How do I tune the PID?

Describe your system and processes, and post your config file.
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BrunDog
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How do I tune the PID?

Post by BrunDog »

OK, I searched through the forum and the Wiki using both the search tool and Google... and was surprised to find no direction on how to tune the PID. Is everyone using the default settings? Does the PID tuner in the utility work in any capacity yet? Does anyone have any straightforward guides on how to tune the PID manually? I have a very dynamic control loop trying to rapidly heat room temp water in the RIMS tube, and while I am able to minimize the swings with manual adjustments, I would like to tune better than "change and see".

Thanks in advance!

-BD
BrunDog
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Re: How do I tune the PID?

Post by BrunDog »

OK, I guess nobody is quite sure.

How about this: when will the PID auto-tune utility be working?

-BD
RDH_Texas
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Re: How do I tune the PID?

Post by RDH_Texas »

I've had the same problem, and was looking around.
I found this. I have not tried it yet, but it may work.
http://byo.com/issues/item/299-brewing- ... ontrollers

Next time I have a few moments I plan to try a water run and see if I can get my RIMS system to control. Had no luck so far.
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oakbarn
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Re: How do I tune the PID?

Post by oakbarn »

Unfortunately there is never a good answer for this becuase of all the variables. If you got a PID perfectly tuned and then changed the Element from 1500w to 1800w, you would need to retune. There are people who will sell you PID tuning programs and spreadsheets. There are lots of You Tube Videos on it. BUt it is generally Trial and Error. There are people that have a whole job of doing nothing but tuning PIDs. It would be almost imposible to give any really good answer because of the complexity. I find it very confusing myself. I have found that the defaults eventually seem to work, although sometimes I am a degree low after some time so I just bump it up a degree,

I know there is a PID tuning Utility that is available for ver 4.o, but I have not used it yet. Maybe there is an engineer that can tell you where to start, but I have not seen any answers yet to this type of question that you can take to the bank.
clearwaterbrewer
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Re: How do I tune the PID?

Post by clearwaterbrewer »

BrunDog wrote:OK, I searched through the forum and the Wiki using both the search tool and Google... and was surprised to find no direction on how to tune the PID. Is everyone using the default settings? Does the PID tuner in the utility work in any capacity yet? Does anyone have any straightforward guides on how to tune the PID manually? I have a very dynamic control loop trying to rapidly heat room temp water in the RIMS tube, and while I am able to minimize the swings with manual adjustments, I would like to tune better than "change and see".

Thanks in advance!

-BD
did you look at wikipedia.org? It is referenced in the ECC Wiki... Great reference with pictures of what the values of P,I, and D each do when the other two are held constant.

tell us about what you are using the PID for, what your current settings are, and what is happening that you do not like...


General PID information:
remember, for some controllers( it does not appear that this is the case with the BCS) 'I' value 'Ti' is inverse...

change one thing at a time, and when changing, add or subtract 25-50% of the current value and watch what happens.... you will know pretty quick if you went the wrong way.

is it slow to respond, but reaches the setpoint and possibly overshoots just a bit? (increase P)
is it approaching at the right speed, but never, or waaay too slowly coming to the right temp? (increase I value)
is is overshooting, then undershooting? (decrease P and/or I)
BrunDog
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Re: How do I tune the PID?

Post by BrunDog »

What is the status of the PID tuner? When I try to use it, I only get a 405 - Not Allowed error...

-BD
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