PID Control

junkerjorg · Sep 17, 2008

I have been given the task of programming a PID loop to control a product pump off of a pressure transmitter. This will be my first PID loop and I'm not really sure how to do this.

Would someone be willing to help me through? I would greatly appreciate it.

PLC is a PLC 5/80 - I/O is already all mapped out
4-20mA and right now I am assuming 0-4095 on the scale
Inverter is AB Powerflex 40, Speed controlled at O:037.3
Pressure xmitter I:035.5

Thanks!!

aiki202 · Sep 18, 2008

There was a recent thread on this subject that was excellent. It may/should help you.

http://www.plctalk.net/qanda/showthread.php?t=41688

boardmaker · Sep 18, 2008

There are a lot of PID threads. If you look up at the top, use the search function. I however, am not a pid guru. Look for posts from guys like Peter N. or Ron B. They are very very informative. Unfortunately for me, alot is over my head. Good Luck.

junkerjorg · Sep 18, 2008

Thanks, I'll take a look!

junkerjorg · Sep 18, 2008

Well that gave me a little insight but it wasn't quite what I needed. I did manage to sort it out though. Thanks for the input!!

Paullys50 · Sep 18, 2008

Check out controlguru.com, I've linked you to his table of contents, start reading at section I.2 "Heat Exchanger Study" continue into the other sections and read everything that relates to the Heat Exchanger, once you've understood that, start reading each sub-section. He does a great job of teaching the fundamentals of the PID and how to go about tuning, it isn't specific to certain PLC's but a good overview of the PID concept. Once you understand the concepts turn to the PLC 5 instruction set manual for specifics on setting up the PID in the logic.

Ron Beaufort · Sep 18, 2008

Greetings junkerjorg ...

sorry that I don't have much spare time right now - but if you'll post your existing .RSP file, the other forum members and I will be glad to take a look at it ... for one thing, I'm not sure what addresses you had in mind, but the ones that you listed in your first post don't seem quite right for analog signals in a PLC-5 system ...

I recommend that you let us help you nail down the addressing and the scaling before you try tuning, etc. ...

junkerjorg · Sep 19, 2008

Ron,

I appreciate the response, I know you are a very busy man! As I stated I did manage to sort things out but here is a screen shot for you to review. I apologize for the addresses, they were the physical addresses where the components are to be wired.

Regards,
Steve

junkerjorg · Sep 19, 2008

Paully's5.0 said:
Check out controlguru.com

Thanks Paully!

PID Control

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