Using a star configuation for Jaguars on CAN

[Bryscus]

Originally Posted by Dale

We went so far as to buy the best RJ10 crimpers we could and buying a RJ10-45 cable tester. We tested each cable before putting it on the robot wiggling around the wire while we were doing it. We still had problems.

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I love the way the daisy chain cleans up the control board, I just don't like having, in our case, 18 flaky connectors in that chain any one of which can bring down the whole robot.

Dale,

I'm not sure about untwisted pair phone cable, but for Ethernet there are two types of wire you can buy - stranded and solid core. In this case it is absolutely vital that one buys the correct plug for the wire type used. Patch cables (the ones used for repeated connections between two devices) are twisted pair cables and allow more bending cycles (with a slight reduction in performance electrically). Solid core cable is what you run in the wall for static use. Again, the correct plug type is absolutely necessary. Now you mentioned you used RJ-10 connectors. I need you to clarify something for me. Is your connector a 6 position 4 conductor connector (RJ-11) or a 4 position, 4 conductor connector? Since the receptacles themselves are 6 position 4 conductor receptacles, I would personally use nothing less than a 6P4C connector. We used 6P6C (RJ-12) for everything because it will work in any connection between devices that one could possibly need (also, the 6P6C cable we bought was easier to strip than the 6P4C). The 4P4C connector is a flimsy connector that is most commonly used for connecting the handset of a phone to its base unit (for any of you that still have analog wired phones with the curly wires).

I do not believe we had any issues with the physical CAN bus itself last year (not that we didn't have troubles with the differences between the PWM style and CAN style, design-wise).

So in summary:

If you decide to use the CAN bus again next year, I would use at least a 6P4C connector for connections between Jags. The 6P6C setup may make the cables more robust because there are 50% more wires connected mechanically. Also, be sure to use standard phone cable (which I believe is stranded). We bought a fairly inexpensive crimper - about $20 bucks - and it seemed to do the trick. We did not test our cables with a tester either.

Good luck and I hope my ramblings help someone.

- Bryce