On Monday 20 July 2020 20:30:30 Jon Elson wrote: > On 07/20/2020 07:04 PM, Gene Heskett wrote: > > I think I'd drag out one of my 100+ MHZ scopes and look for noise of > > the type one might get from lack of a single point ground. > > Right. if the indexres test of the diagnostics shows the > position resetting multiple times/rev > (may only happen when spindle drive is on) then there is > noise on the Z. The A and B have digital filtering that > only accepts valid state transitions of the quadrature wave, > that hides a lot of really nasty garbage that some systems > have. There is no way to digital filter the index pulse, it > is edge-triggered, and a 10 ns pulse could trigger it. > > But, noise on the index will only affect the place where the > spindle sync motion starts. Once the spindle encoder senses > an index pulse, then everything is counted from there. So, > a noisy index pulse should NOT cause the Z axis to behave as > the videos show. OHH, wait a minute! One thing that COULD > cause this behavior is if the move exceeded the Z soft > limits. Z would freeze at the most extended part, and then > pull back when the spindle count brought the position back > within the soft limits. That's exactly what it did in the > first video. > > So, Matt should check what his Z soft limits are set to in > the .ini file, and then home the axis so > it won't be exceeding the soft limits.
I've not encountered that particular symptom, so didn'tthink of it, but you obviously have. > Having just spent about 3 weeks solving a ground loop issue > on a PWM servo system remotely, they > can cause an amazing array of crazy symptoms. Having the > user shorten up all the wiring fixed it. Interesting. I wonder if he accidently fixed an unwanted ground, or made a bad one good doing it? Murphy is alive and well despite our reward funds. > Jon > > > _______________________________________________ > 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
