Changing an Analog value via HMI

There is an thermal system with three analog values:
X:room temp.
Y:set point
A:control signal
I'd like to change the setpoint with my TP170A. When I try to change it,(that is in MW2) nothing happens I've used IO field and also a button's SetValue function.
Thanks.

If you used a IOField directly linked to MW2, it should work unless MW2 is being overwritten in your PLC.
When you change it on the TP170A, does it revert back to the previous value? If yes, then it's most likely it's getting overwritten in your PLC.

In my PLC program , nothing changes MW2. I just set an initial value in OB100. It's value doesn't change.