One PID for two systems

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Hogarth
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One PID for two systems

Post by Hogarth » Tue Aug 15, 2017 1:54 pm

I'm using the same PID/SSR set-up for both my five-gallon HERMS and my one-gallon recirculating system. Obviously each system will need a different set of parameters. I know I can autotune the PID, but I don't want to do this each time. Can I autotune it once for each system, and then manually input the parameters when I switch from one to the other? And is it just the P,I & D parameters that would need changing? I don't quite understand PIDs, TBH -- bit above my head. :? Thanks!

AnthonyUK

Re: One PID for two systems

Post by AnthonyUK » Tue Aug 15, 2017 4:53 pm

You can do that with the Sestos ones.

How different are your systems. I use the same PID on my Buffalo which is 2600w and a DIY boiler using a Tesco element 2400W without changing any settings.

aamcle
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Re: One PID for two systems

Post by aamcle » Tue Aug 15, 2017 9:30 pm

you can get PIDs that store more than one profile but they cost more, what about getting a second cheap PID on evil bay?

I wouldn't have thought that running an autotune would be an issue, on my PID I can limit any overshoot so I can auto tune as I brew although I prefer not to.


aamcle

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Hogarth
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Re: One PID for two systems

Post by Hogarth » Thu Aug 17, 2017 11:14 am

Thanks. In terms of mashing the systems are quite similar, so perhaps I can get away with using same parameters. Another possibility is using two pids and one ssr though I suppose you'd have to put a switch in.

Fil
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Re: One PID for two systems

Post by Fil » Thu Aug 17, 2017 10:19 pm

I suspect at our volumes that the parameters for one task will be close to if not the same as for another, these are industrial control instruments.
It might be worth an afternoons testing to find out. since tuningg my pids ive read that to save time with the autotune you can start the process with warm/hot water from the hot tap ;)

if using 2 x pids to control a single ssr simply ensure one is turned off all the time by using a double throw switch to supply the power to the pids, or if using pid #2 for temperature reading use a 2 pole double throw switch on the dc ssr control + feeds to ensure only one pid is controlling the ssr at any one time.
ist update for months n months..
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