I don't see why my step/dir servo setup would be any different from a step motor + encoder config. (Obviously, PID settings would be different as they would be machine specific.)
One thing to remember the PID loop will likely not be able to correct for a stalled step motor. A few missed steps should be recoverable, but if a step motor stalls, the PID loop will command faster and faster velocities, trying to catch up to where it thinks it should be, making the stall worse. ----- Original Message ----- From: "Tom Easterday" <tom-...@bgp.nu> To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> Sent: Tuesday, June 20, 2017 10:15:01 AM Subject: Re: [Emc-users] following error only while homing Hmm, it seems like I failed miserably trying to do that when I first built the machine (this was my first build and Linuxcnc endeavor) back in 2010. I have a vague recollection someone suggested that as a method of using encoders with steppers. Seems like I spent a bunch of time flailing with getting the pid to work and ultimately gave up. Perhaps I could attempt it again...I assume it would be identical to setting up a typical servo system? > On Jun 20, 2017, at 9:59 AM, Todd Zuercher <zuerc...@embarqmail.com> wrote: > > What if you set up the stepgens in velocity mode with PID (I understand that > it is the better way to do hardware stepping with Mesa cards anyway.) This > is how I have my step/dir servos configured (using the encoder feedback for > the PID loop rather than the stepgens dummy position feedback. > > ----- Original Message ----- > From: "Tom Easterday" <tom-...@bgp.nu> > To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> > Sent: Tuesday, June 20, 2017 9:49:51 AM > Subject: Re: [Emc-users] following error only while homing > > Todd, the ini and hal config were in the first post.... > >> On Jun 20, 2017, at 9:21 AM, Todd Zuercher <zuerc...@embarqmail.com> wrote: >> >> I just checked my config on my step/dir servo machine, and it is homing to >> index on 2 of the axis. It is not having and problems. Maybe you have a >> configuration problem. >> Could you post a copy of your ini and hal file somewhere where we could >> check it over. >> >> ----- Original Message ----- >> From: "Tom Easterday" <tom-...@bgp.nu> >> To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> >> Sent: Tuesday, June 20, 2017 9:00:22 AM >> Subject: Re: [Emc-users] following error only while homing >> >> Andy, you are correct it is related to using index. Homing works fine if I >> don't use index. The encoder reset makes sense as to why it CAN happen (but >> shouldn't be). Is this just a bug? I would try to home a second time but >> as Todd says, I can't clear the error. Linuxcnc shuts off when it happens >> and pressing on just immediately faults again. I have to exit and restart >> it. >> >> -Tom >> >>> On Jun 20, 2017, at 8:13 AM, Todd Zuercher <zuerc...@embarqmail.com> wrote: >>> >>> >>> ----- Original Message ----- >>>> From: "andy pugh" <bodge...@gmail.com> >>>> To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net> >>>> Sent: Tuesday, June 20, 2017 4:27:46 AM >>>> Subject: Re: [Emc-users] following error only while homing >>>> >>>>> On 20 June 2017 at 03:51, <tom-...@bgp.nu> wrote: >>>>> >>>>> Why would I get a following error only while homing >>>> >>>> >>>> I think it is probably because you are using HOME_USE_INDEX (which >>>> will >>>> zero the encoder at the index pulse) and feeding the encoder feedback >>>> back >>>> into LinuxCNC. >>>> >>>> Now, this is perfectly normal, and with a servo / pid machine the >>>> system >>>> knows to ignore the f-error immediately after an encoder reset. What >>>> is >>>> puzzling me here is why it isn't working in this case. I think it is >>>> something to do with the fact that your system is set up for >>>> open-loop step >>>> position control but has encoder feedback. However I can't >>>> immediately see >>>> why this makes a difference. >>>> >>>> I imagine that if you press the home button again it will home Z >>>> seamlessly, and then f-error homing the next axis. >>>> >>>> >>>> -- >>>> atp >>> >>> Andy, >>> >>> I wish that were true. For some reason my analog servo machine trips up >>> and sets a following error on an axis about 25% of the time when trying to >>> home to index for the first time after turning on LInuxcnc. (Almost every >>> time since it is a 4 axis machine.) But the alarm is easily cleared, and >>> it always homes fine the 2nd try. I have never been able to figure out >>> why, and no one else seems to have been able to replicate the problem. >>> >>> His problem sounds different since he says can't clear the alarm. >>> >>> My other machine with step/dir servos, doesn't have encoder index to home >>> to. But it does home fine without ever setting following errors. >>> >>> ------------------------------------------------------------------------------ >>> Check out the vibrant tech community on one of the world's most >>> engaging tech sites, Slashdot.org! http://sdm.link/slashdot >>> _______________________________________________ >>> Emc-users mailing list >>> Emc-users@lists.sourceforge.net >>> https://lists.sourceforge.net/lists/listinfo/emc-users >> >> >> ------------------------------------------------------------------------------ >> Check out the vibrant tech community on one of the world's most >> engaging tech sites, Slashdot.org! http://sdm.link/slashdot >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> >> ------------------------------------------------------------------------------ >> Check out the vibrant tech community on one of the world's most >> engaging tech sites, Slashdot.org! http://sdm.link/slashdot >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
