Weirdly after that update/upgrade (which was the first thing I did when I turned it on) MODBUS seems to be working now. Have been able to read/write to the registers.

it just constantly prints the following:

Jul 22 15:21:53 RevPi38654 piModbusSlave[2860]: read access to process image failed: -14

Can you check the piModbusSlave log with command:
tail -f /var/log/daemon.log

I have a RevPi Connect + set up as a Modbus slave in PiCtory. I have a UR3e robot arm set up as the client polling the RevPi every second or so on port 502. The IP address is correct and the slave id is set to 1. But whenever I request data from the registers it always comes back as 0. Even if I set...