BCM Size: Length=355.6 mm [14.0 in] x Width=247 mm [9.7 in] x Depth=45 mm [1.8 in]
3. To ensure chassis ground, install 12-gauge ground strap between this module and the
NEMA enclosure. Place external tooth lock washer between this module and the ground
strap.
4. “na” is defined as “not applicable”.
5. All Phoenix connectors may be replaced with an equal supplier.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
147
CMC TECHNICAL REFERENCE MANUAL
Connector Input and Output (I/O)
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
J1-Grounded Analog Inputs
Analog Input Channel 3
Power 24 VDC, Channels 3 & 4
Shield, Channels 3 & 4
Analog Input Channel 4
Analog Input Channel 5
Power 24 VDC, Channels 5 & 6
Shield, Channels 5 & 6
Analog Input Channel 6
Analog Input Channel 7
Power 24 VDC, Channels 7 & 8
Shield, Channels 7 & 8
Analog Input Channel 8
Analog Input Channel 9
Power 24 VDC, Channels 9 & 10
Shield, Channels 9 & 10
Analog Input Channel 10
Analog Input Channel 11
Power 24 VDC, Channels 11 & 12
Shield, Channels 11 & 12
Analog Input Channel 12
Analog Input Channel 13
Power 24 VDC, Channels 13 & 14
Shield, Channels 13 & 14
Analog Input Channel 14
Analog Input Channel 15
Power 24 VDC, Channels 15 & 16
Shield, Channels 15 & 16
Analog Input Channel 16
Analog Input Channel 17
Power 24 VDC, Channels 17 & 18
Shield, Channels 17 & 18
Analog Input Channel 18
Analog Input Channel 19
Power 24 VDC, Channels 19 & 20
Shield, Channels 19 & 20
Analog Input Channel 20
Analog Input Channel 21
Power 24 VDC, Channels 21 & 22
Shield, Channels 21 & 22
Analog Input Channel 22
Analog Input Channel 23
Power 24 VDC, Channel 23
Shield, Channel 23
Spare
Spare
Power 24 VDC, Spare
Shield, Spare
Spare
Pin
1
2
3
4
5
6
7
8
J2-Floating Analog Inputs
Analog Input Channel 1+
Power 24 VDC, Channel 1
Analog Input Channel 1Shield, Channel 1
Analog Input Channel 2+
Power 24 VDC, Channel 2
Analog Input Channel 2Shield, Channel 2
Pin
1
2
3
4
5
6
7
8
9
10
11
12
J3-Analog Outputs
Analog Output Channel 1+
Power 24 VDC, Channels 1 & 2
Analog Output Channel 1Analog Output Channel 2+
Shields, Channels 1 & 2
Analog Output Channel 2Analog Output Channel 3+
Power 24 VDC, Channels 3 & 4
Analog Output Channel 3Analog Output Channel 4+
Shields, Channels 3 & 4
Analog Output Channel 4-
Pin
1
2
3
4
5
6
7
8
9
10
J4-Digital Inputs
Power 24 VDC, Channels 1-8
Digital Input Channel 1
Digital Input Channel 2
Digital Input Channel 3
Digital Input Channel 4
Digital Input Channel 5
Digital Input Channel 6
Digital Input Channel 7
Digital Input Channel 8
Ground, Channels 1-8
Pin
1
2
3
4
5
6
7
8
9
10
J5-Digital Inputs
Power 24 VDC, Channels 9-16
Digital Input Channel 9
Digital Input Channel 10
Digital Input Channel 11
Digital Input Channel 12
Digital Input Channel 13
Digital Input Channel 14
Digital Input Channel 15
Digital Input Channel 16
Ground, Channels 9-16
Pin
1
2
3
4
5
6
7
8
9
J6-RS232 (Display)
Not Used
Receive Data (RxD)
Transmit Data (TxD)
Not Used
Signal Ground
Not Used
Not Used
Not Used
Not Used
Pin
1
2
3
4
5
6
7
8
9
J7-RS232 (Display) / RS485 (IRBUS)
Receive Data (RxD)
(Display)
Transmit Data (TxD)
(Display)
Signal Ground
(Display)
Data Link 1+
(IRBUS)
Data Link 1(IRBUS)
Data Link Ground (IRBUS)
Data Link 1+
(IRBUS)
Data Link 1(IRBUS)
Data Link Ground (IRBUS)
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Pin
1
2
3
J8-Speed Sensor
SS+
SSSS Ground
Pin
1
2
J9-Current Transformer
CT+
CT-
Pin
1
2
3
4
5
J10-Power
Power +24V DC
Power Ground
Chassis Ground
Display Power +24VDC
Display Power Ground
Pin
1
2
3
4
5
6
7
8
J12-Digital Outputs
Digital Output Channel 16
Digital Output Channel 16
Digital Output Channel 15
Digital Output Channel 15
Digital Output Channel 14
Digital Output Channel 14
Digital Output Channel 13
Digital Output Channel 13
Pin
1
2
3
4
5
6
7
8
J13-Digital Outputs
Digital Output Channel 12
Digital Output Channel 12
Digital Output Channel 11
Digital Output Channel 11
Digital Output Channel 10
Digital Output Channel 10
Digital Output Channel 9
Digital Output Channel 9
Pin
1
2
3
4
5
6
7
8
J14-Digital Outputs
Digital Output Channel 8
Digital Output Channel 8
Digital Output Channel 7
Digital Output Channel 7
Digital Output Channel 6
Digital Output Channel 6
Digital Output Channel 5
Digital Output Channel 5
Pin
1
2
3
4
5
6
7
8
J15-Digital Outputs
Digital Output Channel 4
Digital Output Channel 4
Digital Output Channel 3
Digital Output Channel 3
Digital Output Channel 2
Digital Output Channel 2
Digital Output Channel 1
Digital Output Channel 1
148
CMC TECHNICAL REFERENCE MANUAL
Operator User Interface Module (OUI)
Module Layout
Side View
J1-RS232 Port
Pin 1
J3-RS232 Port
Pin 1
Pin 1
J2-Input Power
Connector Description
Tag
Type
J1
RS232 Port
J2
Input Power
J3
RS232 Port
Module Connector
Mating Connector
9 Position “D” Sub
Miniature (Female)
Phoenix MSTBA2,
5/2-G-5, 08
Phoenix MC 1.5/5G-3.81
9 Position “D” Sub
Miniature (Male)
Phoenix MSTW2,
5/2-ST-5, 08
Phoenix MC 1.5/5ST-3.81
NOTES:
1. OUI Weight: 410 g [0.90 lb.]
2. OUI Size: Length=267 mm [10.5 in] x Width=175 mm [6.9 in] x Depth=60 mm [2.4 in]
3. All Phoenix connectors may be replaced with an equal supplier.
Connector Input and Output (I/O)
Pin
1
J1-RS232 Port
No Connection
Pin
1
2
3
4
5
6
7
8
9
Transmit (TX)
Receive (RX)
No Connection
Signal Common
No Connection
No Connection
No Connection
No Connection
2
J2-Input Power
+12 To +24 VDC
(VPOWER)
Ground (GND)
Pin
1
J3-RS232 Port
RS232 Data Link Tx
2
3
4
5
RS232 Data Link Rx
Common (Com)
IRBUS RS485 Data Link (DL+)
IRBUS RS485 Data Link (DL-)
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
149
CMC TECHNICAL REFERENCE MANUAL
OUI PCB Assembly (Cover Removed)
Showing replaceable fuse
J1
9 Position
"D" Sub
Connector
Fast-Acting, SMF, .75A, 125V
Littlefuse 0451.750 or 0453.750
or Equivalent
J3
5 Pin
Connector
F2
J2
2 Pin
Connector
CMC User Interface/Bezel Cleaning Instructions
The following procedure is recommended to clean the CMC User Interface vinyl overlay
material and/or the User Interface bezel.
