Important things to know about a Studio 5000 PIDE instruction for AutoTune

Some of the problems I see people run into which can save you a lot of time dealing with the PIDE instruction in Studio 5000 or RSLogix 5000.
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[@seeigecannon]

Thanks for this. Can you give us a range of PID values that you would expect to see in the field? As in if you were to see those numbers they wouldn't immediately jump out as being wrong?
I have been working on a Budzar chiller, and the PLC programming leaves much to be desired. All of the PID gains from the factory were set to 5, 20, and 0 respectively. The system was horrendously unstable, and I went a long way to fixing it just by setting the MaxROC value to 0.1, but I am currently nowhere near groking the AB PIDE instruction. I do have the main refrigerant expansion valve working much better now though using a PID of 3, 0.25, and 0.
Keep up the good work.

[@ShaneWelcher]

Every PID is different and depends on device reaction timing

[@seeigecannon]

@@ShaneWelcher I do understand that, but lets say someone set the PID of a heater (lets say for a bedroom) to 50,50,50; would that immediately jump out to you saying there is no way that is correct? What range would you expect (order of magnitude)?

[@ShaneWelcher]

@@seeigecannon
Are you saying
P 50
I 50
D 50
?
If so, that wouldn't work properly.
Low P, higher I, limited D
Based on the task rate of the scan

[@seeigecannon]

@@ShaneWelcher Thanks. Do you have any rules of thumb, like for a fast process P = high, I = low, d=high or something?
Sorry for the bunch of questions, I have just never seen the values of a PID loop in the real world before where I am confident it has been tuned correctly, and on top of that, AB uses a velocity equation instead of a positional equation, so what limited experience I have with positional PID doesn't seen to translate properly.

[@ShaneWelcher]

@@seeigecannon
Depends on the task rate for scanning the PID along with if you care if it over shoots and settles or if it needs to not over shoot by being slightly slower