Re: G92

["Les Watts" <leswatts-at-alltel.net>]

That is a good example Dale- thanks.

I call G92 an offset simply because the authors of the program
call it that. It's just a name.

The problem with G92 and possibly the G54 commands as I see it
is the way they are implemented in the controller.

Whichever is used (for whatever reason) I think if the machine display
doesn't SHOW that the commands are in effect in the display registers
it is gonna cause big problems.

So far I find that G92 IS STICKY in BDI 2.14+after a normal M2, M30,
 or emc shutdown. BUT IT DOESN"T SHOW IT! The last update I find is
this:
----------------------------------------------------------------------------
-----------------------------------------------
19-Feb-1999  FMP added setting of parameters 5211-5213 in
  convert_axis_offsets() and rs274ngc_init()
  17-Feb-1999  FMP took axis_offset_x,y,z out of origin resetting in
  convert_stop(), so that the G92 axis offsets persist after a program end.
  Previously they were cleared, and since they were not recorded in the
  parameters there was no way to recover them.
  12-Feb-1999  TRK fixed convert_stop so that offsets were set to zero,
  fixing a bug in G92; FMP checked into RCS; added this header and the
  RCS ident tag.
----------------------------------------------------------------------------
-----------------------------------------------

And that is from the latest sourceforge .tar.

I have already collected code snippets of the relevant areas where
G92 and G54 commands are defined and some of it looks funny
(or I am not understanding it). In particular when offsets are assigned
from file parameters.

Unfortunately I do not know tk/tcl programming so I can only kind of read
it.
I will leave that to experts like Ray. It kind of looks like hard zeros are
assigned to offset registers at initialization, but i'm not sure.

I will send the snippets to anyone who wants to read them, or publish
here. Might save a search for some of you.

Les


Leslie Watts
L M Watts Furniture
Tiger, Georgia USA
http://www.alltel.net/~leswatts/wattsfurniturewp.html
engineering page:
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