1. Stop the compressor and depress the maintained ‘Emergency Stop’ push-button, this
will prevent an inadvertent start up or trip of the compressor during the cleaning
process.
2. Dampen a soft cloth or paper towel with water and wipe any dust, dirt or liquids from the
surface of the User Interface, do not use an abrasive pad or brush to clean the surface
of the User Interface vinyl overlay or bezel.
3. If more aggressive measures are required to clean the User Interface and/or bezel
surface use a mild non-abrasive household cleaner (such as Formula 409, Fantastik,
etc.) sprayed or wiped directly onto the surface to be cleaned. Dampen a soft cloth or
paper towel with water and wipe any remaining cleaner from the surfaces.
Ingersoll-Rand Company recommends the following for cleaning the OUI and bezel:
Cleaners: Water or mild household cleaner, no petroleum or acetone based fluids.
Cleaning wipes: Soft cotton clothe or paper towels.
Backlight Replacement Procedure
Tools Needed:
1. Flat blade screwdriver with a small tip (1/8 inch)
2. Number 1 Phillips Screwdriver
3. Electrostatic Discharge Strap Connected to Earth Ground
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
150
CMC TECHNICAL REFERENCE MANUAL
Step 1
J1
User
Terminal
J3
User
Terminal
Tx
Rx
COM
DL+
DL-
Lift cover to remove
J2
Loo
s
+
en
scr
ew
s, s
l
ide
righ
Step 2
Remove
cabling
Unplug connector
and remove nylon
cable retainer screws
Display
Power
t
Step 3
Step 4
Remove screws from the
lower printed circuit
board, then use a
screwdriver to gently pry
the backlight panel loose.
Use circular stand-offs to
rest screwdriver shaft
against while prying
backlight panel out.
The backlight is part of a larger panel
that is removed as an assembly.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
151
CMC TECHNICAL REFERENCE MANUAL
Step 5
Step 6
Backlight panel is
inserted into display
between the circuit board
and the LCD glass with
the white plastic backing
sheet and wires facing
toward the circuit boards.
Slide the backlight panel
in place and align the
screw holes so the screws
may be inserted and
tightened.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Insert screws being careful
not to over tighten.
Route wiring, replace nylon cable retainers,
insert backlight plug, replace main cover
and connect power and communication
cable to complete installation.
152
CMC TECHNICAL REFERENCE MANUAL
Universal Communication Module (UCM) Optional
Module Layout
Side View
J2-Service/Modem
(RS232) Port
J1-Microcontroller/Network
(RS422/RS485) Port
Pin 1
J3-Input Power
Pin 1
Pin 1
Top View
RS232 Activity
Indicator
IRBUS RS485
Activity Indicator
RS422/485 Activity Indicator
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
153
CMC TECHNICAL REFERENCE MANUAL
Connector Description
Tag
Type
Module Connector
Mating Connector
J1
Microcontroller/Network
(RS422/485) Port
Phoenix MSTBA2,
5/8-G-5, 08
Phoenix MSTBW2,
5/24-ST-5, 08
J2
Service/Modem (RS232)
Port
9 Position “D” Sub
Miniature (Female)
9 Position “D” Sub
Miniature (Male)
J3
Input Power
Phoenix MSTBA2,
5/2-G-5, 08
Phoenix MSTW2,
5/2-ST-5, 08
NOTES:
1. UCM Weight: 410 g [0.90 lb.]
2. UCM Size: Length=136 mm [5.4 in] x Width=143 mm [5.6 in] x Depth=31 mm [1.2 in]
3. All Phoenix connectors may be replaced with an equal supplier.
Connector Input and Output (I/O)
Pin
1
2
3
4
5
6
7
8
J1-Microcontroller/Network Port
IRBUS RS485 Datalink + (DL+)
IRBUS RS485 Datalink - (DL-)
Ground (GND)
RS422/485 Transmit + (TX+)
RS422/485 Transmit - (TX-)
RS422/485 Receive + (RX+)
RS422/485 Receive - (RX-)
Ground (GND)
Pin
1
2
3
4
5
6
7
8
9
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
J2-Service/Modem Port
No Connection
Transmit (TX)
Receive (RX)
No Connection
Signal Common
No Connection
No Connection
No Connection
No Connection
Pin
1
2
J3-Input Power
+12 To +24 VDC (VPOWER)
Ground (GND)
154
CMC TECHNICAL REFERENCE MANUAL
UCM Port Activity LEDs
The UCM has three light emitting diodes (LEDs) to indicate the activity of the RS232,
RS422/485 and the IRBUS RS485 ports. The following table indicates the different states of
these ports.
RS232
off
on
RS422
RS485
off
off
IRBUS
RS485
off
off
on
on
blinking
blinking
on
on
on
on
on
blinking
blinking
on
on
on
blinking
blinking
blinking
on
blinking
blinking
blinking
UCM State
No power (24 VDC)
Boot mode, check A1 switch for being non-zero (cycle
power to exit boot mode)
Running, but no communication on any port
Multi-module job with inter-module communication
Service Tool in use
Service Tool in use, but no response from BCM … check
connection between BCM and UCM
MODBUS communication in use
RS-422 port in use, but no response from BCM … check
connection between BCM and UCM or Modbus and DF1
address
All blinking together imply a continuous reboot or application
problem
UCM Communications Parameters
The UCM has three communication ports, RS232, RS422/485 and IRBUS RS485. Each of
these ports has its own communication parameters that it supports.
Service Tool
RS-232
50 feet (15.2 meters)
9600
Modbus/DF1
IRBUS
Parameter
RS-422/485
RS-485
Distance
4000 feet (1218.3 Meters) 100 feet (30.4 Meters)
Baud Rate
300, 600, 1200, 2400,
9600
9600, 19200, 38400
Parity
None
None, Even, Odd
None
Data Bits
8
8
8
Stop Bits
1
1, 1.5, 2
1
Configurable No
Yes*
No
* A certified Ingersoll-Rand Service Representative will provide this configuration.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
155
CMC TECHNICAL REFERENCE MANUAL
RS422/485 Network Wiring Diagram - Full Duplex
SERVER
(Modbus Master)
Compressor Panel #n
Modbus Address - nn
IRBUS Address - any
120 VAC
To Server's
Network Card
Ethernet
Switch
Ethernet
Cable
Cat5 or
Better
Compressor Panel #6
Modbus Address - 06
IRBUS Address - any
Compressor Panel #5
A terminating resistor
is not required at the
end of the network.
