It really sounds like e-offsets (more correctly external offsets) are designed with your application in mind. Docs Ref: https://linuxcnc.org/docs/stable/html/motion/external-offsets.html
Here is another perhaps more relevant example where the Z axis height is compensated by external offsets. The machine thinks the plate being cut is flat and level. The external offset is managed by using torch voltage as the process control variable to maintain a constant height between the plate and the torch tip. https://youtu.be/5uJzgNeLSxs?si=RAQM8wS89dwyoMKj External offsets are named because they are external to the motion planner so I am not sure if your concerns about where they are applied are valid because the motion planner has no knowledge of the offset applied. Finally, I might add that if you are competent in C and the core of your requirement is real time, why complicate it by adding a non-real time Python component. it sounds like the new HAL port feeding external offsets would do the job in C and in Real time. Rod Webster 1300 896 832 +61 435 765 611 Vehicle Modifications Network www.vehiclemods.net.au On Sat, 18 Nov 2023 at 03:13, Ted <laser...@gmail.com> wrote: > > Sam- > yes the pins behave in realtime but the two example components I was > discussing > https://github.com/cnc-club/linuxcnc-engraving-comp/blob/master/compensation.py > and > https://github.com/scottalford75/LinuxCNC-3D-Printing/tree/master/compensation > are userspace python and *not* realtime. > > However of more import than the response of those pins is that they > happen far too late in the calculation chain - I need to make my changes > immediately after (encoder feedback) and before any machine coord / > workpiece coord / tool comp offsets come into play, so the e-offsets are > not feasible for this. > > Thanks, > TH. > > > > On 11/17/2023 11:51 AM, Sam Sokolik wrote: > > are you talking e-offset pins? Those are realtime.. I am using a realtime > > comp to do spindle synced motion... It works great.. > > > > https://www.youtube.com/shorts/nViXP9SsdWc > > > > sam > > > > On Fri, Nov 17, 2023 at 10:39 AM Ted <laser...@gmail.com> wrote: > > > >> On 11/17/2023 10:49 AM, andy pugh wrote: > >>> Is this related to wanting to do height mapping, or laser rastering, > >>> or something? > >> The end result is a multi-layer z-height and x-y-z-thermal compensation > >> system. (Yes, I know we have the "compensation" components, but both > >> offerings present by pushing data into the LCNC "offset" pins which is > >> far too late in processing for my application, as well as being purely > >> userspace). I need to be able to do my compensation directly after the > >> mag scales I have attached (to my CMM - a larger project scope) and > >> before any other value modification or motion decisions. > >> > >> I looked at raster also; at first pass it might be a little too involved > >> as designed, but using hal_port with less complexity might be quite > >> viable. The next question would be to see if I will need to "chunk" that > >> data or if I can single-blob it all without losses. Not having the > >> realtime side need to handshake back to the userspace would be a > >> preferred path for stability. (Says he who grew up with 25 pin serial > >> ports...) > >> > >> Thanks, > >> > >> TH. > >> > >> > >> -- > >> This email has been checked for viruses by Avast antivirus software. > >> www.avast.com > >> _______________________________________________ > >> Emc-developers mailing list > >> Emc-developers@lists.sourceforge.net > >> https://lists.sourceforge.net/lists/listinfo/emc-developers > >> > > _______________________________________________ > > Emc-developers mailing list > > Emc-developers@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-developers > > > > -- > This email has been checked for viruses by Avast antivirus software. > www.avast.com > > > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
