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Old April 8th, 2021, 02:13 PM   #31
Ken Moore
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The setpoint should be compared to the EU range, which in this case is incorrectly configured. The PID block scales the input PV (0-4095) to Engineering Units, and then calculates the error from Set Point. (Also in EU). The print outs show EU of 0-4095, it should be what ever the input scaling is (assume Type J) then 32-1400F.
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Old April 8th, 2021, 02:33 PM   #32
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Quote:
Originally Posted by drbitboy View Post
The bang-bang behavior suggests otherwise, and it depends on how the output is scaled, but with the PV range set to [0-4095] and the temperature in degrees, a 1 degree change is 0.025% of full scale, so 50 is not the most outrageous proportional gain.


Or am I still not grokking the scaling of the PD-based PID?
Going to have to wait till I get there to find out what is true settings.
The screen shots I sent of the PID were from 2011... I ASSUME no one else has been in the logic...
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Old April 8th, 2021, 02:34 PM   #33
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Originally Posted by Ken Moore View Post
The setpoint should be compared to the EU range, which in this case is incorrectly configured. The PID block scales the input PV (0-4095) to Engineering Units, and then calculates the error from Set Point. (Also in EU). The print outs show EU of 0-4095, it should be what ever the input scaling is (assume Type J) then 32-1400F.
Type K is control...
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