RSLogix 5000 PID code

[sa747sp 0]

Hi, can anyone help me to program a simple PID code for controling a valve. I just want to compare the set point with the process value and control the valve propoertioally Many thanks Frank

[Michael Lloyd 85]

I've used "stepper" logic before. Simply put it goes something like this. Start timer. Timer Done. Compare. If high increment output in the correct direction. Compare. If low increment in the correct direction. Start timer. Repeat. The Timer sets how often the state of the "loop" is tested. The Increment value sets the amount of output change. I usually put some dead band in there too.