Dragance86

Hello,

I need your help with pid function block fb59, it's parameters QLMNUP and QLMNDN actually. My application is to control the temperature in the tank. A temperature is measured by Pt100 and I have digital output for heater. I tried with fb59 but my outputs QLMNUP and QLMNDN are always zero. See the attachment:

Dragance86

Not suitable or not impossible? I've read about FB58 and maybe not well understood, can FB58 be used If the input analog and digital output? Because it is student project and the only way to connect the inputs and outputs.

Thanks for your reply

• It is not possible to regulate a process via a heater with FB59.This is a limit forced by type of actuator and an adaptive PI algorithm.
  
  
• FB58 is what you need despite the complexity of the algorithm.Check the mentioned sample in STEP 7 plus THESE clustered threads for more information.
  
  
• Upload your project here for more hints.