Can't figure out error short to ground with specific stepper

  • I am attempting to hook up an escap (now Portscap) P430 258 005 01 disc magnet stepper motor to Duet 2 Wifi V1.01 running 2.01(RTOS) (2018-07-26b2).

    I have 4 of these steppers and I have tried 2 of them so far with the same results. Wiring on drive 3 with 1B to B+, 1A to A+, 2A to A-, 2B to B- and I tried 1B to A+, 1A to B+, 2A to B-, 2B to A- . Nothing hooked up to the stepper shaft, allowing cold extrudes, trying to extrude 1mm at 5mm/s. I kept current low at 500ma, E1200 steps/mm, and E16 microstepping to start with. First attempt motor will shake but shaft not turn then go into holding low whine and then quiet. Second attempt causes "Driver 3: short-to-ground standstill, SG min/max 0/1023". Shutting down then plugging in a standard NEMA 17 and powering back up and it works fine.

    The windings are wired in parallel from the manufacture and I got them second hand from an unknown OEM application. They look brand new and the windings ohm out correctly*, and no unexpected leakage between them or the case at 500V with a megger.

    *They ohm consistent at 1.7 in parallel instead of 2.5 as the spec sheet shows I assume because the OEM asked for different than standard windings.

    I would like to try one of these for a highly geared Nimble (30/1 IIRC) extruder due to their low rotor inertia and the high speed pull in and pull out from the torque/speed graph.

    Am I miss-wiring them or am I missing something that would make them incompatible with the Duet TMC2660?

    Here are the links to the manufacture web page and the spec's:

    Thank you in advance if you take the time to look and school me.

  • administrators

    The symptom sounds like the motors are incorrectly wired to the driver. You should have e.g. wires 1+5 connected to the pin at one end of the Duet motor connector, 2+6 connected to the next pin, 3+7 connected to the next one, and 4+8 connected to the last one.

  • As an experiment I used a 1.5V battery to verify that the following full step and wave drive sequences worked and they did


  • Posted that before I saw the reply so I'll check out and try what you said DC42

  • Awesome, that makes it spin. Guess I had a "duh" moment. Thanks a million David.

  • One question though if you don't mind. Why would I get an error short to ground when nothing was shorted? Magnetic fields opposing?

  • administrators

    If you wired two coils in anti-parallel then the magnetic fields would oppose and the net result is near zero inductance. This would result in a rapid rise in current, because only the coil resistance would limit it.

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