Looking for a CAN bus "hub"

I attended the Tallahassee Regional last weekend and I saw a PCB that had multiple terminal blocks that the CAN connected to so if anything were to happen in the chain, everything else still works. I spoke with a member from 7431 about it.

I forgot to ask him about where he bought it from or what it was called. I haven’t seen anything glaringly similar to it, IIRC it had 6 connections with green terminal blocks and a black pcb.

We use these:

I thought they were no longer being made. But it’s on their site.

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I can’t speak for usability or reliability but this is a board ive seen mentioned in the past.

https://www.playingwithfusion.com/productview.php?pdid=103

THESE ARE IT

Thank you!!

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Maybe I just don’t fully understand CAN, but even if one of the segments has an issue and something comes plugged or broken won’t that still break the bus and cause reflections?

The idea here is that everything is wired in parallels on the Hub and because every CAN device has its own ID it shouldn’t cause interference.

Motor 0 will see Motor 3’s command but wont act because it hasn’t been called upon.

In this setup, each device would be a small branch so wouldn’t require their own terminating resistors. The resistor would go in this block if this is the end or would go after the block if there are more devices.

If there’s a long run of can wire with a terminating resistor after this block and that becomes unplugged from the block then yes, the can bus would still fail.

We custom made our own Pcb for this purpose

We did our own thing but the idea is similar. The terminal block pairs at the ends are for the main daisy-chained CAN bus going around the robot. The middle terminal block pairs are for stub connections, like swerve modules that need 3 CAN connections.

As long as the stubs are limited to less than a foot, it all works fine.

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We use a similar custom one but at this point, I’d rather use something like https://a.co/d/hdat9ks because lever nuts are better than every other kind of connector imo.

You’re welcome to use this design. It distributes CAN and power and is intended for swerve modules using two motors and a CANcoder.

GitHub link

I second the Playing with Fusion CAN Drop boards. 3468 used them for our swerve modules this year and they were great.

I have also considered these boards on Amazon, but can’t personally attest to if they are suitable for CAN in practice.
https://www.amazon.com/dp/B091F9CGQF/

https://www.amazon.com/dp/B08TBXQ7H6/

Also, we use ferrules on the wires going into the block. No messing with random strands of yellow touching a random strand from green.

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