Modbus Address - 05
IRBUS Address - any
Rx- Rx+ Tx+ Tx-
Ethernet /
Modbus
Bridge
The maximum
distance of a
MODBUS Network is
4000 electrical feet;
i.e., the length of the
wire from the Ethernet
Bridge (Location A) to
the last compressor's
Universal
Communication
Module (Location B).
The maximum number
of devices (nodes) on
a MODBUS Network is
30.
3 Com
120 VAC
B
Compressor Panel #4
RS-422
2 Twisted Pair Wires
with Ground (5 Wires)
Modbus Address - 04
IRBUS Address - any
174 CEV
300
Compressor Panel #3
24VDC +
Fused -
Modbus Address - 03
IRBUS Address - any
RS-422
2 Twisted
Pair Wires
Plus Gnd.
(5 Wires)
Connect
Ground
One End
Only
To
Power
Supply
24+ Gnd
Power
To
Power
Supply
To
BCM
DL+ DL- Gnd Tx+ Tx- Rx+ Rx- Gnd
RS-485
RS-422/485
RS-232
DB-9
Universal Communication Module (UCM)
Modbus Address - 01
(Set through software)
Compressor Panel #1
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
RS-422
2 Twisted
Pair Wires
with Ground
(5 Wires)
24+ Gnd
Power
To
BCM
DL+ DL- Gnd Tx+ Tx- Rx+ Rx- Gnd
RS-485
RS-422/485
RS-232
DB-9
Universal Communication Module (UCM)
Modbus Address - 02
(Set through software)
Compressor Panel #2
156
CMC TECHNICAL REFERENCE MANUAL
RS422 Network Wiring Diagram - Half Duplex
SERVER
(Modbus Master)
Compressor Panel #n
Modbus Address - nn
IRBUS Address - any
120 VAC
To Server's
Network Card
Ethernet
Switch
Ethernet
Cable
Cat5 or
Better
Compressor Panel #6
The maximum
distance of a
MODBUS Network is
4000 electrical feet;
i.e., the length of the
wire from the Ethernet
Bridge (Location A) to
the last compressor's
Universal
Communication
Module (Location B).
The maximum number
of devices (nodes) on
a MODBUS Network is
30.
3 Com
Modbus Address - 06
IRBUS Address - any
120 VAC
B
Compressor Panel #5
A terminating resistor
is not required at the
end of the network.
Modbus Address - 05
IRBUS Address - any
Rx- Rx+ Tx+ Tx-
Compressor Panel #4
Ethernet /
Modbus
Bridge
RS-422
Twisted Pair Wires
with Ground (3 Wires)
Modbus Address - 04
IRBUS Address - any
174 CEV
300
24VDC +
Fused -
Compressor Panel #3
A
Modbus Address - 03
IRBUS Address - any
RS-422
Twisted Pair
Wires
With Ground
(3 Wires)
Connect
Ground
One End
Only
To
Power
Supply
24+ Gnd
Power
To
BCM
DL+ DL- Gnd Tx+ Tx- Rx+ Rx- Gnd
RS-485
RS-422/485
RS-232
DB-9
Universal Communication Module (UCM)
Modbus Address - 01
(Set through software)
Compressor Panel #1
RS-422
Twisted Pair
Wires with
Ground (3
Wires)
To
Power
Supply
24+ Gnd
Power
To
BCM
DL+ DL- Gnd Tx+ Tx- Rx+ Rx- Gnd
RS-485
RS-422/485
RS-232
DB-9
Universal Communication Module (UCM)
Modbus Address - 02
(Set through software)
Compressor Panel #2
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
157
Terminating Resistor – Modbus Network
The RS422/485 circuitry built into each UCM supports Alternate-Fail-safe AC Termination.
This termination circuitry enhances the UCM's ability to operation in harsher (electrically
noisier) environments. Since this circuitry is built into the product, no external terminating
resistor is required. For a thorough discussion of the various termination techniques, please
refer to "A Comparison of Differential Termination Techniques", National Semiconductor
Application Note 903 (AN-903), August 1993. This application note can be obtained from
the Internet at "www.national.com".
Terminating Resistor – IRBUS Network
Due to the data rate the RS485 IRBUS is provided with termination resistors mounted
inside the panel. The value of each resistor is 470 ohms. The purpose of the termination is
to prevent reflections. Reflections occur when a signal encounters different impedance and
is reflected back towards the source. This can corrupt the intended data transmission.
Where IRBUS is networked with other panels two termination resistors are required, one at
each end of the network.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
158
CMC TECHNICAL REFERENCE MANUAL
Typical System Layout
Operator User Interface (OUI)
CENTAC 
Microcontroller
24 VDC Power
RS232
Base Control Module
(BCM) #1
470
ohm
IRBUS OUT
IRBUS IN
IRBUS (RS485)
IRBUS (RS485)
24 VDC
120/240 VAC
Power
Universal
Communications
Module (UCM)
Base Control Module
(BCM) #2
Power Supply
24 VDC
Service Tool
Port Not Shown
24 VDC
Optional
Equipment
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
159
CMC TECHNICAL REFERENCE MANUAL
Network Diagram
CMC Panel
CENTAC  Microcontroller
RS-232 Network for
Operator User Interface,
Twisted Pair Wires with
Common (3 Wires)
IRBUS (RS-485) Network
for Base Control Modules
and Universal
Communication Modules,
Twisted Pair Wires with
Ground (3 Wires)
Base
Control
Module
(BCM)
IRBUS
Address: 1
Serial Port
(COM1)
INGERSOLL-RAND
Service Tool
470
ohm
IRBUS IN
(For IR Use)
IRBUS OUT
(For IR Use)
Base
Control
Module
(BCM)
Service Tool
Plug on
Panel Door
Universal
Communication
Module (UCM)
IRBUS
Address 4
Network Card
Comm Port on
Server
IRBUS
Address: 2
INGERSOLL-RAND
Air System Controller
(ASC)
Universal
Comm.
Module
(UCM)
IRBUS
Address 5
Universal
Comm.
