I looked through the modbus registers but do not see the PID Prop value specified. Is there a way to alter it through modbus or through code? Since it determines the deadband width, it would make sense that this can be changed remotely and not require the T3000 software to do so.
As well, can this value be a floating point number or is it only integer?
I’m not sure that the PID terms are exposed as registers, you could have a look through the register viewer tool. If they are not there we could consider adding it to the todo list.
update: I see that you already checked through the register list. Apologies that the PID terms are not exposed over Modbus. In my experience they are pretty much set and forget, these PID terms. If you are dealing with I term windup when the system is down there is a workaround, simply temporarily set the setpoint equal to the measured temperature.
10 IF FAN101 THEN SETP101 = DAYSETP
20 IF NOT FAN101 THEN SETP101 = ROOMTEMP