Thread: CAN reliability
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Unread 12-12-2010, 15:15
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Omar Zrien
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Re: CAN reliability

New Firmware and plugin is available at http://www.crosstheroadelectronics.com/2CAN.htm

Marshall (or any one), have you observed any latencies issue with a 2CAN? I know you've done the extensive testing with the BlackJaguar.

One reproducible problem I can report is if I create a Robot app that drives throttle for several jaguars (say 1-10). Then only put one jaguar (id 1) on the CAN bus. When I do this the Jaguar does not drive at all (massive delays and timeout issues). Looking at the CAN bus it looks like the cRIO is attempting to reestablish tokenization with the other jags. When this happens the throttle CAN frames are not going out for Jaguar 1, which causes Jaguar 1 to timeout as well.

This tokenization that occurs to keep the Jaguars enabled seems to block the transmit requests from the user's code (CANJagar::sendmessage) if the Jag on the other side doesn't send it's ack with token response, presumably because cRIO internal logic is waiting on the response. Now this could happen because of an intermittent cable issue somewhere, or because a jaguar is left unplugged (deliberately or accidently) or because of software.
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