On 07/27/2018 02:39 PM, Kurt Jacobson wrote: > So the question is, why did LCNC choose to use relative positions for the > probe parameters? There must be a good reason to not follow what seems to > be a standard among other controllers, but the only advantage I can see is > when probing to measure/scan a part, but in that case it would be very easy > to convert the ABS probed pos to relative by subtracting the WCO.
I don't know why the decision was originally made, but I can see the argument for having both available. When measuring a part using probing and logging, having the probe location in the part's coordinate system (ie, in the workspace coordinate system) makes things simpler. When probing a part in order to set the coordinate system to the part, having the probe location in absolute coordinates makes things simpler. > Trying to think of ways to make the behavior more expected for people > coming from other controllers, and at least make it clear in the docs . > Would it make sense to change parameters 5061-5069 to be the ABS probed > pos, or maybe allow using G53 with G38? I think it would also make sense if > `stat.probed_position` was consistent with the 5061-5069. I don't think we should change the meaning of existing parameters or fields, because doing that would break existing functionality. I would prefer adding nine new Interpreter parameters containing the *absolute* probe location, and adding a new field to the Status buffer (and the 'stat' variable in the linuxcnc python module) containing the probed position in *work coordinates*. The probe position is originally determined by Motion, which operates *only* in absolute coordinates. The probe information is relayed from Motion to Task via the Motion Status buffer, and Task converts it to the currently active workspace coordinates. The Interpreter (and thus the Interpreter parameters #5061 through #5069) use these converted workspace coordinates. The 'stat.probed_position' variable in the linuxcnc python module gets its info straight from Motion (again via the Motion Status buffer), so it sees the absolute coordinates. -- Sebastian Kuzminsky ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
