PID Output not consistent

Hi, I have a problem where I am noticing the output of the PID is “flashing”. This is part of a cascaded controller but can be broken if needed. It seems that when it calculates the output it is not taking the value from the previous calc but just starts over. Anyone explain this?

Hi Brett, welcome to the forums!

Off the top of my head, sounds like there is another PID or more likely a bit of code that is writing to the same output (or something else linked to that PID loop) causing it to ‘flash’.

Are you using PAC Control or Codesys or something else?
Do a ‘find’ and look for that loop and its parameters, make sure its only being referenced as and when you expect it to be.

2 Likes