Module
(UCM)
IRBUS
Address 6
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Next CMC Panel(s) for
use in ASC
Modbus Network #1
Full or Half Duplex
RS-422 or RS-485
Modbus Network #2
Full or Half Duplex
RS-422 or RS-485
Cat5
Cable
Ethernet to
Modbus
Bridge
To next CMC Panel
or any other
Modbus compliant
product
160
CMC TECHNICAL REFERENCE MANUAL
Technical Specification
DESCRIPTION OF STANDARD
Switches, Lights and Push Buttons
Control Power On/Off switch... activates panel power and prelube pump
Compressor trouble light (red)
Emergency stop pushbutton
Microprocessor OUI
240x128 pixel LCD graphic display window
Tabbed folders for ease of navigation
Status Bar with compressor state
Eighteen screens of compressor information and setup data
Left/Right/Up/Down/Return push buttons
Acknowledge/Reset push buttons
Start/Stop push buttons
Load/Unload push buttons
Contrast Button
Event Log
Most recent 224 events with name, time, date and value
Logged events
Alarms
Trips
Command key press (local and remote)
E-Stop pressed
Module control power up and down
MinLoad reset
Analog input failed
Setpoint change (local and remote)
Automatic start and stop (when Auto Hot Start purchased)
Surge Unload
Compressor Started
Driver Failed to Start
Loss of Motor Power
Language and Units of Measure
Language and Units of Measure Sets
Two Language and Units of Measure sets are select-able from the display.
NOTE: The English language and psia, degF, mils are standard for all
units. English and kPA, degC, microns are the default alternate
language unless otherwise specified. Other Units of Measure are
available upon request.
Languages
Arabic
Bulgarian
Chinese
Croatian
Czech
Danish
Dutch
French
Finnish
German
Greek
Hungarian
Italian
Norwegian
Polish
Portuguese
Romanian
Russian
Slovakian
Slovenian
Spanish
Swedish
Turkish
Units of Measure
Available upon request.
Control Functions
Modulate or Autodual
Manual Valve control for compressor setup
High motor load limit (controls maximum opening of inlet valve)
MinLoad (controls minimum opening of inlet valve)
Partial Unload on Surge
Moves inlet valve to minimum load setting and bumps the bypass valve
open to exit the surge condition
Minimizes duration and magnitude of pressure drop from surge
Surge Indexing
Actual/Alarm/Trip Functions
Low oil pressure
High/low oil temperature
High air temperature into last compression stage
High stage shaft vibrations, single plane
Alarm Function
Surge
Trip Function
Low seal air (interlocked w/ prelube pump operation)
PHYSICAL DATA
Panel Construction
NEMA 12 enclosure
Formed and welded 11-gauge carbon steel cabinet, 14 gauge door
Door gasket with butt type hinges
Back panel for component mounting
Dimensions
Panel1
Panel2
Height
54 in (137.2 cm)
54 in (137.2 cm)
Width
32 in (81.3 cm)
35 in (88.9 cm)
Depth
12 in (30.5 cm)
14 in (35.6 cm)
1 - No Starter or size 5 starter panels
2 - with size 5DP or size 6 starter panels
Controller Board
14.0 in (35.5 cm)
9.7 in (24.6 cm)
1.0 in (2.5 cm)
Weight
Without starter 300 lb. (136.1 kg)
With size 5 starter 350 lb. (158.8 kg)
With size 6 starter 375 lb. (170.1 kg)
Component Data
Canadian Standard Association (CSA)
Underwriters Laboratories (UL) approved components
Control Wiring
High voltage and low voltage wiring segregation
TEW wire with PVC insulation (meets NEMA VM-1 for Flame
Retardant
105 degC temperature rise on insulation
600 V rating, 18 gauge for instrumentation and signal, 16 gauge for
control
Heat shrink wire markers for harness
Clip-on wire markers internal to panel
Wire Ferules
Terminal Blocks
300 VAC design for #22 through #10 wire size
Tubular clamp contacts and tang clamping collar, DIN Rail mounted
Push Buttons/Selector Switches/Indicating Lights
Corrosion resistant, Oil-tight
Designed and manufactured to NEMA 4/12/13
Pilot lights are 120 VAC full voltage type
Control Interposing Relays
Two normally open and Two normally closed contacts rated:
1/3HP 10AMP 120VAC
1/2HP 10AMP 240VAC
10AMP 28VDC
Coil rated 120 VAC
Contacts
Normally Open, 5 amps at 120 VAC
Pressure Transducers
Ranges 0-50 PSIG, 0-200 PSIG, 0-500 PSIG, 4-20 mA Output
Channel
7/16-20 SAE or 1/4" NPT pressure port fitting
Hirschmann GSA3000N connection head fitting for machine mounted
model
Temperature Transducers
0-500 degF operating range, 4-20 mA transmitter
100 ohm platinum, TCR=0.00385
Four compression type terminals
NEMA 4 rating
Vibration Transmitters
Eddy current probe
Vibration range 0-4 mils, Frequency range 5-3000 Hz
Output Channel 4-20 mA and 200 mV/Mil, Supply voltage 18-50 VDC
Barrier type screw terminals, DIN rail mountable
Hardened against 150 MHz and 440 MHz radio interference
Wiring Harness
One wiring harness per device
NEMA 4 rated
Display Functions (Read Only)
Motor current
System air pressure
Copper Ground Bar
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
161
CMC TECHNICAL REFERENCE MANUAL
OPTIONS
Analog Inputs (Monitor, Alarm and Trip)
Any Temperature
Any Pressure
Any Vibration
Any 4-20 mA signal
Digital (Discrete) Inputs (Monitor and Alarm or Trip)
Low water flow
Dirty inlet filter (switch supplied loose)
Dirty oil filter
Low oil level
High condensate level (common for all traps)
High motor temperature
Any Discrete Input
Panel Enclosures
Cooing Fan with Filter
110/115 VAC, 50/60 Hz, 0.24 Amps, 20 Watts
Air flow with filter 36 CFM (61 M3/Hr)
NEMA 4 Enclosure
Space Heater, Vortex Tube Cooler
NEMA 4X Enclosure
Space Heater, Vortex Tube Cooler
Stainless steel or epoxy coated carbon steel
Space Heater
120 VAC, 120 Watts, finned strip heater
Bimetallic baseboard type thermostat set at 45 degF (7 degC)
Vortex Tube Cooler
25 SCFM (42 NM3/Hr) at 100 PSIG (7 BarG) of compressed air
1500 BTU/Hr (378 kCal/Hr), Thermostat set at 90 degF (32 degC)
Solenoid operated valve, Air Filter
Type Z Purge
Select-able quick and normal flow rates with meters
Differential pressure switch set at 0.2 inches (5 mm) of water
Loss of purge indication, Relief valve, Warning label
Fused Control Power Disconnect
Rotary handle through door, 30 amp fuse
Ground Fault Protector for UL Panels
120 Vac circuits protected against ground fault currents.
Control Electrical Package (Standard on CV)
Prelube Pump Motor Starter
Two horsepower and less
Available voltages 380, 460, 575 VAC
Maximum voltage rating 600 VAC, 10 Amp rating, 120 VAC coils
IEC Style
Heater Contactor
IEC Style, Adjustable ambient compensated overloads
Available voltages 380, 460, 575 VAC
Maximum voltage rating 600 VAC, 10 Amp rating, 120 VAC coils
Control Power Transformer
Machine tool type, 230, 460, 575 VAC to 120/95 VAC
500 VA or optional 1000 and 1500 VA, 50 or 60 Hz
Transient Voltage Surge Suppressor
UL 1449 Listed
Tested to ANSI / IEEE C62.41 category A and B environments.
