PID parameters settings

[nasir_ash 0]

Dear Mates, Happy New Year!!! i am new in plc programming, want to learn use of PID command i am using a 4-20mA input and scale it (#30---#7FF that converts to 0--100) make a small step for continous change of the input and getting a perfect output after scaling when i am using the scalled output in PID command, as Input word and setting the parameters as below, getting no output. the error flag is ON ( program is attached) For C #100 For P, C+1 &500 For I, C+2 turn if off &9999 For D, C+3 turn if off &0000 For t, C+4 say &50 which corresponds to a 0.5 sec sampling period Leave C5 &0001 C6 #0404 C7 to onwords not using please help me, whats going wrong here. regards NASIR PID TEST.cxp

[PMCR 66]

NASIR When I do PID in an Omron PLC, I use '9' for digit xxXx in C+6. Instead of 0404 in D00036, try 0494.

[nasir_ash 0]

Dear Mate after making settings dm36=9999, or dm36=0494 the P_CY flag turn ON and OFF, Try to reduce the Prop Gain to 50, and fixed the sampling time to 0.1s, b but the out put is still ZERO.

[nasir_ash 0]

Hi team i am still waiting for a reply regards Nasir

[Geir 4]

Hi, here is an example of PID control that is copied from a program for CJ2H, but I have tried to strip out the incompatible parts. Also, the parameters are supposed to be entered from a PC-HMI, but there should be no problem just entering them directly into the program.

PID example.cxp

[Michael Walsh 268]

It is a good idea to set the "Work Area" of the PID function to 0 on first scan. In the attached example above, you would do a BSET #0 D3109 D3138 to set the values of D3109 to D3138 to 0 on the first scan (P_First_Cycle). Adding this one step has fixed issues with the PID instruction in the past for me. It is recommended in the programming manual.

[chelton 66]

Also, The PID instruction does not operate in simulation mode , you need the physical hardware.

[Rabid 0]

Thank you for this great info!

[chou 0]

Dear guy,

how can i download the above example?

i cannot see any link or button to download it. Please guide. thanks.

[Michael Walsh 268]

Chou, there was issues with a recent site update.  I have added it back to the post for you.

[chou 0]

thanks Michael.

[crazy colosus 0]

Hi

I have a problem with PID function on a CP1-e plc.

I try to simulate the PID in the CX-Programmer with no success .

I try all the variant PID, PIDAT, but i do not obtain any value to the output word.

Any solution?

Is an limitation of the program ?

Thank you

[pfort 20]

It is normal, it don't work in simulator.