Sounds Fun
I agree with Tom on the non-linear(ness) of pH control.....In my past life I was "the pH guy" and spent countless hours trying to nail down pH control at the sugar plant I worked at. I have some great whitepapers somewhere written by "Dr. pH", a gentleman who works for ABB and dedicated his life to pH control. If anyone's interested you can PM me and I'll try to dig them out.
At any rate, I actually have a pH control application coming up at our plant. We will be controlling our sewer discharge pH with CO2. Looks like it will be pretty basic single loop control, one control valve and a sensor.....the control band is relatively wide 4.5-9.5, we'll see how it goes. I actually planned to use a Compact Logix PLC, I will give the PIDE block a shot. Briana, let me know how your installation goes. What are you trying to control the pH of?
Greg
***Quick Edit: Scratch the whitepaper offer, I just dug and realized I tossed the floppy they were on about a year ago.....I vouched I'd never do pH control again. However if you do a google search for "Don Spriggs" and pH, you will find several good articles.