Bit of a puzzle, this one. 19200bps is correct, and the circuit I have wired up for it works perfectly fine with the AUX bus scanner project elsewhere on CN.
But CPWI has yet to behave.
On the trace, I can see it sending GET VERSION commands to the AZM_MC, and I can see the AZM_MC replying correctly to those commands. Yet.. CPWI behaves as if it never sees the response, and retries after around 200msecs, over and over until it gives up (and locks up too, have to kill it from the Task Manager).
It probably has something to do with the RTS/CTS lines from the virtual serial port. The Arduino's USB-Serial doesn't appear to implement them, though the code inside the Arduino does do proper handshaking on the AUX bus side.
I think I'll try an FTDI serial adapter between the Arduino and CPWI instead of the built-in USB on the Arduino. With the FTDI I can tie RTS and CTS together to keep CPWI happy. Maybe that'll work..
Edited by mlord, 23 February 2021 - 12:10 AM.