On Tuesday 05 May 2020 18:30:42 Dan Henderson wrote: > Gene, how do I speed up the servo loop to test your theory? I’ll try > that before I perform surgery on the BOB. I also have another BOB I > can try, but it requires 12-24v power in order to enable its inputs. > I meant slow the motor to see if it stabilizes, at say 75 rpm. zero everthing at the pid except some FF0.
Bobs nearly all have opto inputs, the only exception I know of is a long discontinued cncv4pc C1G rev 4 board. Great board, but $80someting back in the day. Many even have opto outputs. Mesa cards generally have neither so they can work at 100x higher frequencies. The SainSmart bob has no opto's in its outputs, but does have them in its 5 inputs. When its being used with a Mesa 5i25, its totally comfortable with 200+ kilohertz signals from a high res encoder, once those opto's are bypassed. Without the bypass it only worked up to about 375 rpm at the motor, then the opto's failed and the pid and motor went wide open. > On Tue, May 5, 2020 at 5:07 PM Gene Heskett <ghesk...@shentel.net> wrote: > > On Tuesday 05 May 2020 17:48:01 Dan Henderson wrote: > > > I have a PMDC motor I’ve scavenged along with the MC-2100 motor > > > control from a treadmill rated for 1.5 hp @ 90 volts. I’ve been > > > testing it with LinuxCNC v2.7.15 in a mock-up environment I built > > > for testing. I’m able to control the spindle speed via PWM pulses > > > to the controller (HD2 pin 4). M3 S500 will get me somewhere > > > between 520 and 580 rpm. You can hear the motor whine fluctuating > > > with the RPM. I’ve also installed a CUI ATM 10 encoder on the back > > > and seem to have it working with both an index and phase A signal. > > > I have the jumpers on it set to 200 PPR but it can go all the way > > > to 2048. I’m using a cheap china 5 axis BOB connected via parallel > > > cable. > > > > > > Does anybody have any idea why I’m get so much flux on the rpm? > > > Surely this isn’t normal? I know enough about the HAL to be > > > dangerous. Is there some things I can check to smooth this out? > > > Thanks. > > > > If using a software encoder, as opposed to a mesa card, the time > > delay between samples at the 1 kilohertz servo loop can do odd > > things. Among others, the lag in the input opto-isolators of that > > bob can even cause missed pulses from the encoder to the software. > > Try a much lower speed to see if it stabilizes. If handy with a > > soldering iron, bypassing those opto's can help, a lot. > > > > > _______________________________________________ > > > 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 > > _______________________________________________ > 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
