Many - many years later, I can confirm that fslurp works excellent in combination with the Fronius IG TL over RS422 in full-dublex mode. - I used a RS422 HAT (Shield) for my Pi 3B from HWHARDSOFT in Germany (https://www.hwhardsoft.de/2017/10/07/rs422-rs485-raspberry-pi-hat/) - The DATCOM setting on the Fronius inverter has been set to INTERFACE. - For some unknown reason, I had to reverse the A and B line. Kudo's for David, fslurp still works excellent after so many years after it's conception!