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SN65HVD230: CAN isolator (from CAN to CAN) having problems communicating two ways

Part Number: SN65HVD230

Hi, 

I am trying to make a CAN isolator (from CAN to CAN), I am using the can transceiver SN65HVD230 to convert from CAN to TX, RX, and then an isolated CAN transceiver to convert it back to CAN. But when I try sending a CAN message I can only send it one way and need to short either of the two (TX, or RX) in the middle to allow the message to pass. When I have both lines connected, the message is not transferred for some reason. is there any chip that needs to be in the middle of the two CAN transceivers? or is there anything else that I am missing? Can someone please help me out?

Thank you

  • Hi Nakib, 

    Yes, you need to accommodation for the arbitration logic of the CAN signals without allowing the signal to feedback into itself causing the system to lock up. We have a reference design that does exactly this. You can use the arbitration logic from this design to ensure the signals are handled properly in the digital domain of your board. 

    Let me know if you have questions on this design. 

    Regards,
    Eric Schott

  • Hi Eric, 

    Thank you. I was wondering if there is any chip available with the arbitration logic or can we use the BJTs for the arbitration logic.

    Regards,

    Nakib 

  • Hi Nakib, 

    I don't know of any integrated solution for resolving this logic. The reference design uses a series of logic gates to resolve the logic. A BJT solution would be possible, but likely much more complex and larger than the one used in the example.

    Regards,
    Eric Schott