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In my design - rugged computer - I have connected the digital gnd to the isolated CANbus gnd by mistake.

  1. Does the CANbus standard state that it has to be isolated?

  2. Can that connection harm the CANbus?

  3. Can this connection harm the computer?

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  • \$\begingroup\$ First of all, do you have an isolated CAN bus or is the CAN bus ground just the signal ground? What's the hardware between your CAN controller and the CAN High/Low lines? \$\endgroup\$
    – Lundin
    Mar 13, 2019 at 8:33
  • \$\begingroup\$ Next, is this rugged computer stand alone or connected to mains? Same question regarding the connected CAN devices. \$\endgroup\$
    – Huisman
    Mar 13, 2019 at 8:38
  • \$\begingroup\$ 1. Yes the CANbus is isolated. I have pulled out by mistake the digital ground of the board to the CANbus connector instead of the isolated CANbus ground. \$\endgroup\$ Mar 13, 2019 at 9:04
  • \$\begingroup\$ 2. The rugged computer is isolated from the mains. It has its own isolated dc to dc. \$\endgroup\$ Mar 13, 2019 at 9:06

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  1. No, it is optional. Some application-level standards like DeviceNet require galvanic isolation.

  2. If there are various ground potential differences in the system, you may experience communication problems and error frames. Galvanic isolation is there to counter this. Nothing will break physically.

  3. Not if the system ground is sound.

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