First question: How dangerous is this system you're working on? In other words, if things get out of hand, is someone likely to get hurt? Or are we just going to let off a little extra steam?
Second question: How familiar are you with the SLC-5/03 analog signals? For example: Is your input scaled from 3277 to 16384? Is the output signal scaled 6242 to 31208? If not, how are they scaled?
Third question: Is your system already far enough along so that:
1. you can monitor the input signal in your SLC? and
2. you can manually control the output by entering values into the output address?
Basically, you've got to have good inputs and outputs before you try for automatic control.
Fourth question: What is your deadline on this project? "As soon as possible" is NOT a valid answer.
Fifth question: Does your version of RSLogix500 have the Trends (graphing) feature available?