In my team we are performing some CAN tests using PCAN-USB and PCAN-USB FD. We have faced some differences in handling no connection to any other node. Attempting to send frame via PCAN-USB (white one) makes it become Bus Passive State While PCAN-USB FD (black one) remains active: We are wondering what is the reason of such difference and which approach of handling this scenario is the most common?
Best regards, Paweł Gmurczyk
On a CAN-Bus there always need to be at least 2 nodes present, otherwise the messages sent cannot be acknowledged and will lead to error states.
The PCAN-USB FD does need a termination to operate correctly, most likely you have also removed the termination hence why the node stays active.
The hardware on PCAN-USB and PCAN-USB FD is different, where the PCAN-USB is a SJA-1000 hardware, the PCAN-USB FD used an FPGA. Furthermore do both devices use different Transceivers.
And what do you mean by "handling such a scenario"? Ideally, at least 2 nodes are on the bus, the error will always show up
if no other nodes are present when sending CAN-Frames.
If it is present on a bus with other nodes active it most likely is a physical issue:
-> Other nodes are in listenonly-mode (Do not acknoweldge frames, transmitting noce gets no acknowledgment)
-> Missing termination
-> Wrong bitrate
-> broken cables, etc.
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