Using CAN in a star configuration

[jee7s]

Originally Posted by JefferMC

I would think the reason someone would want to run a star topology vs. a single end-to-end would be a desire to retain some control in the event of a failure of a single point of the CAN wiring.

With a daisy chain arrangement with end terminators, the CAN bus cannot survive any physical failure at any point.

With a star arrangement, e.g. with discrete PWM cables, any single PWM cable can be lost and not affect the ability to control any other PWM.

I'm not saying it is possible to run CAN in a star topology. But I observe the move of Ethernet from a single coax bus arrangement with end termination to the current star topology and one of the reasons behind it is robustness.

Keep in mind that ethernet has separate transceivers for every port. You can conceptually do the same with CAN, but most controllers have 1 or 2 CAN ports.

CAN really isn't all that fragile. It's used in automobiles, airplanes, automation, etc. It just takes some care during the wiring to make sure you have a bus that is intact and reliable. I would say that this new approach to CAN adopted by FIRST and CTRE using twisted pairs is much more reliable than the 6P6C version we had with the black jaguar. My experience with the old method was that the connectors were the most likely point of failure. Sometimes it was because they weren't made properly, some times it was because the connector was abused. But, with twisted pairs, if you take your time to get good solid connections and keep your colors straight, I don't think reliability is that much of a concern.