SLC 500 PID Setup

justin lutz

Member
Join Date
Aug 2008
Location
Columbus, Ohio
Posts
93
Good morning, All.

Equipment:
SLC 5/03
1746-NI8 Analog Input Module
1746-NO4I Analog Output Module
Flowmeter, transmits a 4-20mA signal

I have a sludge pump whose speed will be dependent upon the flow rate transmitted by the flowmeter (Increase speed to increase flow rate, decrease speed to decrease flow rate). The client wants to operate between 300-600GPM. Thus, I am looking to set up a PID for this application, however I do not have any experience in doing so. If I have it right, my PV is the flow rate, while my CV is the pump speed.

Question #1: The analog input module will scale the transducer input (4-20mA) from 0 - 16,383. Do I want to set things up such that 0 = 300GPM and 16,383 = 600GPM, or do I want 0 - 16,383 to represent the full scale of the transducer, say 0-1000GPM?

Question #2: I have attached a zip file with 3 rungs of logic in an attempt to set up a PID. The only things I have entered in the PID setup so far are SP, Smax, and Smin. According to the info. that I've provided, does this seem correct?

Any comments/advice would be greatly appreciated!


Thank you,
Justin


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Greetings Justin ...

you've got more "issues" than I have time to type right now ... but if you want to give me a call within the next hour, I'll try to talk you through this on the phone ...

let's assume for a minute that I do that ... what you should be willing to do in return for this free advice is to fully document the setup that results and post it on the forum so that it will be helpful to others in the future ...

disclaimer: since you don't have the machinery (or even a processor) to try all of this out on, anything that you and I can come up with is going to be "sketchy" at best ... but if you want to give a shot - just give me a call ...

here's a reference if you're afraid to call up some potential "nut case" from the forum ...

http://www.plctalk.net/qanda/showthread.php?postid=55447#post55447

sorry I don't have much spare time these days ... but talking is quicker than typing ...
 

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