Recently, our team wired up a board with a few talon SRX’s (using CAN) to test a few encoders, though they aren’t working exactly right. I tried a few different configurations of motor controllers and recorded the results:
RoboRIO - PDP: PDP light is red, doesn’t connect
RoboRIO- Motor Controller A - PDP: MCA light alternates red, PDP light is orange, and the PDP shows up in the web based config
RoboRIO- MCB - PDP: MCB works, PDP light is red and doesn’t show up in config
RoboRIO- MCB(CAN wiring reversed) - PDP: MCB alternates orange and PDP flashes orange, but neither show up in the web config
RIO-MCA-MCB(original CAN wiring)-PDP: MCB works and shows up, MCA alternates red and PDP flashes red (neither show up).
RIO-MCA-MCB(reversed CAN)-PDP: MCB and the PDP both work, though MCA still alternates red.
RIO-MCB(original CAN) - MCA - PDP: both MCB and PDP are orange, but neither show up in config; MCA is red.
RIO-MCB(reversed) - MCA - PDP: both MCB and PDP work, MCA is red.
Even though it shouldn’t matter what direction the CAN wiring is in, it somehow does. Also, MCB and the PDP shouldn’t be affected by MCA (but of course they are). Additionally, order shouldn’t matter, but it affects the motor controllers.
What exactly do you mean it shouldn’t matter what direction the can wiring is in? If you mean it doesn’t matter if you connect green-green and yellow-yellow, I’m pretty sure you’re wrong.
Anyways, direct connection from the RoboRIO to the PDP really should work. Maybe you have a bad termination resistor. Power everything off and disconnect everything, and do a resistance check between green-yellow on the RoboRIO and the PDP. You should get 120 ohms in both locations.
No, I’m not switching green and yellow. By reversed, I mean that the SRX has 2 pairs of CAN wires. The first time, one pair was connected to the RIO and other pair was connected to the PDP. Reversed means the wire originally connected to the PDP is now connected to the RIO and vice-versa.
MC2 alternates yellow when it’s disabled, like it’s supposed to. When it’s run, the light changes color/blinking with speed (and it drives a motor just fine).
MC1 slternates red, so it’s either not connecting or their is a fault. Not connected doesn’t make sense because the CAN signal can pass through it. So I’m assuming there’s something wrong with MC1 itself.
I am from team 1389 and we kind of ran into the same sort of problem. We had trouble getting all of the Talon’s configured when they were wired up in CAN. What we found that worked was that when we would restart the roboRio everything, including the PDP, would blink correctly. I don’t know if this is any help but I think it might be worth a try.
One other thought is to try reversing the yellow/green pair on the suspect Talon. Maybe the Talon has the wires internally placed in reverse, meaning the yellow-is-actually-green-and-vice-versa. That could explain why everything works except that one Talon.