PDP CAN Connection Problems

We’ve had no problems with the PDP until yesterday. We uploaded some code with incorrect CAN ids for our jags, which caused the code to crash immediately (fair enough), but it also caused the COMM and STAT lights on the PDP to start blinking red.

We shut the system down, fixed the code, and rebooted and reuploaded. Now the robot works fine, except that the lights on the PDP still are blinking red, which is unsettling.

We have fixed red-blinking-lights on the PDP before by clearing sticky faults in the RoboRIO’s WebDash, but now the PDP doesn’t even detect the PDP in the CAN chain, though it does detect the jags and the PCM.

Any thoughts?

There’s a lot to read in between the lines there…
-Wrong Jag Ids should not cause your code to “crash”. It just won’t drive motors.
-The Jags can’t cause the PDP to blink red. Unless the CAN cable is shorted/opened somewhere along the way.
-Clearing sticky faults will not stop the PDP from blinking red. If it’s blinking red then it’s not seeing any CAN traffic. If the PDP is blinking orange then it has sticky faults asserted.

A quick test would be to power off the robot and measure the DC resistence between CANH and CANL. It should be 60Ω.

So to start with something simple can you just connect two wires between the RIO’s CAN bus straight to the PDP? Just take two long wires, disconnect the CAN hardness from RIO and PDP (which is easy since it’s weidmuller connectors on both sides) and just connect the RIO straight to the PDP?
Then power cycle RIO and open a new browser to check the roboRIO web-based config. Remember it takes a few seconds after an inital startup for the CAN devices to populate, so refresh a few times after it first comes up.

We have 60Ω across our resistor, and we’ve tried connecting directly to the PDP but nothing shows up on the webdash.

Java will throw an exception from InitCANJaguar if you try to instantiate a Jaguar that is not on the bus and functioning, which will kill your program.

Ahh I see. No try-catches to handle that situation then.

If you’re still seeing red lights with straight connection to the RIO I would just contact [email protected] directly.