Hello Friends,

First off all, good days.

Best Regards

Hello 3dautomation;

I can suggest a collection of descriptive articles on closed-loop control:

Ron Beaufort's What is P in PID?

Ron Beaufort is an American programmer and PLC trainer with a great reputation. He mostly works with Allen-Bradley PLCs,  but these articles discuss PID with a minimum of math and are mostly independant of the controller you want to use.

Once you have a grasp of the notions of P,  I, and D in closed-loop control then it will be easier to apply them on the type of PID controller you want to use: FB41 for S7-300, PID Compact for S7-1200...

Hope this helps.

Daniel Chartier