Terminator in Raspberry Pi CAN-shield
A CAN bus is meant to be an (electrically) straight line with a terminator at each end and nodes (at least two) attached along it. That means just two terminators.

If length and/or noise margin are not of concern, some stubs out to nodes can be added. As long as they’re short, they don’t hurt too much. One imperfect heuristic is to take twice the length of the stub away from the possible total length; a coarse approximation, but a starting point.

A node looks like a 10 kohm (or more) load on the bus. If you attach extra terminators, i.e. more than the required two, near the center of the bus, that adds a lot more load (about 100 times as much current), so it greatly reduces how many nodes you can attach to the bus. One extra probably will still work, but might not handle noise well. Two or more extra terminators (i.e. 4 total) are unlikely to work.

With three nodes close together, almost any wiring will work, so don’t worry about stub wiring too much. Just put two terminators on, one at each nominal end, and enjoy.







simulate this circuit &ndash; Schematic created using CircuitLab