Thanks for your response.
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Originally Posted by EricVanWyk
The short, conservative, answer is that this fault condition is not within spec, and further operation is not guaranteed. The GPIO signals are not intended for 12V operation in any configuration, the GPIO power and ground pins are intended as outputs only. Unfortunately, that isn't made clear in the documentation you linked to. I will try to include this information in the next revision.
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Good to know.
Quote:
Originally Posted by EricVanWyk
The longer answer is that "a few seconds of forward motion from multiple motors" has to be the weirdest symptom I've ever heard for a DSC fault. My best guess is that it is somehow generating a single PWM pulse. Here are the problems with that theory:
1) It should generate less than a second of torque before the motor controllers shut down again. Maybe inertia makes it look like several seconds?
2) The pulse length window is pretty short. It feels unlikely that a fault could accidentally create a valid signal.
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When it first surfaced*, it actually just
spun around. Unfortunately, I wasn't present to observe this occurrence, so I can't provide more details than are present in the video. Later on, the issue was indeed momentary twitching upon powering the robot that would terminate after a few seconds.
*When the issue first surfaced, we had two unresolved issues. 1) There was a case short through the camera (Axis 206). This issue has since been rectified. 2) When the circuit breaker was open (no power applied), but the battery connected, we could read 12V across the +12V from the battery and the chassis. However, I'm afraid that this wasn't the issue at fault, as a)we measured 12V across the chassis, not 5V, which is the nominal spec on the camera's power line and b) the issue persisted following removal of the camera.
Quote:
Originally Posted by EricVanWyk
Are you using Victors or Jaguars?
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We are using 6 Victors, with 2 Jaguars on CAN.
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Originally Posted by EricVanWyk
Do you have control of the motors after their initial jump?
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Yes, we do.
Quote:
Originally Posted by EricVanWyk
Have you tried swapping in a different DSC?
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That will be the second thing we'll be doing when we go in today (the first will be, if the issue remains reproduceable, disconnecting the DSC from all sourced power).
Quote:
Originally Posted by EricVanWyk
The NI9403's datasheet states that it can withstand up to +/-30V (with no impedance) on up to 8 channels. You likely applied +/-12V with 0-20 kOhms impedance to many of its channels.
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The chassis short was +12V, with 7 kOhms of impedance.
Quote:
Originally Posted by EricVanWyk
I can't guarantee that you did not damage this unit, but I suspect the DSC much more than the 9403.
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Hopefully we'll be able to provide more details after the DSC is switched out.