CAN troubles with Black Jaguars

[Levansic]

Our team had always used the Jaguar controllers in PWM mode, but this year we wanted to jump overto CANbus control. We thought we had done enough prep work, downloading firmware and getting BDC-COMM onto an old laptop with a serial port.

Our black jaguars flashed to the new firmware just fine, and all were given unique ID's. When we tried to update our beige jaguars, we hit a major snag. None of them were visible when hooked up to a single bridging black jaguar. We hooked up two black jaguars, and could not see any beyond the first, directly connected to the serial port.

We did web searches and scoured this forum. The most thrown-out solution to the same problem, as encountered by others were faulty terminators and faulty cables. After much wasted time trying to find non-existant faults in these components, we finally found the source of our problems.

In our case, all six of our black jaguars had faulty RJ-11 jacks (CAN - only), and two also had faulty RJ-12 jacks (Serial + CAN). Oddly, not a single one of our seven beige jaguars had a single faulty port. The problem is a minor manufacturing defect, where the sprung contactor wires in the jack are just not sprung enough. This causes contact to be lost with the slightest jostle of the cable.

We discovered this by noting that some connections could enable CAN communication, but lost communication If the cable was slightly disturbed. We had a lot of movement in the jacks. When we looked into the port, we found one of the center pair of contacts almost flat against the outer wall of the jack housing.

I carefully stretched these wires out with some needle pointed tweezers, and tested every port until I could maintain CAN communications, no matter how much I wiggled the cables. Now, all of our jaguars are maintaining communication over CAN