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Unread 11-05-2012, 11:48
linuxboy linuxboy is offline
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AKA: Oliver Graff
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Re: Intermittent connection on field only

Quote:
Originally Posted by Al Skierkiewicz View Post
Oliver,
From what I understand, the resistors are an integral part of CAN signaling in addition to terminating the bus. With an intermittent resistor, CAN devices cannot signal when they want to transmit data to the bus.
Has anyone used a CAN splitter to any advantage?
The terminator is required by the CAN spec, but it is there to prevent "signal reflection" which messes things up, however it will operate, without it, albeit with a smaller number of devices on the bus, however, my understanding is that no terminator at the end of the bus leads to issues with the Jaguars at the beginning of the bus, and lacking a terminating resistor at the beginning of the bus leads to issues at the end of it.

I have seen pictures of CAN splitters (there is a discussion about them on here somewhere), but they need terminators on each branch, and I believe the more branches you have the shorter each cable must be. In terms of CAN not being something that should shut everything down, when it comes to error handling and timeouts it can, even if it shouldn't.

Quote:
Originally Posted by RyanN View Post
Trust me. I know that wasn't the issue. It also wasn't our issue at bayou because we got rid of everything on our robot besides motors and solenoids. All using PWM, relay, and solenoid outputs, no camera.

It's just a potential problem that can come up that isn't easily diagnosable. CAN errors shouldn't cause everything to shut down.
I wasn't saying that CAN could have caused the problem at Bayou for you guys, I was just responding to the testing you were doing with it. I really do hope that the root cause of what happened to you guys at Bayou is found, I'd love to hear it.

Last edited by linuxboy : 11-05-2012 at 11:52. Reason: Add stuff