Hi, I am new to the forum, so I hope I am in the rigth spot.

I am working on a thermostat for a calorifaire heater, the fan speed needs to be higher when the difference between the desired temperature and actual temperature is high and slower as the two temperatures approches each other.

I am using a LOGO 7 0BA7 with AM 2 and AM2 AQ.

I would like to make the setting of temperature using the up/down keys on the LOGO and compare the set temperature with the input from my PT100.

I have come as far as setting up the PT100 input and making a UP/DOWN counter for the keys, but how can I compare the values between the two signals and have a higher speed of the fan if there is a big distande between the valus and a lower speed as the number come closer to each other.

I have thought about using the PI for the output, but I can not figure out how to create the block between them.

Hope someone can help.

This was just perfect, function is excactly what I needed, I just changed the direction of the PI, then it works as it should.

I will spend some time going through it, to fully understand how it actually works, but that is good learning.

Thank you very much for the support