Rockwell Automation 8520-ARM2 9/Series CNC AMP Reference Manual Documentation Set - Manual (Page 176)

Servo Parameters
Chapter 7
7-30
Figure 7.18
Example of Reversal Error
Encoder mounted on
back of servomotor
Gear driven
by servomotor
Reversal Error Compensation distance
Axis driven by gear
When axis motion is commanded in the opposite
direction, the motor and attached encoder can move
this far without causing any axis motion
Axis Parameter Number Axis Parameter Number
(1) [1340] (7) [7340]
(2) [2340] (8) [8340]
(3) [3340] (9) [9340]
(4) [4340] (10) [10340]
(5) [5340] (11) [11340]
(6) [6340] (12) [12340]
Range
--9.99999 to 9.99999 mm
or
--0.39366 to 0.39366 in.
Notes
This parameter must be set independently for each axis.
When activated, reversal error acts on all axis moves including manual
jogging and homing.
On systems using a 3--axis servo, the control commands the reversal error
to be taken out as a COMMAND. On systems using a 4--axis servo, the
control commands the reversal error to be taken out as a FOLLOWING
ERROR.