pump control

Anyone know how I can use a PID2 loop (modicon) to pace 3 pumps from a flowmeter? Pump should start in a certain sequence and they should be all at the same speed if they all run at the same time.

Since the output is 0-4095 from the loop, i was thinking to use that. If 2 pumps run, then start using the RAMP (PCFL) function to start 2nd pump until they match. Too bad I don't have a simulator so I don't know if my logic will work

Anyone can help with this? Detail modicon ladder logic will be appreciated.

Simulator Alternative

I'll tell ya what....Instead of using a simulator to test your logic, if you post your ladder here I'd be willing to bet you will get several excellent opinions on your code. If you don't have much started on your code yet, post what you have completed and I'm sure one of us will kick you in the right direction. Do you know why you're running them in lead/lag vs sequential control? There's been many posts on here regarding the theory of why people run pumps lead/lag on VFD's and it's not always justified.

Greg

I second Greg. Modicon is my least favorite PLC, (or more exactly, most disliked PLC), but I do have a lot of experience with them nevertheless.

Post your code, we'll take a look at it.

I am still working on/thinking about it. If someone can start me off with the right direction, that will be nice. The reason why I need it to do it that way just because the control/process person want it that way. What can I say?

OK, it seems that you don't know where to get started.

This is where "top down" software design comes into play. Start with a complete description of the process in plain language. Then break it down into smaller plain language statements until you get to the level of statements that you think can be represented in ladder on a single network. If you can't represent this on a single network of Modicon logic, then you need to break the statement down more. While I have my gripes about Modicons, and they are many, the network topology of Modicon PLCs does lend itself to top down design techniques - so take advantage of it.

You will find lots of help here, but you won't find someone who will do it for you. So lets say we get started with a detailed description of what you need.