Probe Basic subroutine parameter - #5210?

Updated PB and need to re-do all the numbered parameters in my customized tool change subroutines.

While digesting the subroutines, I found that parameter #5210 is used twice:

unload_spindle.ngc
M61 Q0
G49
#5210 = 0
#3991 = 0

M13
M61 Q#3991 G43 H#3991 #5210 = 0

According to the LCNC docs, #5210 appears to be written by LCNC if G52 or G92 offset is applied.  I'm guessing this is not normally a user-writable parameter.

Is this an error, or am I misunderstanding something?

Looks like I asked this question a couple years ago.  Memory failing.

forum.linuxcnc.org/qtpyvcp/46414-probe-b...eter-question#247625

If #5210 is intended (in LCNC) to be a 'flag' which indicates a G52/92 offset is applied, then writing to #5210 directly seems to be the wrong way to clear offsets.  And may, in fact, not clear out any offsets.

If the PB toolchange intention is to disable G52 or G92 offsets, G92.2 (or 92.1) could be called in the subroutine and a check for #5210 = 0 could be made to ensure the offsets are cleared.

Or a comparison made: if #5210 = 1, then G92.2 (or something like that).

I'll have to test this out and see if manually zeroing #5210 changes applied G52/92 offsets.

If one interprets the explanation of #5210's function as being "disable G52 & G92 offsets", then it's perfectly appropriate to use it they way they did.

Assuming we're right about the fact that it's a flag (not a switch), my suspicion is that the ATC subroutine author(s) simply misinterpreted the purpose of #5210.

 

Aciera wrote:

I certainly hope there is no such wording in any of the documentation.

I think it's not painfully obvious - at least to me.  The G-code Overview section:

I think it's possible to misinterpret that statement.

Not until you dig deeper in other sections of the manual is the behavior a bit more clear.  From G-code/Coordinates/G92 Persistence Caution (5.3):

I think the solution is to remove the #5210 parameter, and add G92.2 to the very beginning of the toolchange sequence, and G92.3 to the very end.  That way any offsets used in a program are restored and not just erased after a tool change.

BTW, the "M61..." is from one of the GUI screen buttons (UNLOAD SPINDLE BUTTON)

Looking back at the old thread I linked, it's pretty clear I - and the PB Dev who was responding - thought #5210 was for setting/clearing G52/92 offsets.

I don't know why the author would want to clear the offsets during a spindle unload.  The original subroutines had a bunch of numbered parameters added by the authors - this may have been a mistake and they overlooked the fact that #5210 was already in use.

And yes, I, too, am convinced this is a mistake.  I'll raise an issue on PB-GH tonight.

Thanks for kicking this around with me.