CAN reliability

[Mike Copioli]

Originally Posted by jhersh

The 2CAN plugin is another place where performance needs to be considered (but has not yet been addressed... support from CTRE is needed).

A new plugin and firmware version for the 2CAN will be released shortly. Joe you should be hearing from Omar soon regarding this if not already. I believe he has some CAN traffic snap shots that you may find helpful.

[jhersh]

Originally Posted by Mike Copioli

A new plugin and firmware version for the 2CAN will be released shortly. Joe you should be hearing from Omar soon regarding this if not already. I believe he has some CAN traffic snap shots that you may find helpful.

Sounds great... Thanks Mike!

[ozrien]

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.

[Mike Copioli]

Also note that there are now two different versions of the 2CAN firmware. Please be sure to download the correct version based on your application. A seperate link to a zip containing the plugin and the 2CAN firmware has been added under the Downloads for FIRST section at the bottom of the page.

[kamocat]

Originally Posted by ozrien

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

I have not tested with 2CAN.
I know I was originally complaining about the low throughput of serial port. (The 2009 Beta threads are gone now, or I would link to it.) However, the 2CAN wasn't released until January, by which time I was busy with the new season. By the time I was purchasing more Jaguars to make a test robot in late spring, the Black Jaguars were the only ones available.
And so, having some of the capabilities of CAN with almost no increase in cost, I couldn't rationalize buying a 2CAN.
That's not to say I wouldn't like one.