AB PLC5 PID questions

[Ken Moore]

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.

[NetNathan]

Originally Posted by drbitboy

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...

[NetNathan]

Originally Posted by Ken Moore

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...