pic: cRIO CAN Jag

[DonRotolo]

Originally Posted by squirrel

The only thing that worries me is all those RJ45 connectors in series

Point of order: The 4-pole RJ series is an RJ-10*. Doesn't affect any other statements though.

Originally Posted by squirrel

the CAN bus is a daisy chain. Any one poor connection can kill the rest of the chain.

Nope, the CAN Bus is a parallel protocol, without repeaters or gateways (generally). I would fully expect an unbroken signal path from input to output; the CAN Bus controller would hang off the side of those conductors, not in series with them.

CAN doesn't work well in series or daisy-chain, and that's not the way it is supposed to be used.

It works more like a Radio channel, where everyone hears everyone else, and indeed everyone must hear everyone else (including yourself) in order for the bitwise arbitration to work. (That is the method used to ensure that messages don't collide on a CAN Bus).

A 1 Mb/s CAN bus is a Class A bus, and definitely requires terminating resistors. Their optimal value depends partly on the chips being used, and mostly on the expected medium (type of wires).

There are many CAN Bus resources on the web, however for FIRST I don't think a detailed understanding of the physical layer will be necessary to use it at the application level.

*Also RJ-9 and RJ22 - I cannot tell from LM's data sheets which specific implementation of the 4p4c standard they have. I suspect they did it to take advantage of inexpensive (unreliable?) telephone handset cables.