Sorry for my sloppy terminology. My servo has 3 input pins,
enable/step/dir. If enable is asserted it holds the position, otherwise
the shaft can be turned freely. Which is the behaviour I am looking for.
I want the spindle to not be engaged for manual tool changes, touch offs
and such. But then I want the spindle to hold its position for
tightening the drawbar and things like that, kinda like a poor
man's version of a spindle lock.

Unfortunately the pin motion.spindle-on does not assert just because I
issue a M3 or M4 command, it also requires S to be non 0. This is the
behaviour I see on the oscilloscope which is not good because I need
the enable pin of the servo to be asserted for it to hold its position.

Hope this makes more sense.


On Sat, 18 Jul 2020 17:11:20 -0400
justin White <[email protected]> wrote:

> motion.spindle-on is a pin, "spindle-enable" is your signal.
> 
> You don't need to trip the "....stepgen.NN.enable" pin to have a
> step/direction servo hold position, you just stop sending it pulses
> which "m3 s0" should do with no further interaction. disabling the
> stepgen does not cause the servo to go limp because the drive should
> be setup in position mode and stepgen only sends steps to alter
> position. Holding a position is always assumed in position mode
> servos.
> 
> What may be happening that you didn't mention is that when you enter
> M3 S0 it trips the motion.spindle-on pin and since it is connected to
> the stepgen.enable pin it may be causing your drive to fault out. If
> your spindle is at speed and you immediately disable the stepgen
> there is no (de)accelleration curve and your drive may fault.
> 
> Otherwise you can connect the stepgen.enable to
> "motion.motion-enabled" or motion.power-on(or something like that)
> depending on how you want it to work.
> 
> On Sat, Jul 18, 2020 at 12:08 PM markus <[email protected]> wrote:
> 
> > I replaced my spindle with a servo motor and was hoping to use "M3
> > S0" to hold the current position of the spindle. The signal
> > "motion.spindle-on" however only asserts if S>0, when S==0 the
> > signal is not asserted.
> >
> > Is there a different signal I could use? Should this work?
> >
> > Thanks in advance,
> > Markus
> >
> > ...
> > # ################
> > # Spindle [3]
> > # ################
> >
> > newsig spindle-enable bit
> > sets spindle-enable FALSE
> >
> > # spindle wiring
> > net spindle-enable              <= motion.spindle-on
> > net spindle-enable              => bb_gpio.p8.out-37
> > net spindle-enable              => hpg.stepgen.03.enable
> > net spindle-velocity            <= motion.spindle-speed-out-rps
> > net spindle-velocity            => hpg.stepgen.03.velocity-cmd
> >
> > setp hpg.stepgen.03.control-type     1
> > setp hpg.stepgen.03.steppin        833
> > setp hpg.stepgen.03.dirpin         835
> >
> > # timing parameters
> > setp hpg.stepgen.03.dirsetup        [SPINDLE]DIRSETUP
> > setp hpg.stepgen.03.dirhold         [SPINDLE]DIRHOLD
> >
> > setp hpg.stepgen.03.steplen         [SPINDLE]STEPLEN
> > setp hpg.stepgen.03.stepspace       [SPINDLE]STEPSPACE
> >
> > setp hpg.stepgen.03.position-scale  [SPINDLE]SCALE
> >
> > setp hpg.stepgen.03.maxvel          [SPINDLE]STEPGEN_MAX_VEL
> > setp hpg.stepgen.03.maxaccel        [SPINDLE]STEPGEN_MAX_ACC
> >
> > --
> > website: http://www.machinekit.io blog: http://blog.machinekit.io
> > github: https://github.com/machinekit
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> > .
> >  

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