Stage Data Package (Standard on CV)
Interstage Air Pressure and Temperature each stage
Alarm Horn
80-95 dBA, 2900 Hz
Running Unloaded Shutdown Timer
Timing range and mode select-able through CMC
Water Solenoid Post Run Timer
Timing range and mode select-able through CMC
Inlet Valve Tight Closure
Keeps inlet valve closed until motor reaches full speed
0-30 second timer range settable by IR Service Tech
Diesel Engine Driven Compressor Control
Steam and Gas Turbine Driven Compressor Control
Main Motor Starter (Wye-Delta)
NEMA Size 5 or 6
Open transition type, Ambient compensated overloads
Available voltages 380, 460, 575 VAC, 120 VAC coils
Power Regulating Transformer
120 VAC, 60 Hz, 250 VA
-65% Input Channel line variation, Output Channel +5-10% NEMA
Specification
±15% Input Channel line variation, Output Channel ±3%
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Automatic Starting
Automatic Hot Start
REMOTE FUNCTIONS DISABLED/ENABLED Selector Switch
Solenoid Valves for Intercoolers
CMC settable start up pressure setpoint
Post Run Water Flow Timer
Automatic Cold Start
CONTROL POWER LOCAL/OFF/ COLD Selector Switch
Strobe Light
Solenoid Valves for Intercoolers and Instrument Air Line
CMC settable start up pressure setpoint
Post Run Water Flow Timer
Start Timer
Lube Oil Alarm Bypass Timer
COMMUNICATIONS OPTIONS
Communications Card(s)
Up to three cards per module RS-422/485
Local/Network Selector Switch
Direct CMC Communication with RS422/RS-485
Requires programming application by customer
Utilizes standard MODBUS protocol or Allen-Bradley DF1 protocol for
PLC2, PLC5 and SLC500 devices
Hard Wired Communication
REMOTE FUNCTIONS DISABLED/ENABLED Selector Switch
Contacts for Remote Start/Stop, Load/Unload, Acknowledge/Reset
Trouble Indication Contacts (Alarm and Trip, Alarm Only or Trip Only)
Remote 4-20 for Pressure Setpoint
Running Unloaded Contact
Air System Controller (ASC)
Features
Sequencing, load sharing and energy management for eight (8)
compressors (more depending on network design and hardware)
A CMC Communication Adapter mounted in each CMC panel
Max distance from last compressor to Communication Adapter is 4000
feet (1218 meters)
Modbus to Ethernet Bridge
Ethernet Switch
ASC Personal Computer (running Server Software)
Pentium IV processor (Minimum 1.4GHz microprocessor)
256 MB RAM (512 Recommended)
144 MB 3.5 inch diskette drive
Network Interface card
Recordabel/Rewriteable CD ROM Drive
144 MB 3.5 inch diskette drive
Minimum 40.0 GB hard drive
CUSTOMER RESPONSIBILITIES
Three phase power
Clean, dry control air 80-150 PSIG (5.62-10.55 kg/cm2)
Control air tubing from control air header, 1/4 in (0.635 cm) FNPT
connection
Mount and wire external switches and field wired devices
Tuning control parameters for system
Current transformer – instrument grade
0-5 amp
Better than 1% accuracy
CONTROLLER OPERATING ENVIRONMENT
Electrical Operation
115 VAC ±5%
24 VDC Instruments except three wire RTDs
32 VA of AC power requirement
50/60 Hz AC supply frequency
Temperatures
Operating temperature 32 to 140 degF (0 to 60 degC)
Storage temperature -4 to 158 degF (-20 to 70 degC)
Relative Humidity
95% (maximum) non-condensing
DOCUMENTATION
Instruction book
Electrical schematic
Panel Outline drawing (Optional)
CMC TECHNICAL REFERENCE MANUAL
Glossary
The following glossary is generic; therefore,
some terms do not apply to all CMC systems.
AB — See Allen-Bradley.
Absolute Address — For Modbus compliant devices, the
specific memory location for a coil, discrete input, register or
analog input. The address is a five-digit number.
Accelerometer — An instrument used to measure
acceleration. These instruments are typically used for bearing
analysis.
Actuator — The device on a control valve that provides the
power to move the valve to a position. Typically, this power is
supplied through control air to open (for the inlet valve) and
close (for the bypass valve). For “fail-safe” operation, a spring
is used to drive the valve in the opposite direction.
Address — This term is used by PLC manufacturers to
indicate a specific memory location within the unit. These
locations typically reference the value for data items like analog
inputs, analog outputs, digital inputs, digital outputs, coils and
intermediate computational states. Through these memory
locations, the current system pressure, first stage vibration and
discharge air temperature can be determined.
Alarm — The term used to indicate that an abnormal condition
exists that should be addressed by an operator. This condition
has not reached a level that would shut down the compressor.
Alert — See Alarm.
Allen-Bradley — A manufacturer of control products, most
notably PLCs. These PLCs are used for various industrial
applications including controlling compressors.
American Wire Gage (AWG) — The measurement system
used to indicate the diameter of the wire. The gage number
increases as the wire diameter decreases.
Ambient Control — See Polytropic Head.
Analog Input — An electrical device, which represents a
specific real world pressure, temperature, vibration or current.
As these items fluctuate, the electrical signal to and from the
microprocessor board also fluctuates proportionally to the
amount of change. The electrical signal is typically in the form
of a current that ranges from 4 to 20 milli-amps in magnitude.
Analog Output — An electrical signal, which typically
represents the inlet and bypass valve position. As these valves
fluctuate, the electrical signal to and from the microprocessor
board also fluctuates proportionally to the amount of change.
The electrical signal is typically in the form of a current that
ranges from 4 to 20 milli-amps in magnitude.
Auto-Cold Start — A control mode that automatically
energizes the panel power, opens cooling water flow valve to
the coolers, turns on seal air, starts and loads the compressor
on a low pressure condition.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Auto-Dual — The control mode that automatically unloads a
modulating compressor when the bypass valve position
reaches a specified value or the check valve closes. Once
unloaded, this control mode will automatically reload the
compressor when the system pressure drops below a
specified value.
Auto-Dual Unload Timer  The time delay, in seconds, at
which the machine will be unloaded after the bypass valve
has passed and stayed below the unload point when
Autodual is active.
Auto-Hot Start — A control mode that automatically starts
and loads the compressor on a low-pressure condition.
Auto-Reload — The portion of Auto-Dual control mode that
automatically reloads the compressor when the pressure
drops below a specified value.
Auto-Start Pressure  The system pressure, in pressure
setpoint units, at which the machine will start when either
auto hot or cold start is active.
