2
\$\begingroup\$

I have 6 nodes that I want to connect on the same CAN Bus. All the nodes are installed in the same 19" rack, so each segment will be less than 2 ft (0.6 m). The CAN Bus connection on all the nodes is on a terminal block with screw terminals.

The CAN Bus speed is 50kHz. The cable used will be twisted pair. The nodes at each end will be terminated with 120 Ohm resistors.

Wiring

All documentation I have ever seen for CAN Bus shows the use of drop cables, but I would like to daisy chain the CAN Bus like it is shown in the above drawing.

I would like to know if anyone has any experience in doing the connection this way?

(This is for a SCADA system. 5 of the nodes are EtherCAN modules)

\$\endgroup\$
1
  • 2
    \$\begingroup\$ Various CAN devices are even intended for this exact use case, by having two sets of CAN screw terminals that are directly bridged internally, so that you can easily wire "incoming" and "outgoing" lines. At 50kHz and a few meters, the bus topology probably hardly matters at all and you can do almost anything... \$\endgroup\$ – Erlkoenig Jun 18 '20 at 4:51
4
\$\begingroup\$

The way your diagram is laid out this is exactly the same (electrically) as using drops at each node. Essentially, you need all of the CANL signals to be in parallel and the same for CANH. Since you are running the CAN backbone to each node with what is basically a very short drop you should be fine.

A daisy chain configuration would have a CAN input and a CAN output on each individual module. This would involve breaking the bus at each module (with 2 transceivers each) or linking them together internally which would be the same as a drop.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.