Balluff Basics - Micropulse Linear Position Sensors

Balluff Basics
Absolute vs Incremental Magnetic Encoders
Comparison of absolute and incremental measurement systems
What is the difference between absolute and incremental magnetic encoders?
vs
Absolute
How it works
Incremental
The sensor head glides over the tape which is encoded with magnetic poles. Internal magnetic sensors detect the encoded
information – similar to an audio cassette tape.
Sensor Head
[top view]
Sensor Head
[top view]
Strengths
Incremental
track
Incremental
track
Absolute
track
Reference
track
The measuring system returns the absolute value of
the current position. This absolute position information
is immediately available even after power loss, without
homing.
The measuring system returns the relative value of the
current position. It delivers positive or negative pulses
(increments), according to the direction of travel.
After power-loss the current position is not known, so
homing is required.
nAbsolute position value available immediately after
power-on; no homing required
nLong measuring length, theoretically infinite
nDiagnostic information increases position data
reliability
nLower cost
nCompatible with nearly all controllers
nSynchronized data protocol enables real-time
applications
nHigher overall cost than incremental systems
nUsually higher mechanical accuracy required
nMaximum measuring length dependent upon track
coding scheme
Common
applications
nHoming required to identify current absolute
position
nLimited diagnostic information
nLower position data reliability
Absolute Linear Encoders
Incremental Linear Encoders
nPick & Place systems
nAutomated assembly and packaging
nDispensing systems
nStorage and retrieval systems
nX-Y-Z machine axis positioning
nMotion systems – speed control
Typical
examples
BML S1G Absolute Magnetic Linear Encoder
Balluff Inc.
1-800-543-8390
www.balluff.us/basics
Balluff Canada Inc.
1-800-927-9654
www.balluff.ca/basics
BML S1F Incremental Linear Encoder
Balluff de México SA de CV
++52 442 212-4882
www.balluff.mx/basics
BB_011 • BML Absolute vs Incremental Magnetic Encoders • 2015-04
Challenges