Temperature Control 2-PID control FB - problem

3 posts in this topic


In document  2-PID FB   I found FB for 2-PID control

I downloaded this FB  - attached 2-PID Function  and I set the same values what are in example and still I have error:


Can I get any clue where is the mistake. Parameters looks correct


Thanks Pawel





Edited by pszczepan

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From the help file (example) that you attached:


  • If no PID parameters are stored, the function block shall generate a #0601 error when attempting to enable the 2-PID function. The user can manually start the Auto-Tuning Process causing the status code #0002 to occur. While the Auto-Tuning process in ongoing, the AT_Status bit is turned on and will turn off when the Auto-Tuning process has been completed.

You need to put values in for P, I and D. 


You can see the acceptable ranges below (also from the file in the .zip file):



If you do not know what to put in for P, I and D, turn on the Autotune (Start_AT) bit and see what OUT_P, OUT_I and OUT_D results you get.  You can then enter them for the P, I and D inputs.


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Now it works. So finally procedure looks like:

first start - write 1,1,1 to P_Input, I_Input, D_Input and set Write_PID_Input

after that,  set ENABLE=1  set also START_AT=1.

After some time OUT_P, OUT_I, OUT_D will get new values.

Now I have question:

 START_AT should be all the time =1 and values  OUT_P, OUT_I, OUT_D will be optimized or just once to get new   OUT_P, OUT_I, OUT_D.

After I receive new  values OUT_P, OUT_I, OUT_D should I write this values to P_Input, I_Input, D_Input for future needs. When I will need it - when PLC battery will be low? 


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