Not USB. I had flaky Modbus on a Pi 3 once and part of the fix was taking console=serial0,115200 out of cmdline.txt, the login console was sharing the port. Not sure that’s your whole problem though.
QoS 1 and a lot of patience.
Not USB. I had flaky Modbus on a Pi 3 once and part of the fix was taking console=serial0,115200 out of cmdline.txt, the login console was sharing the port. Not sure that’s your whole problem though.