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BobLfoot

PID Loop Implementation

56 posts in this topic

Bob, what are we supposed to see? It looks like you have it tuned. BTW, you should start the data at a steady state condition and get at least 10% of the data in a steady state condition. You started the data with 100% output. That can't be steady state. The data is unusable from an autotuning point of view.

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BobL For those of use with RSTune can you post the sugar.tun file ? thanks

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You say it looks like I have it tuned. I am thinking that I need to examine the location of my room temp sensor. The loop for the gylcol valve seems to regulate well and control air temp good. The loop for the room temp which adjsuts setpoint fo the glycol loop seenms to drop them temp sharp at first and then be long in getting to final temp. Can't explain the why of that. Also curious about the term "steady state". What am I looking for to define "steady state"?

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Thanks Peter for the good feedback. Process is running for the week and "playing" with tuning will ahve to wait for Friday Night. I'll try the manual fixed output setting and record response for 5 mintues approach and let you now what I get.

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Using RSTune via right click from RSlogix 5 it did not create *.tun files, but with opening it stand alone here they are. sugartun.zip Sugar001 is the room temp as process variable and a fixed setpoint to create a setpoint for Sugar002. Sugar002 is the floating setpoint and the return air temp process vaiable to cotnrol the glycol cooling valve position. So far we have maintianed temp within limits for 24 production hours and 48 idle hours before that without icing the coils. Something not previously achieveable.

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