I have been fighting with the tuning of this PID loop for a week. Any suggestions will be appreciated. PLC is a GE Fanuc Versamax Micro, programmed with Versapro. Application is control of system pressure via a pump and a vfd controlled by the analog output of the plc. I am faulting on low pressure (drive not ramping up to meet demand). Tuning Parameters block set up as follows: P-3.50 D-0 I-0 sample period-0 bias-0 Db upper and lower-0 Up clamp-32000 Low Clamp-16000 Error term-SP-PV Min slew-0 Deriv. action-Error Output action-Positive
I do not think you can have the sample period set to 0. Try modifying this parameter.
If you are commanding speed reference on a VFD with a 0-10 analog make sure you have the accel/decel high enough to handle the ramp speed of your PID.
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