Dear user,

Tell me what parameters affect the peaks and their frequency (highlighted in white). (FB41//CONT_C)

Thank you.

 Oscillation in control valve (LMN) would be due to wrong PID parameters like very small Ti compare to cycle of FB41.

The peaks would be due to improper P_SEL,I_SEL and D_SEL manipulation that is possibly caused by programming error (overlapping memories).

I hope it helps,

hdhosseini

Just to add extra points:

1- About the period , you need to be sure what is the source of oscillatory response on LMN . There are 2 options , cyclic input change  or integration time. I don't have access to your parameters and nor more accurate  comments could not be provided.

2- About the peak , check the source of peak in process value or error. If the sampling time of the tag logging software is not at the CPU cycle precise , you need a professional cycle precise logging package.