Duet Maestro Short to Ground



  • It has been maybe six months since I struggled with random short to ground issues with one of the first Duet Maestro boards and ultimately returning it to M3D. I saw there was some progress to a solution using an unofficial firmware. But has this come to some official resolution at this time? I would like to give Duet another shot.



  • @infamous_panda Not sure on the Duet Maestro. However I have two DuetWifi's and I love them! Have little to no issue with them and the documentation and support is awesome!


  • administrators

    The issue of spurious short-to-ground reports from the drivers when using them in stealthChop mode was resolved many weeks ago, in the 2.01 firmware release AFAIR. The reports are a known feature of the Trinamic drivers at high speeds, and the fix is to have them switch to spreadCycle mode above a certain speed. We've made the speed at which it does this configurable.



  • @dc42 That's good news. By "configurable" do you mean that this is something you expect will have different speeds for different setups? How would one go about determining this value?



  • @infamous_panda said in Duet Maestro Short to Ground:

    @dc42 That's good news. By "configurable" do you mean that this is something you expect will have different speeds for different setups? How would one go about determining this value?

    Hi. There - https://duet3d.dozuki.com/Wiki/Gcode#Section_M569_Set_motor_driver_direction_enable_polarity_and_step_pulse_timing


  • administrators

    @infamous_panda said in Duet Maestro Short to Ground:

    @dc42 That's good news. By "configurable" do you mean that this is something you expect will have different speeds for different setups? How would one go about determining this value?

    The firmware default is to switch at a very low speed, so that the drivers are in stealthChop at idle but switch to spreadCycle even at quite slow speeds. If this is too noisy, you can increase the threshold so that it changes over above your usual print speed but probably below your maximum travel speed. There is a slight jerk at changeover (this is a feature of the driver chip), so it's probably best to avoid the changeover happening during printing moves.



  • Almost ready to dive back in. Question:

    So previously when the short to ground error occurred. The board/software would turn off that motor/axis, but the others would continue to run indefinately. As you can imagine this can be catastrophic especially on a delta printer. Is it now possible to have a setting to stop or pause the print should this error occur?


  • administrators

    That's a good point, However, short-to-ground reports are rare, now that we've sorted out the issue with TMC2224 drivers giving false short-to-ground reports.



  • Is this functionality something that would be non trivial to implement?

    The biggest pain point when I was trying to diagnose this issue, was that I would have to watch and wait so I could shut down the printer as soon as it occurred or risk damage. This could be anywhere from 1 minute or well over an hour into a job.

    So the the issue is mostly mitigated but as you say there is an element of experimentation in balancing speed and noise to for each printer setup. Without some range of values on when stealth-chop is known to fail I don't think I could leave the ever leave the printer alone.


  • administrators

    It's not exactly trivial, but I will add it to the firmware work list. Pausing the print would not make sense in this situation, it would be necessary to stop the print and leave the print head exactly where it is.



  • Bit the bullet a week back and have gotten through maybe 10 hours of successful printing without the short to ground issue.

    Not going to mess around with Stealthchop/Spreadcycle for now since the machine runs quiet enough.

    Having some other trouble which I'll start a new thread over.


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