Axial Position — The position of the rotating assembly with
respect to the horizontal axis of the pinion.
Baud Rate — Unit of signaling speed for data
communications. The speed in baud is the number of line
changes (in frequency, amplitude, etc.) or events per
second. At low speeds each event represents only one bit
and baud rate equals bits per second. As speed increases,
each event represents more than one bit, and baud rate
does not truly equal bits per second.
BCM — Base Control Module. The device of the CMC that
receives all of the compressor inputs and outputs and makes
decisions about how the compressor is to operate.
Binary Signal — The type of signal used in
communications. Binary refers to the smallest size of data
being transmitted, a bit.
Blow-off Valve — Also know as a bypass valve or antisurge valve. This valve protects the compressor from surge
by bypassing a percentage of the compressed air to the
atmosphere, which results in keeping the compressor loaded
above the surge point.
BPS — Bits per second. Unit of signaling speed for data
communications.
Bridge — A device which forwards traffic between network
segments based on data link layer information. These
segments would have a common network layer address.
Bypass Valve — See blow-off valve.
CAT 5 — Category 5. A classification of cable used in
twisted-pair networks.
CE Mark — The CE Mark is a combination of various
individual European standards into one set of standards for
the entire European community. The Mark is a self
declaration and self marking process. Once you have proven
that the particular equipment meets the requirements of CE
1
2
Mark and have the data to back it up, you may mark the
product with the CE Mark.
Citect — One of many SCADA software packages that can be
used for air system integration.
Choke — Also know as stonewall. This is the maximum flow
that can be compressed by a given machine’s hardware
configuration.
Circuit Breaker — An automatic switch that stops the flow of
electric current in a suddenly overloaded or abnormally
stressed electric circuit.
CMC — Centac MicroController.
CMC System — Any combination of CMC control components
which when combined create a control system. The typical
CMC system consists of a Base Control Module (BCM),
Operator User Interface (OUI), and Power Supply (PS). A
common variation on the typical system is the addition of a
Universal Communications Module (UCM).
Coast Timer — The time interval, in seconds, between a
compressor stop or trip and the motor coming to a complete
stop. The timer is used to inhibit restarting.
Compressor Load, Load — The power consumption of the
compressor. It is typically indicated in amps, kilowatts, SCFM,
etc.
COM Port — See Serial Port.
Control Transformer — The transformer that is used to
reduce the incoming voltage (for the prelube pump motor and
oil heater) to approximately 120 volts for controlling the CMC
electrical devices (relays, power supply, etc.).
Control Valve — The inlet or bypass valve used to control
pressure or current.
Control Variable, Process Variable — The variable being
regulated. When at MinLoad the control variable is load for the
inlet valve and System Pressure for the bypass valve. When at
MaxLoad the control variable is load and when loaded the
control variable is System Pressure.
CSA Approval — Canadian Standards Association approval is
required for all electrical devices shipped into Canada. This
association is similar to UL for the United States and CE for
Europe.
CT — Current Transformer.
CT Input Channel — The current transformer input channel.
CT Ratio — Current Transformer Ratio. The current
transformer ratio used in displaying the motor current; e.g.
600:5 = 120.
Current Transformer — The electrical device used to
measure the amps of the main drive motor. For our standard
application, we only measure the current from one of the three
phases.
Daisy Chain — A method of wiring a communication network.
This method starts with the “master” and it is wired directly to
compressor #1. Compressor #2 is wired to compressor #1,
then compressor #3 is wired to compressor #2.
CMC TECHNICAL REFERENCE MANUAL
Data Link — A direct serial data communications path
between two devices without intermediate switching nodes.
Data Highway Plus — A communication protocol used by
Allen-Bradley PLC 5 and SLC500 PLCs.
DCS — See Distributed Control System.
degC — Degrees Celsius, Centigrade.
degF — Degrees Fahrenheit.
DH+ — See Data Highway Plus.
Derivative Mode — Provides a change in the control
variable (through the inlet or bypass valve) based on the rate
of change of the error (setpoint pressure minus system
pressure).
Derivative Constant — Also know as the rate time, in units
of seconds.
Design Point — The pressure and capacity required at
maximum ambient conditions.
Digital Device — A device, which is either on or off; e.g., the
N.C. contact on the seal air switch.
Discrete Device — See Digital Device.
Discharge Pressure — The gas pressure between the last
stage of compression and the check valve.
Distributed Control System — A system that attempts to
control an entire plant or process with multiple independent
local controllers by networking these local controllers to a
central computer through digital communications. These
central computers can be a PC, PLCs or other larger
systems. Some manufacturers of these DCS products are
Bailey, Honeywell, Allen-Bradley, Siemens, and others.
Drain Wire — An insulated wire in contact with a shield
throughout its length, and used for terminating the shield.
Dry Contacts — A set of contacts that require a power
source supplied by others (customer). This is the normal
type of contacts that we provide.
Electro-pneumatic — A term used to indicate a combination
of electronics and pneumatics. In the past, we provided
electro-pneumatic panels as standard equipment. With the
advent of digital computers, most all control panels are
electronic.
ERAM — Erasable Random Access Memory.
Event — The control transfer or “rule(s)” as used in State
Logic to transfer from one state to another.
FactoryLink — One of many SCADA software packages
that can be used for air system integration.
FLA — Motor Full Load Amps. The motor amperage at full
load, this value is found on the motor nameplate.
Flexible Conduit — Small diameter hose, made of plastic
coated aluminum, which is used to enclose wire from the
control panel to machine mounted instruments.
Fused Disconnect — As a safety precaution, this option
removes power from the panel before the door is opened. By
turning the rotary door handle, the panel power is
terminated. The disconnect would have to be mounted
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
external to the panel enclosure. The short circuit capacity,
maximum ground fault, motor full load amps, motor locked rotor
amps and motor voltage must be known to size the disconnect
properly.
Ground — A connection to earth or to some extended
conducting body that serves instead of the earth.
Ground Loop — An unwanted, continuous ground current
flowing back and forth between two devices that are at different
ground potentials.
Grounded System — An electrical system in which at least
one point (usually a wire) is intentionally grounded.
Head — See Polytropic Head.
High Load Limit — See HLL
HLL — High Load Limit. The load that the controller maintains
when at MaxLoad.
I/O — See Input/Output.
IBV — Inlet Butterfly Valve. See Inlet Valve.
IEC — International ElectroTechnical Commission is the
governing body of Europe for electrical equipment and codes.
IGV — Inlet Guide Vanes. See Inlet Valve.
Inlet Unload Position — The position of the inlet valve when in
the unloaded state.
Inlet Valve — The device used on the inlet pipe to the
compressor that restricts the amount of airflow to the
compressor. This valve can be a butterfly valve or a valve with
inlet guide vanes.
Input/Output —The hardware interface between the
compressor and the control system. This term generically
applies to the entire interface circuit including sensor, wiring,
and junction points.
