Rockwell Automation 999 IMC S Class Compact Motion Controller (Cat. No. 4100-999-122) - Manual (Page 121)

Understanding IMC-S/23x Setups 5-41
Publication 999-122 - January 1997
Note that the position lock tolerance value is interpreted as a ± quantity.
For example, if your position units are Inches, specifying a position
lock tolerance of 0.01 provides a minimum positioning accuracy of
±0.01 inches as shown below.
Backlash Offset
When either UNIDIR APPROACH or LOAD REVERSAL backlash
compensation is selected in the application setup menu, a value for the
backlash offset must be entered. Enter a value equal to the desired
distance in axis position units that the axis should overshoot when
approaching the destination position from the opposite direction
(
UNIDIR APPROACH ) or add/subtract from the axis’ absolute position
whenever the axis changes direction ( LOAD REVERSAL ).
Approach Direction
When UNIDIR APPROACH backlash compensation is selected in the
Application setup menu, a value for the approach direction must be
selected. Toggle to the desired direction (
POSITIVE or NEGATIVE )
from which all moves will approach the destination position.
For example, if the approach direction is POSITIVE , the axis
approaches the destination position from the positive direction. In other
words, moves approaching the destination position in the positive
direction operate normally. Moves approaching the destination position
from the negative direction "overshoot" the destination position by an
amount equal to the backlash offset, and then move back to the
destination position in the positive direction as shown below.