If I try to use the GO TO WORK ZERO button after performing the Touchoff for the Z axis I got an error "Cannot use G53 incremental".
By reading other posts I learned that I would need to change from G91 to G90 before it would work.

In my logic, if I prefaced the GO TO WORK ZERO button code so that it first issued a G90 it would work. And it does.

So... my code line is like this.....    mc.mcCntlMdiExecute(inst, "G00 G90\nG00 G53 Z0\nG00 X0 Y0\nG00 Z0")--With Z moves

Are there any negatives to doing it this way? Should I setup a routine for the button to see if I am in G91 then do the switch to G90 and switch back after I have moved to the work offset?

Thanks

Hi,
I found this on page 385 of Peter Smids book 'CNC Programming Hanbook' 2nd ed. related to the use of the G53 command.

The upshot is that G53 is ALWAYS an absolute command.

Craig

G53 is not a work offset like G54-G59.  G53 is your actual machine position. 

I think the problem arises when the Set to Work Zero script trys to use G53 while in incremental mode. For now I am going to leave the modified line in that script and flip to G90 before executing the G53.
When I have a little time I will modify the script to check for the current mode and if it is G91 switch it to G90 then switch back to G91 at the end.
Chuck