I have a a device(s) in which a serial port data is transmitted via CAN transceivers (not my design) to another device with same arrangement. Only these two devices are ever connected to this communication line.
The transceiver functions oddly. The AB pin is tied to ground by hardware. I have verified it multiple times with different meters. So autobaud loopback mode is not in use. Still somehow exactly the same data my MCU sends to D pin is reflected back from R pin. I have verified this with an oscilloscope. There is no short-circuit between D and R pins. This happens even when the CANH and CANL are not connected to anything.
I have noticed this behavior on different boards.
Does this happen because the transceiver is not being driven by a CAN controller but a serial port peripheral?
