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I know that for a thumb rule, it is possible to have a length of CAN Bus network with: Speed [Mbps] * Length[meter] < 50 . i.e., with 0.5Mbps, it is possible; source.

But, is it possible to have the CAN Bus network cable as a T shape? i.e., to split the cable in the middle to another cable? Like in the following diagram?

T shape CAN network

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    \$\begingroup\$ Is it possible? Sure you can build that. But should you? No. Will it work? Who knows. What you describe is against the best practices how to make a good bus. It will not be within the requirements for a linear bus with maximum stub length and is basically not a linear bus but a star topology. \$\endgroup\$
    – Justme
    Commented Jul 7, 2021 at 5:37
  • \$\begingroup\$ Hey @Justme, so I have to use some kind of bridge to make this topology to work? \$\endgroup\$
    – oak
    Commented Jul 7, 2021 at 6:03
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    \$\begingroup\$ Yes you either need a gateway or a smarter way to route the cables. \$\endgroup\$
    – Lundin
    Commented Jul 7, 2021 at 6:17
  • \$\begingroup\$ ha, you mean that instead of bridge we can route the cable back and forward into the "T" and consider this as linear? \$\endgroup\$
    – oak
    Commented Jul 7, 2021 at 6:30

2 Answers 2

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Take note of what is said in the document you linked: -

enter image description here

  • Maximum unterminated stub length is 0.3 metres
  • Terminations are required at both ends of the cable

This also means that you must have two (both) cable terminations (not more and not less). This means very short stubs or, if that isn't possible, then you loop the cable in and out of where you want it to route.

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Following @justme and @Lundin, two possible solutions:

  1. Separate into two buses. One Horizontal bus and the other Vertical Bus. Then have a CAN bridge between them.
  2. Instead of splitting into two, if the length allows, it is possible to get the "BUS" as a "snake". Starting from the left up to to middle then going up and down, then going to the right. This keeps the BUS with linear Topology.

See image: "Snake" instead of "T" toplogy

#EDIT: Note that image line is the network itself. i.e two physical lines, high and low.

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    \$\begingroup\$ Yes, this will work just fine. Though please keep in mind that you won't be able to use the highest baudrates for a bus this long. electronics.stackexchange.com/questions/436117/… \$\endgroup\$
    – Lundin
    Commented Jul 7, 2021 at 11:10
  • \$\begingroup\$ thanks, we are aim for 500Kbps. It looks like we are ok up to 100m \$\endgroup\$
    – oak
    Commented Jul 7, 2021 at 11:49

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