Is there a way to set backlash compensation in mach3 control or the galil controller

There is no command per-se, AFAIK you have to write a routine to do this, there is the MR command that may be able to be used, or there is a Backlash Compensation routine shown in this Galil manual.
http://www.electromate.com/db_support/downloads/ManualV3.pdf
I have not tried it.
Normally on a CNC machine the backlash comp is taken up in one particular direction, when a position is reached and the axis is reversed in the B.L. take up direction, the axis will move at a high rate by the amount of the recorded backlash.
Nosmo.

Backlash can be set in CONFIG>BACKLASH. As Nosmo reponded it is implemented on change of axis direction.
The backlash settings determine how fast it will be implemented. Works quite well.
RICH

I should have stressed  there is no GALIL command per-se.
If Mach has it then obviously you don't need to bother with the other routines.
 Nosmo.

I don't think the backlash works with the galil plug in installed i tried it but no noticeable difference

The Galil plugin just follows what Mach says.  If Mach is correcting for backlash, then the Galil plugin would not hinder it.  Test is by setting backlash to some insane value.

Steve