Quote:
Originally Posted by jimbo493
CAN is run in parallel, so you could easily just twist two wires together and insert them into the crimp or something like that. An inconvenience, but it still works as it should. the greens and the yellows are commoned on every device out there.
EDIT: Star topology is not recommended, discussed here, and here
Yes it may work, but you are more likely to run into signal quality issues, due to the loss of twisting and long runs, besides, I'm not sure I see the real benefit, you need a pair of wires for every device on the bot going back to a central location, rather than short links from device to device.
Basically, dont do star, and you can make it work, but id recommend the weidmueller connectors if they do a revision if the board, even if it adds to the cost.
That red cable looks like a Y cable to me, I wonder if thats what its for, however, I see an issue of the wrong colors for CAN wiring(required in the rules, usual disclaimer about 2017 being different...), and it doesn't look twisted |
I did see those threads previously but to be honest we never had any issues wiring our CAN using Star. Aside from some poor crimping early on the system ran flawlessly throughout the season this past year.
We opted for this method because we got tired of having a single loose link between two controllers or a dead/unpowered controller disable the entire robot for a match, while Star doesn't guarantee redundancy (as a connection loss at the controller will still disable everything), it's removes a LOT of points of failure and reduces the impact of most failures if/when they do occur. I would much rather loose one of my 6 drive motors for a match than the entire robot.
We didn't have any issues with cable lengths either, but we did keep most (though not all) of our CAN devices close to the central hub (made mounting easier anyways) so long wires weren't necessary. We also did not add any terminating resistors beyond what's already part of the RoboRIO and PDP.
There is also plenty of searchable documentation that supports Star Topology (as well as one called "Ring", which looked interesting) as an option for CAN systems (different environments, granted, but same architecture regardless).