On Wednesday 08 April 2020 22:30:55 John Dammeyer wrote: > > From: Leonardo Marsaglia [mailto:[email protected]] > > > > > BTW, Here's a link to the video that shows how I screwed up > > > thinking it was in position mode and was losing position with > > > higher velocities. https://youtu.be/cx-kAqdwceU > > > > > > When really it was running in velocity mode. > > > > So if I understand correctly, these drives have the option of > > driving them in velocity mode but with the speed reference being > > step + dir right? > > Yes. The only reason I have the spindle motor configured as 0-10V + > DIR is that using a single parallel port or 7i92H with LinuxCNC means > I only have PWM available on one of the pins. Under MACH3 I can > select from one of the config screens (no text files to edit) whether > I want the two pins to be STEP/DIR or PWM/DIR. > > So for now to be able to use the dual boot I'm stuck with the PWM to > 10V. But really for what I'm doing I don't really care. In the future > if once I wire up the second port I can use another StepGen on the > 7i92H instead of the PWM and then switch the drive over to steps to > create velocity. With a 2500 line encoder x 4 that's 10000 steps per > rev. The motor is rated at 3000 RPM or 50 RPS which means 50 x 10000 > = 500kHz.
Which is well beyond the range of most opto isolators including the ones in the stepper driver amplifier, and also well beyond the range of the optos in the average bob. Expecting anything resembling 0-10 volt control to act like that style is but a dream w/o bypassing the opto's leading to a hardware encoder. Removing and bypassing those in your BoB can be done but shouldn't be tried unless your soldering skills are good enough to tackle that with confidence, and is not something this C.E.T. can teach in an email msg. Dropping the pwm frequency to the 1 khz servo thread range can help with some hardware. > The drive can also multiply the step inputs with a n/d scale factor to > reduce the number of steps required relative to encoder pulses. The > encoder outputs mirrored onto the connector can also be scaled by an > n/d pair to reduce the encoder pulse output load on the PC. > > John > > > The Yaskawa drive I have in the Mazak for the spindle offers that > > possibility and I'm going to use it that way to simplify things with > > the boards I'm using. > > _______________________________________________ > Emc-users mailing list > [email protected] > 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
