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I develop a CAN-BUS receiver (logger) with an ESP32 and CAN-BUS transceiver.

The CAN-BUS transceiver modules which I found and bought have both 120 Ohm termination resistors. But the CAN-BUS to which I want to connect this (in a modern motorcycle) is already terminated on both ends. I want to connect my device to the CAN-BUS service connector (like an OBD2 ELM327 adapter).

Do I have to remove the resistors from these modules to make sure the bus is only terminated on both ends?

Or do I have to keep these resistors to make sure the transceiver modules work correctly?

Is it possible that the CAN-BUS or any device on the bus will be damaged if I don't remove the resistor because the load is too high?

I bought several of those modules and I can do "try and error" if necessary.

Here are two pictures of those modules: CJMCU-1051 CJMCU-230

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  • \$\begingroup\$ In theory you should remove the termination from the stub. In practice, CAN tends to not be very picky with extra termination on stubs, though this will depend on baudrate. At baudrates <500kbps the extra termination is unlikely to matter. It is more picky about missing termination. \$\endgroup\$ – Lundin Sep 20 at 13:45
  • \$\begingroup\$ Thanks, in my case it's 500kbps. Is it possible that the extra resistor creates problems because of the extra load (more current)? \$\endgroup\$ – Edgar Sep 21 at 0:17
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You need one resistor at each end of the bus.

Diagram of CAN-Bus

Image source: KMP Drivetrain Solutions - Practical tips: CAN-Bus

Every other resistor could be removed.

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As long as the (long) CAN Bus is terminated at both ends it should work providing the stub connecting your board to it is fairly short. So remove the termination from your board.

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