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SN65HVD251: about building network for SN65HVD251

Vera Mao
Expert 5065 points
Part Number: SN65HVD251

hi dear supporting team,

for SN65HVD251, each one of it could support 110 nodes, now customer need support 250 CAN nodes, could they use below way to build the network? 

the yellow portion is  CAN repeater brd, there are two CAN circuits inside.  using one MCU to do CAN communication internally and the CAN repeater with external, CAN transceiver are all SN65HVD251.  there are 50 nodes in each repeater.  totally 250 nodes. is it ok to do this way to  enhance the CAN signal? tks a lot!

  • 0
    TI__Guru 74252 points

    Vera,

    Theoretically this should work, but I want to make sure I understand how this works. Each node has an SN65HVD251 + a CAN controller, then each of these nodes is talking to one MCU which then delivers that to the CAN repeater, and that goes to the external CAN bus. Is that correct?

    One thing to keep in mind is the added propagation delay due to CAN repeaters. The CAN bus sees the CAN repeater essentially as more cable, and to calculate the propagation delay, in general CAN repeaters are the equivalent of 40m of cable. Adding these will limit your data rate, since the propagation delay will be increased, but if you're communicating at a low speed, this won't be a problem. 

    What data rate is the customer working at?

    Just for clarification, is one MCU handling the communication for all 50 transceivers at each repeater circuit?

    Regards,

  • 0 in reply to Eric Hackett
    TI__Expert 5065 points

    Hi Eric,

    thank you for your answer!

    yes, your understanding is right, but the CAN repeater are also MCU.  and the data rate is 500kbps.  the distance btw each CAN repeater is no longer than 2m.