On Tuesday 04 August 2020 08:37:06 Matthew Herd wrote: > Sorry for the delayed reply. I did some work on the scope on Sunday > morning and have attached some pictures of the results. Let me know > if they don’t come through. > > In sort, the results appear to show a roughly 80kHz noise when the > machine is turned on, with spikes pretty frequently exceeding 2V > (where my trigger was set for channel 1, the index channel. Channel 2 > was the A channel of the encoder and the noise also appeared on there. > Results were identical regardless of whether the encoder was > connected to the USC board or not. Spindle on/off appeared to have > little or no impact on the noise. I also got a picture of the Hal > Scope for the index pin and it is triggering repeatedly as discussed > before. I wasn’t able to reproduce the sawtooth on the > motion.spindle-revs during G33.1, but it was still randomly failing to > reverse and retract out of the hole occasionally. I ran a program > with numerous cycles and it’d e-stop the machine after a few G33.1’s > for reasons unknown. The encoder wires are twisted pairs and they’re > only separated to allow connection to ground. > > Given these findings, it appears that I’ll be rewiring the grounds to > a single point in the near future. I’ll re-test once that is done, > but it’ll be a few weeks. I was looking it over and while I didn’t > connect everything to a single point, I did do a fairly thorough job > of making sure each one was on a separate bolt on the case of the > respective enclosures. I’m wondering if there’s any value in > isolating power and logic grounds or isolating either one from the > machine. > Machine frame must be grounded to that bolt, I have a roll of 3/8" wide braid I use for that. And it would not hurt a thing to ground the table to the machine frame by the same method. If you do any shade tree EDM on that machine, like burning out a broken tap, I ground whichever polarity of the EDM supply that stands the best chance of not causing any arcing in the spindle bearings, that can be death on those.
> > On Aug 2, 2020, at 11:34 AM, Jon Elson <el...@pico-systems.com> > > wrote: > > > > On 08/01/2020 01:37 PM, Matthew Herd wrote: > >> Thanks Gene, I hope you’re well also. I disconnected that > >> grounding wire, no difference observed in the > >> ppmc.0.encoder.03.index behavior. The noise seems the same both > >> when spindle is running and stopped, with a tendency strongly > >> toward "true" than "false." Pulses seem to be both long and short, > >> but I’d guess they’re about 80-90% true. Not at all what I’d > >> expect, even with noise. > > > > This does not make any sense at all. The encoder.xx.index reports > > detecting a falling edge on the index (Z) input. it is reset every > > time it is read. Long true pulses mean it was triggered at least > > once every millisecond, ie. faster than the servo thread samples it. > > > > So, the encoder.xx.index is NOT looking at the STATE of the Z input, > > but whether a high-to-low transition occurred since the last time it > > was read. > > > > Jon > > > > > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > 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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
