Joa Posted April 2 Report Share Posted April 2 Hi all, I want to control a flow control valve using the PID function. After the autotune run is completed and the Status is 4, the CV control value goes to 0 instead of dynamically adjusting the value. May someone had the same problem when using an analog output? I would be very grateful for tips and advice.. BR, Joachim Link to comment Share on other sites More sharing options...
Dave Posted April 2 Report Share Posted April 2 It looks like your PV max is set to only 30, but your actual PV is at 741. I would have expected to see a status of -6, not sure why its not Link to comment Share on other sites More sharing options...
Joa Posted April 2 Author Report Share Posted April 2 Hi Dave, thank's a lot for your response. sorry the screenshot confuses a little bit. The PV max value is multiplied by factor 100 in the ladder later...so it's actually 3000. In attached another screenshot with all values used by PID Config when Status is 4. (PID RUN) I'm not sure if all values are plausible because I don't have much experience with it.. Would be great to here from you again.. Link to comment Share on other sites More sharing options...
Saragani Posted April 2 Report Share Posted April 2 Btw, Status 4 means running. I think it should return to 0 when completed. Link to comment Share on other sites More sharing options...
Joa Posted April 2 Author Report Share Posted April 2 Thank's for the commend... I understand Status 4 means PID is running. ....but I don't understand why CV is 0 when PV differs to SetPoint Link to comment Share on other sites More sharing options...
ORSO2001 Posted April 2 Report Share Posted April 2 Hi @Joa attached a short video about the PID that I am using in the project that I am doing...the CV is used to manage a timer to ON/OFF a digital output...the PV is emulated increasing/decreasing a variable referred at the status of this DO. The autotune BIT is "0" because I did it before...stored that vale in a DTI...save to a file..so every time that i energize the PLC it is uploaded and th ePID can run ok without a new autotune. howevere I tried to immediately run the PID after the autotune and it works in the same ways as in the video. also I tried to replicate what you show...I think...and it works... so...one question is...how are the "control value derivative" and the "integral error" at the bottom of PID Config struct (missing in your picture)? PID.mp4 Link to comment Share on other sites More sharing options...
Joa Posted April 3 Author Report Share Posted April 3 Hi, I checked the ladder again and found a little mistake in the logic. ....now it works Thank's a lot for your help & comments Link to comment Share on other sites More sharing options...
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