PID module has gone to control-point

Issue

PID module has gone to "control-point"

Product Line

TAC I/NET

Environment

  • I/NET DDC
  • PID

Cause

The PID may have gone to "Control Point" due to unforeseen circumstances and is causing a problem. "Control Point" can also be used intentionally as a control strategy.

Resolution

Four reasons:

  • If the Setpoint’s value crosses above or below the high or low input limits as populated in the PID editor, this will force the PID to go to control-point.
  • If the process variable should reach the low or input sense limits as entered in the Resident I/O editor, the PID will go to control-point.
  • If either the Setpoint or Process variable should go to "OLD" status, the PID will go to control-point until the "OLD" flag goes away.
  • If the user should change any variable within the PID, when exiting the PID editor, the PID will go to control-point until the next scan of the module. For more information on this subject refer to Tech Tip G062.