In my oven, when it is too hot I turn the output to the heaters off, and
also set the I term to zero.  The controller can't GO any lower than off, so
I term doesn't accomplish anything, and I don't want positive values of I
stacking up and canceling the negative values of I which will be seen after
the oven cools below the setpoint.  I think you need to dump the I term
every once in a while.  When P=0 would work great if you have proportional
control of your output.



-----Original Message-----
From: Tjaart van der Walt <tjaart@WASP.CO.ZA>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Monday, May 17, 1999 11:54 PM
Subject: Re: PID algorithms in PIC C

Good advice. I have noticed another thing that can make your
system much more immune to the low-frequency I-oscillations :
Reset the I-value to zero whenever P=0.

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