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Unread 06-02-2010, 17:27
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Our CAN Tale of Woe

The moral of our story is - get the right connectors and the right crimpers.

We spent nearly three weeks trying to get the computer to connect to the CAN network.

On our first pass we purchased standard off the shelf 4 wire telephone cables and connectors. Wire everything up and of course got nothing.

I really don't like that the CAN cables are non-standard telephone cables. I also dislike that we have to make our own cables. This is the primary cause of our problems.

After re-reading the data sheets we purchased a few 6-wire connectors and made new cables for the serial-to-CAN cable. We'll worry about the others later. It still didn't work. Turns out the crimper we purchased is a 4-wire crimper.

We found an RJ-45 crimper and tried that. It looked like it worked, but testing the cable showed that one wire (white) didn't connect properly. The RJ-45 crimper is 8-wires. The outside wires could not be crimped properly due to the shape of the connector.

So, back to the store to find a proper 6-wire crimper. The 6-wire crimper has finally worked for us. We have now re-made all of the cables, flashed all of the Jaguars, and assigned them addresses. Now for some LabView testing with the CAN VIs.

We have one Black Jaguar that is still not responding. I'm glad we got a spare. (Although now we have no spare. )

So the moral of this story is to get the right connectors and the right crimpers. The cables are the key to successful use of CAN.

I like that CAN is a positive locking network. I dislike that it requires non-standard cables to operate. Success would have been much more satisfying if we could just use off-the-shelf cables.

We're off to do more robot testing.
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Duane Murphy
Mentor - Software
Vanden Vikings FIRST Team 701
http://www.vandenrobotics.com
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