EMC and G28

[Stephen Tate <stephentate-at-email.msn.com>]

I am in the process of modifying the Fanuc Postprocessor in Mastercam for 
use in EMC.  However, I am not sure how to handle the G28 command, which is 
generated by the Postprocessor and not supported by EMC.  I have modified 
the Post Processor to Generate a G0 Z.0 then a G0 X.0 Y.0 on the next line 
in the place of G28. This approach, however, seems to lead to problems when 
I change tools.  My BOSS always trips the Z+ limit switch.  I assume this 
is caused by G43 calls which stack up on top of the current Z0. Reference 
point.  Is there a way to implement a relative return to the last reference 
point under the limits of EMC?