Instrument Air — The air supply to the panel that is directed to
the power air system for the inlet and bypass valves and the
compressor seals.
Integral Mode — Provides a change in the control variable
(through the inlet or bypass valve) based on the time history of
the error (setpoint pressure minus system pressure).
Integral Time Constant—This value is expressed in repeats
per second and represents the number of times per second the
integral mode acts.
Intellution — One of many SCADA software packages that
can be used for air system integration.
Interface — The hardware or software device used to
communicate between products.
Interlock — An electrical function that prevents the
compressor from starting in the event that the function has not
been satisfied. For example, the seal air interlock prevents the
compressor from starting until the seal air pressure is
adequate.
IRBUS — The proprietary communication protocol used to
communicate to and from one or many Base Control Modules
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
(BCM), Universal Communication Modules (UCM) and
Operator User Interfaces (OUI).
Loopback — A diagnostic test in which a transmitted
communication signal is returned to the sending device after
passing through all or part of the communication network.
This test compares the transmitted signal to the received
signal. The test passes if the signals are identical.
MA, mA — Milliampere
Maintained Contact — A contact closure that remains
closed.
MaxLoad — The message displayed on the OUI Status Bar
when the machine is running at MaxLoad.
MinLoad — The message displayed on the OUI Status Bar
when the machine is running at MinLoad.
MMI — Man Machine Interface. The term used to indicate
the device or method used for a human to interface with a
machine. Typically these interfaces are LCD displays or
computer screens. For the CMC, the MMI is the Operator
User Interface (OUI).
Modbus — A sixteen-bit communication protocol originally
developed for Modicon PLCs. This protocol has become a
defacto standard for industrial equipment.
Modicon — A PLC brand name manufactured by Schneider
Automation.
Modulate — The control mode that opens and closes
(modulates) the inlet or bypass valve to maintain a constant
discharge pressure. This is the primary control mode for
centrifugal compressors.
Momentary Contact — A contact closure that closes and
then opens.
N.C. — Normally Closed. Used to indicate the state of a
contact when no power is applied.
N.O. — Normally Open. Used to indicate the state of a
contact when no power is applied.
Natural Curve — The set of pressure and capacity points
that define the operating characteristic of the centrifugal
compressor.
Natural Surge — The point on the natural curve that is
represented by the maximum pressure and minimum
capacity.
NEMA — National Electrical Manufacturers Association.
Network — A series of points, nodes or devices connected
by some type of communication medium.
On-Line/Off-Line — Control mode that allows the system
discharge pressure to fluctuate between two pressure
setpoints. The compressor will load when the actual
pressure is below the lower setpoint pressure and will unload
when it reaches the higher setpoint pressure. This type of
control mode is normally used on reciprocating and rotary
compressors.
3
4
CMC TECHNICAL REFERENCE MANUAL
OUI — Operator User Interface. The device on the CMC that
gathers user inputs and provides compressor operating status.
Parity — The addition of non-information bits to make up a
data transmission block that ensures the total number of 1s is
either even (even parity) or odd (odd parity). This is used to
detect errors in communication transmission.
Partial Unload — See Surge Absorber.
Password — The four digit parameter used to determine when
the user can modify setpoints. The range of this password is
0000 to 9999.
PID — Proportional, Integral, Derivative. The parameters used
to adjust the behavior of PID control loops.
PLC — Programmable Logic Controller. This hardware device
is configurable such that many types of analog and digital
inputs and outputs can be utilized to control various industrial
products.
PLC 5 — Type of Allen-Bradley PLC used for large
applications.
Pneumatic — Run by or using compressed air.
Polytropic Head — The energy in foot-pounds to transfer one
pound of given gas from one pressure level to another. (ft-lb/lb)
Positioner — The device on a control valve that instructs the
actuator how much (to what position) to move the valve.
PROM — Programmable Read Only Memory.
Proportional Mode — Provides a change in the control
variable (through the inlet or bypass valve) proportional to the
error (setpoint pressure minus system pressure).
Proportional Band Constant — The percent change in
system air pressure that causes a percent change in the valve
position. This value is dimensionless.
Protocol — A formal set of conventions governing the
formatting and relative timing of message exchange between
two communication systems.
RAM — Random Access Memory.
Relative Address — For Modbus compliant devices, the fourdigit address within the range of 0-9999. The relative address
can be determined from the absolute address by deleting the
type (the ten-thousandth place) and subtracting one.
Reload Percent — The reload pressure, in percent of user
pressure set point, at which the machine will load when
Autodual is active.
Rigid Conduit — Small diameter pipe, made of carbon steel
with welded connections, which is used to enclose wire from
the control panel to machine mounted instruments. This conduit
is typically used in hazardous area classifications.
Rise To Surge — The amount of pressure from the operating
pressure to the natural surge pressure. This amount is usually
expressed in percent.
RS-232 — Electronic Industries Association interface standard
between data terminal equipment and data communication
equipment, using serial binary data interchange. This is the
most common standard used by industry.
RS-232 to RS-422/485 Converter — A hardware device that
electrically converts an RS-232 signal into an RS-422 or RS485 signal.
RS-422 — Electronic Industries Association interface
standard that specifies electrical characteristics for balanced
circuits and extends transmission speed and distances
beyond RS-232. This standard is a balanced voltage system
with a high level of noise immunity.
RS-485 — Electronic Industries Association balanced
interface standard similar to RS-422, but uses a tri-state
driver for multi-drop applications.
RTD — Resistance Temperature Detector. An instrument
that measures temperature by detecting the voltage across
the RTD material (mostly platinum). The temperature is
determined because as the temperature increases the
resistance increases.
RTU — Remote Terminal Unit. A device typically used for
data acquisition to gather data. By using this definition, the
Base Control Module is an RTU.
SCADA — Supervisor Control and Data Acquisition. The
generic classification for software that gathers data for
control of industrial products.
Sequencer — A hardware or software device that controls
the order in which compressors starts, stops, loads and
unloads. Some sequencers also control loading and
unloading through incremental pressure setpoints among the
compressors. For example, in a three-compressor
application the setpoints may be 101 psi for compressor #1,
100 psi for compressor #2 and 99 psi for compressor #3.
Assuming the pressure transducers were calibrated within
one psi of each other and the machines were running
unloaded, this configuration would drive compressor #1 to
load first when the pressure dropped to 101 psi.
Serial Device — A Personal Computer (PC), Programmable
Logic Controller (PLC), Distributed Control System (DCS) or
any other device that can transmit, receive and interpret an
RS422/485 formatted signal.
Serial Port — The RS-232 connection on the back of a PC
to communicate with other equipment. This connection is
typically referred to as COM1. A single PC can have more
than one serial port.
Service Tool — The software used on the PC to configure,
tune, record and log data from the CMC.
Service Tool Plug — A port on Panel door to provide
access to IRBUS Network. Requires Laptop and external
UCM.
