PID Loops

Hi everyone,

I am trying to figure out a total understanding of the PID closed loop system. I have read over and over all the info I can find on this a few times in the past, and would really like to set up a closed loop system. I have asked in my instructors in the advanced plc classes if we were learning PID's and to my surprise we were not. (only reading about them). I come across these systems all the time but do not fully understand all of it enough to set a system up. Does anyone have any suggestions to research more into this. I also over the weekend had to change target values for a batch mixer and would like to understand 100% the program for it is a very large program.

Try the ISA website or google PID there's lots of info out there as well a few good post here. I recomend understanding the theroy of PID first then how YOUR plc handles the instruction.
good luck, Steve

The wikipedia article isn't bad:

http://en.wikipedia.org/wiki/PID_controller

Fundamentally proportional control says that if a measured parameter, say the temperature of your shower water, isn't right then you have to adjust an output, the faucet position. The farther off the temp is the more you crank the faucet. You keep tweaking until the temp is just right - that's integral. And from experience you know that the water will keep warming up after you stop cranking the faucet so you stop short if it is getting warmer quick enough - that's derivative.

closed loops

Try PAControl.com.loads of information for closed loops as well as training exercises.

Some more good reading material.

http://www.ronbeaufort.com/sample_lessons.htm

http://www.google.com/url?sa=t&sour...9uWzAg&usg=AFQjCNEdUM11a3L5YhBfZOTvRTw9KIfSSw