Posted 14 Jun 2016 I have a PID loop controlling a flow control valve based on desired fluid flow. In the idle state, I set the flow control valves to be 100% open. Occasionally, the PD25:0.CVP drops very briefly to zero and recovers back to 100% within 10 seconds. Nothing else around the PID controller changes that I can see. The output 4-20mA signal to the flow control valve does not move. This happens when the PID loop is running as well. For instance, the FCV will be open 20-22% controlling the flow as required when it will drop the CVP % to zero causing the PID loop to snap into action to recover back to 20%. Anyone ever seen this phenomenon? Share this post Link to post Share on other sites
Posted 14 Jun 2016 (edited) Is there something in the program writing to the output other then the PID instruction? (PD25:0.CV) Also check for something controlling the auto/manual bit( PD25:0.AM) Post your program, its .RSS file and someone can help you look. Edited 14 Jun 2016 by Mickey Share this post Link to post Share on other sites