On Wed, 11 Jan 2017, Gene Heskett wrote: > Date: Wed, 11 Jan 2017 21:50:19 -0500 > From: Gene Heskett <ghesk...@shentel.net> > Reply-To: "Enhanced Machine Controller (EMC)" > <emc-users@lists.sourceforge.net> > To: emc-users@lists.sourceforge.net > Subject: Re: [Emc-users] Two questions. > > On Wednesday 11 January 2017 13:34:50 Peter C. Wallace wrote: > >> On Wed, 11 Jan 2017, Jon Elson wrote: >>> Date: Wed, 11 Jan 2017 10:36:18 -0600 >>> From: Jon Elson <el...@pico-systems.com> >>> Reply-To: "Enhanced Machine Controller (EMC)" >>> <emc-users@lists.sourceforge.net> >>> To: "Enhanced Machine Controller (EMC)" >>> <emc-users@lists.sourceforge.net> Subject: Re: [Emc-users] Two >>> questions. >>> >>> On 01/10/2017 10:45 PM, Gene Heskett wrote: >>>> On Tuesday 10 January 2017 23:02:28 Jon Elson wrote: >>>>> On 01/10/2017 08:39 PM, Gene Heskett wrote: >>>>>> But if I hook up the halscope, the apparent quadrature error is >>>>>> worthless due to the 1KHz servo-loop timing limiting the >>>>>> bandwidth. >>>>> >>>>> Well, that's why we use hardware encoder counters, as >>>>> sampling the quadrature at 1 KHz just isn't fast enough. >>>>> >>>>> Jon >>>> >>>> Plz elucidate Jon. Something has got to be better than this. See >>>> the pix I posted with the last reply to Peter & the list. The top, >>>> white trace in the halscope screen is the quadrature noise, easily >>>> 10x the timing wibbles I see on the hitachi's screen. >>> >>> If you are looking at the quadrature signals at a 1 KHz >>> sampling rate, then unless the encoder is moving quite >>> slowly, the sampling will be too coarse. That screen shot >>> is kind of small (you can take just a single window as the >>> screenshot, by the way) but it looks like the duty cycle of >>> the encoders is not 50%. That may well be aliasing, as the >>> quadrature signals seem to be moving much too close to 1000 >>> Hz. You'd get much better results below 100 Hz. Or, with >>> Mesa hardware, you can sample these with the base thread. >>> >>> I can't comment on the velocity output from the Mesa, as I >>> don't know their gear (or driver). But, the scale is 2/div, >>> meaning the scaled velocity output is jumping around 2 user >>> units up and down at a KHz rate. Clearly, not good. >>> >>> Jon >> >> The velocity output is calculated by using the number of counts >> divided by the time between the counts (time measured via a 1 MHz >> timestamp). If you have less than 2 counts per servo period the >> velocity estimation accuracy depends heavily the quadrature >> phase/symmetry since the edge spacing entirely determines the >> estimated velocity at this speed range. >> >> I suspect what Genes plot shows is that he has significant quadrature >> phase/symmetry errors at the FPGA inputs. >> >> >> Again here is a velocity plot of a accurate 100 Hz quadrature signal: >> >> http://freeby.mesanet.com/100_Hz_quadrature_velocity.png > > I've not played with the stepgen type 2 yet, but I have adjusted the > quadrature a few thousandths and reduced it by about 1/3rd. Thats > helpfull as I can filter to smooth a tach dial once I have defeated the > noise. > > But I have another concern. I have had to do a full powerdown reset to > clear a watchdog bite. The original config was I think intended to clear > it by re-enabling the machine, but I could nolinuxcnct, so I disconnected that > reset in the hal file I started with as the logic was self feeding, > locking out the ability to reset the disabled machine. And I couldn't > even do it from the halconfig as it claimed another signal was driving > it when I tried to setp that pin. > > Do you, Peter, have a logic diagram I can re-construct for that, that > actually works?
You need to restart linuxcnc to clear a watchdog bite >> >> >> >> Peter Wallace >> Mesa Electronics >> >> (\__/) >> (='.'=) This is Bunny. Copy and paste bunny into your >> (")_(") signature to help him gain world domination. >> >> >> ---------------------------------------------------------------------- >> -------- Developer Access Program for Intel Xeon Phi Processors >> Access to Intel Xeon Phi processor-based developer platforms. >> With one year of Intel Parallel Studio XE. >> Training and support from Colfax. >> Order your platform today. http://sdm.link/xeonphi >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > Cheers, Gene Heskett > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > Genes Web page <http://geneslinuxbox.net:6309/gene> > > ------------------------------------------------------------------------------ > Developer Access Program for Intel Xeon Phi Processors > Access to Intel Xeon Phi processor-based developer platforms. > With one year of Intel Parallel Studio XE. > Training and support from Colfax. > Order your platform today. http://sdm.link/xeonphi > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your (")_(") signature to help him gain world domination. ------------------------------------------------------------------------------ Developer Access Program for Intel Xeon Phi Processors Access to Intel Xeon Phi processor-based developer platforms. With one year of Intel Parallel Studio XE. Training and support from Colfax. Order your platform today. http://sdm.link/xeonphi _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users