Installation guide

Keyword Reference Guide

MN1270 02.2002 39

Attributes:

Controller Read Write Command Multi-

Axis

Scaled Default Range

NextMove

 

0 -8388607.0 -

8388607.0

Description:

The

BACKLASH keyword controls the size of the backlash on an axis. Backlash describes the amount of

free movement in the gearbox or belts linking a motor and the physical axis. Backlash compensation

automatically compensates for this free movement whenever the axis changes direction. The

compensation method used is known as constant compensation and is turned on with the

BACKLASHMODE keyword. The rate at which compensation is applied is controlled with the

BACKLASHINTERVAL keyword.

The sign of the backlash is used to indicate in which direction the backlash was taken up during the

homing cycle. If the initial home direction was positive, then the backlash size should be specified as a

positive value. If the initial home direction was negative then the backlash size should be specified as a

negative value. It is recommended that homing is only performed on a switch and not the encoder index

pulse when using backlash compensation.

Example:

BACKLASH[0,1] = 0.01, -0.2

This indicates that backlash on axes 0 and 1 is 0.01 and 0.2 user units respectively. Axis 0 has homed

in a positive direction and axis 1 in a negative direction. If the first move after homing on axis 0 was in

a negative direction, then no compensation would be necessary. If the move was in a positive direction,

then the size of the backlash would need to be compensated for.

Reading axis position will show the compensated position. The axis must be

idle in order to change

the backlash value. The default backlash is zero.

See section 3.4 for further details on backlash compensation.