Closed loop stepper motors on duet2

  • Hello, I occasionally read on the forum. Now I have a question and Ryan from Ooznest told me to place it here.

    I try to connect closed loop stepper motors (2phase) to a duet2 with an expansion breakout board. Before I had normal stepper motors with external drivers on the duet.
    When I use the jog commands (G0) with the buttons it works. When I use a other command,like homing (G1), it goes wrong. Stuttering movements and the distance is no longer correct. The distance is ok when i use the buttons.

    If i set the closed loop running off with a switch, same result.
    The strange thing is that the driver does not give an alarm for the missed steps. So the driver does not see the missed steps.
    When I block the motor, the driver go in alarm because of missed steps, so that works.

    I tested with a 3phase motor/driver, also closed loop and this works fine.
    I tested the 2phase motor with a normal driver and this works also fine. So the problem is the driver or the settings?

    G1 command with higher speed works.
    So it's somewhere a setting, but which one? I have no idea.
    The seller gave me software to program the driver. Here I can see that if I give 5000 pulses with a speed of 15000,
    the driver also gives 5000 pulses. But when I give 5000 pulses at speed 1500, then only 800 pulses are counted.
    So only higher speed as 12000 works.

    I'm using following motor and drivers:
    2phase LC57H2100 from Lichuan
    LCDA257S driver from Lichuan
    Shenzhen Xinli Chuan Electric Co., Ltd.
    bought on Aliexpress.

    Motor encoder resolution is 1000 (PPR)
    Step angle 1.8°

    Does anybody have experience with this? Or an idea how to solve this?

    Sorry for my english.


  • administrators

    Most external drivers need slower step pulse timings than RRF provides by default. Consult the stepper driver manual for details, and use the M569 T parameter to configure them in RRF.

  • Does that mean in that i must set a T parameter with higher numbers? Any idea how high? I'm a newbee in this material

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