Setpoint Ramp Rate — The gradual increase of the system
pressure set point during a loading operation of the
compressor. The ramping of the system pressure set point
helps to smooth the transition and prevents a pressure
overshoot in the air system upon initial compressor loading.
Shielded Wire — Wire that has a sheet, screen or braid of
metal, usually copper, aluminum, or other conducting
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
CMC TECHNICAL REFERENCE MANUAL
material placed around or between electric circuits or cables or
their components, to contain any unwanted radiation, or to
keep out any unwanted interference.
SLC500 — Type of Allen-Bradley PLC used for relatively small
applications and is lower in cost than an equivalent PLC 5.
Start Timer — The time interval, in seconds, between pressing
the Start button and the compressor is running at full speed.
The timer is used to transition wye delta starters, inhibit
loading, de-energize the prelube pump, and disable the
alternate alarm and trip setpoints.
State — A task that is currently being executed in State Logic.
Only one state is active at one time.
State Logic — State Logic is an alternative to traditional
control languages used for machines, systems, and processes.
State Transition — The movement from one state to another
based on one or more events.
Status Bar — The Status Bar provides four distinct types of
information (Compressor Operating State, Compressor Status,
Compressor Control Location and Page Number). This region
is always visible from any folder and page combination.
Stonewall — See Choke.
Surge Absorber — The reaction of the control system to a
surge that pops the bypass valve open by a small percentage
to get the compressor out of the surge condition. This feature is
initiated by surge detection.
Surge Anticipation — The ability of a control system to
prevent surge by predicting that a surge is about to happen.
Surge Detection — The ability of a control system to indicate
that a surge has happened. This feature is important because a
persistent surge condition can damage the compressor. Once
detected, the control system can respond to the event by taking
a corrective action; i.e., by opening the bypass valve.
Surge Indexing — A method of automatically increasing the
setting of TL upon a surge.
Surge Indexing TL — The setpoint at which the inlet valve
controls to MinLoad.
Surge Line — A series of points that represent natural surge
for various inlet pressure conditions.
Surge PTX — Surge Pressure Transducer. Surge PTX is
mounted between the last compression stage and the check
valve.
Surge Sensitivity — A setpoint that is used to indicate the
magnitude of pressure and current changes that occur during a
surge condition. This setpoint determines when the control
system detects a surge.
Surge Unload — The reaction of the control system to a surge
that unloads the compressor to exit the surge condition. This
feature is initiated by surge detection.
Switch, Ethernet — A device connected to several other
devices. Transfers messages across the network.
System Pressure — The pressure at the location of the
system pressure transducer.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
Terminal Block — A device that is used to connect to wires.
Typically, these blocks are provided for customer field wiring
to the panel and when one wire is to be connected to
multiple devices.
Terminating Resistor — A resistor placed at the end of a
communication network for absorbing or sufficiently
attenuating signals incident on it so that they are not
reflected back into the transmission line at amplitudes where
they would cause distortion of the data signal. Typically, a
resistor is placed at each end of the network to help
eliminate noise.
Thermocouple — A device used to measure temperatures
accurately and consists of two dissimilar metals joined so
that a voltage is generated between to the contacts of the
two metals as the temperature changes.
Throttle Limit — See TL.
Throttled Surge — The condition created by closing the
inlet valve past the surge point to maintain constant
pressure.
Tight Closure — A term used to describe the inlet valve
position when the compressor is not running and starting.
The inlet valve ideally is closed tightly when stopped to
prevent reverse rotation of the compressor if the check valve
fails. Also, to reduce the load on the compressor during
starting, the inlet valve can be held closed for a short period
of time (less than thirty seconds) after the start button is
pushed. This is most typically done on compressors at high
altitude, most notably snow making applications. Bearing
analysis must be done prior to using this option.
TL — Throttle Limit. Establishes the minimum flow through
the machine when loaded, it is the maximum point of inlet
valve throttling. If system demand is below this throttle point,
the compressor must bypass air to maintain pressure
setpoint or unload.
TL increment value — When Surge Indexing is enabled, the
TL increment value is the amount added to the Surge
Indexing TL upon a surge. The Surge Indexing TL will stop
being incremented when and if the value reaches MaxLoad.
Transducer — An electrical device that provides a usable
output (4-20 mA, 0-5 vDC, etc.) in response to a measured
property (pressure, temperature, etc.).
Transformer — An electrical device that transfers energy
from one circuit to another by electromagnetic induction.
Transient Voltage Surge Suppressor — An electrical
device that prevents temporary over-voltages of short
duration (typically associated with lightning strikes and
ground faults on an ungrounded system) from damaging
other electrical equipment.
Transmitter — An electrical device that sends the digital
representation of a real measured value (e.g., pressure,
temperature), to the BCM in the control panel for analysis
and display.
Turndown — The amount of capacity that can be decreased
from full load (maximum load) at a constant pressure before
5
6
CMC TECHNICAL REFERENCE MANUAL
the bypass valve begins to open to avoid surge. This amount is
usually expressed as a percent of full load capacity.
TVSS — See Transient Voltage Surge Suppressor.
Twisted Pair Wire — Paired cables allow balanced signal
transmission, which results in signals with low noise. Due to the
improved noise immunity of twisted pairs, data speeds are
usually higher than those of multi-conductor cables.
UCM — Universal Communications Module. The device that
allows outside systems to communicate with the CMC.
UL — Underwriter’s Laboratory.
Ungrounded System — An electrical system, without an
intentional connection to ground.
Unload — The operating mode that passes a small amount of
air through the compressor and bypasses it to the atmosphere.
In this mode, the inlet valve is cracked open a small amount
and the bypass valve is fully open. This mode is used when
starting the compressor before loading, stopping the
compressor and during periods of no demand.
Unload Point — The bypass valve position, in percent open, at
which the Autodual unload timer will start timing to unload the
compressor when Autodual is active.
User Pressure Set Point — The local control pressure set
point.
Valve Stroking — The process of calibrating the valves to
align the fully open position to 100 percent and the fully closed
position to 0 percent of output signal.
VDC — Volts Direct Current
Voltage Regulator — An electrical device that maintains
voltage to a predefined level.
Wait Timer — The delay interval, in seconds, between power
up and the ready state.
Wire Gage — See American Wire Gage.
Wonderware — One of many SCADA software packages that
can be used for air system integration.
Z-Purge — Required when the customer environment is
Division 2. A Type Z Purge reduces the classification within an
enclosure from Division 2 too non-hazardous. When provided,
a NEMA 4 or NEMA 4X enclosure is required. Hand valve
selectable quick and slow purges, with flow meters are
provided to regulate the amount of gas entering the panel. A
differential pressure switch is wired to a light on the front of the
panel to indicate if there is a loss of purge gas. A relief valve is
installed to prevent over-pressurization and a warning label,
text below, is affixed to the front of the panel.
22204796 Rev. B, Version 3.10
 1996-2003 Ingersoll-Rand Company
Date of Issue: March 24, 2003
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