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Stepper motors keep shorting... but only on one computer

Hello All,
I recently switched computers and my EiBot stepper motors no longer work. However, they still work on the old computer. The old computer is a 32-bit Windows XP running LabVIEW 2009. The new computer is a 64-bit Windows 10 running LabVIEW 2015. My robot uses the EiBot Board connected to a single servo and 2 stepper motors. On both computers, the servo command works with no problem. However, on the new computer, when I tell the stepper to rotate through LabVIEW, the stepper motor makes a small noise and then stops moving. In addition, the servo motor button will no longer work after this has happened. I get a notification that the USB is no longer recognized and I have to unplug and replug in the power supply to the EiBot Board to make my computer recognize the USB again. This problem does not occur when using the old computer even though the only difference in the setup is that the USB is plugged into the old computer rather than the new one. I checked the code and it is sending the exact same commands regardless of the computer being used. I’m not really sure what could be causing this problem. It almost seems like I’m sending too much current through my Board, but why wouldn’t that be the case regardless of the computer used? I’ve tried decreasing the velocity of the motor, but that did not make a difference. I also tried switching out the power supply cord and the USB cable, but still no dice. Oh, in addition, I have operated the stepper motors individually using the manual tab of the eggbot extension on Inkscape. This works fine on the new computer so I know it is at least capable of powering a single stepper at a time. Any suggestions would be great!


  • Nothing in your description would suggest to me that there is any kind of "shorting" or overcurrent event going on. If there were, I'd expect it happen on either computer, and I would not expect resetting to make a difference.

    Unplugging the power supply is probably unnecessary in resetting; you can probably press the RST button to reset it just as effectively.

    If you can, I would suggest that you try running the two motors simultaneously from within Inkscape. If you can do that, it should rule out the possibility (which you seem to be suggesting) that the issue is that running both motors at once is causing the issue, as well as ruling out the possibility that the new computer itself is the issue.

    (If you were to find that running both motors at once causes a failure, then it may be an issue of voltage droop due to pulling too much power from the power supply, which would suggest that a higher-capacity power supply is needed. This seems very unlikely as a root cause since it was working on the other computer)

    What this sounds like is as though you have some kind of USB communications issue in LabView, one which is causing something to get mucked up. Amongst other possible causes, this could easily be due to the change in the LabView version. (I have encountered changes in device communication methods in other situations when changing versions of LabView.) It could also be the case that the new computer is simply faster, and that this is the issue. The EBB has a very limited queue for input commands and it may be necessary to add intentional delays between subsequent commands to ensure reliable communication. This, of course, depends a lot on the types of commands that you are using, and how you are using them.

  • Hi Windell,

    Thanks for your feedback! I was headed in the wrong direction until you replied. You were right about the issue not being related to an overcurrent. It turns out that there was a global variable in the code causing all of the problems. Thanks again!

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