Stepper Motor Moving in the Wrong Direction

  • Hello,

    A stepper connected to an external drive connected to a Duet WiFi using RRF 3.01 moves randomly in the wrong direction. It has nothing to do with the M569 command, as it is happening at random as I push the button to move forward in the DWC and it goes in the opposite direction. Could it be noise, a hardware problem, or something to do with RRF3.01?

    Thanks in advance!

  • @dieguito sounds as if the external drive gets false direction commands sometimes. This can be a wrong time setting and a wrong voltage. Can you tell which external driver you have and the config setting for the drive, and which solution you use (Duex, Extension board, pin connector)? And how did you wire (ground connected, separate PSU etc)?

  • @JoergS5

    • the driver is the Leadshine D-508: link text
    • the config setting is:
    M584 X5								; set drive mapping
    M569 P5 S1 R1 T50:50:100:0  				; Drive 5 goes upwards
    • the duet connect to the driver/stepper via a Duet Expansion Breakout Board: link text

    • the duet and the driver use different PSU's with a common DC ground

    Thanks in advance for your time!

  • @dieguito you should set the fourth value to e.g. 5
    This is the direction hold time and was often the reason for errors in other threads.
    The other values are probably too high, but please test the fourth value first.

  • @JoergS5 This didn't solve the problem. Do you have any other advice? I used

    M569 P5 S1 R1 T50:50:100:5  				; Drive 5 goes upwards


  • @dieguito no idea, only that the first three parameters are too high. According to datasheet pulse width is 2.5 us (microsecond), so 50 is very high. Depending on the microstepping setting, it may not be sufficient. 50 us means 20 kHz maximum rate. How is your microstepping setting and which is your fastest rotation? Then you can calculate if the limit is reached (e.g. 200 step stepper, 16 microstepping, 7 rotations per second => 22400 steps per second => loosing steps). Direction setup time (3. parameter) is even slower, 0.1 ms means 10 kHz maximum.

    But the driver needs to have low signals between the stepper signals plus direction change, so maximum may be 5 to 10 khz. This is probably reached with 200 * 16 * 2 with 20 pulley 80 mm/s already.

  • @JoergS5 I troubleshooted this to be an intermittent ferrule connection. Thanks for all the help!

  • @dieguito nice that you found the solution and told me. Thanks!

    My impression is that I have to add checking for connection problems and electrical interference to my first-to-check list, when endstops, BLtouch etc. don't function correctly.

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