Potential DSC Damage

[BitTwiddler]

Originally Posted by slijin

As I can't find this specification on the USFIRST-provided spec sheet (or a confirmation through forum searches), I'm turning to the CD community for a definitive answer to this question: Is the ground on the GPIO pins of the DSC 12V tolerant? Alternatively, will plugging in a 12V signal to the power or ground pins on the GPIO damage the DSC?

The reason I ask is because we've been having issues with an apparent short to our frame, which induces sudden motion upon providing power to the robot, but the short point is unidentifiable, and we suspect the damage lies in the DSC.

The current situation is as follows: Closing the circuit breaker (giving power to the PDB) will, on occasion, incur forward motion in a number of motors that persists for a few seconds. I know for sure that the motors on PWMs 1-3 and 6-7 are moving forwards; 4 and 8-10 have no connections, and 5 may be doing so (but is unconfirmed). Later testing only saw motion in a subset of these motors (which is undetermined).

The backstory: The sensors (details later in the post) were wired with +12V and GND to a 20A PDB, a 1K pullup across the 5V and signal, and the signal wire was mistakenly plugged into both the +5V and GND (at two different points).

The one common factor that we have confirmed is that this phenomenon only occurs when the signal from our conveyor sensors is plugged into the DSC (on the signal pins). We are using Banner QS18VN6D sensors (the white signal line) for this purpose.

The camera and cRIO are isolated from the frame and we cannot identify any other potential shorting point.

We didn't get a chance tiday, but we plan to confirm tomorrow whether the point of failure is the DSC (if we can reproduce the issue) by cutting its power and unplugging the DB37. Until then, it would be great if someone could confirm our hypothesis.

Is the 5V indicator on the DSC still lit? I'm not sure you did any damage to the DSC by routing the signal line to either ground or the 5V pins. Worse case I see is if the output was at ground and you plugged it into the +5V pin in which case the on-board regulator would go into current limiting mode. Now if you had routed the 12V to the DIO or +5V pins then damage might occur. Be advised, the DIO input pin connects straight to the cRIO DIO module through the 37 pin cable.