Moonlight, at it's simplest, PID control works by operating on an error signal,or the difference between the desired output and the current output.
So, in order to implement PID control, the first step is to calculate that process error.
Second, you now need to multiply that process error by a proportional (P) constant, an integration term (I), and a differential term (D). Then add up those products.
There are MANY ways to do the integral and derivative terms, so I will leave that to you. Search for PID on the NI website, and you will find at least one example of how to do it.
Good luck,a nd I will repost later with some examples.
Wes
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Wes Ramm, Cyth UK
CLD, CPLI
