Travel moves are not straight. Is this by design?

[janbbeck]

@dc42 No more crashes. But I still have the staircase behavior. It has only happened on travel moves, but I don't know if that is a coincidence with them being faster and longer moves. Is there any easy way of finding out whether the Duet is sending the pulses out as bunches?

[dc42]

Can you check your MaxReps fixture again after a few travel moves?

[janbbeck]

@dc42 maxreps is typically this now:
MaxReps: 4, StepErrors: 0, LaErrors: 0, FreeDm: 231, MinFreeDm 120, MaxWait: 721129289ms, Underruns: 0, 0

[dc42]

That sounds OK. It looks like at worst, when some interrupt (probably a tick interrupt) occurs 3 pulses become overdue, so it sends a bunch of 4 pulses when the interrupt completes. Hence MaxReps = 4. This will probably happen one per millisecond.

[janbbeck]

@dc42 Ok, I take that to mean that I should look at the servo drive causing the behavior, right?

[dc42]

@janbbeck said in Travel moves are not straight. Is this by design?:

@dc42 Ok, I take that to mean that I should look at the servo drive causing the behavior, right?

Yes. If you use an oscilloscope to look at the step pulses, I am sure you will find they are regular. If they were not, then normal stepper motors would show the same problem. Even when step pulses for more than one motor become overdue, RRF continues to serve the motors evenly, except in extremely old firmware versions.

[janbbeck]

@dc42 I will replace the servo drive with one from a different manufacturer. Thank you for your time and help!