Hello Pranam;

There are particularities for the functionning of FB 41 that you should be aware of, to make your PID control easier to manage. For example, on startup, the PID loop is in manual, you must place it in Auto mode yourself. And the COM_RST signal must show a rising edge for it to activate FB 41, so we would set it in OB 100, and reset it right after the FB 41 call, in OB 35 (see these links for more information):

https://support.industry.siemens.com/cs/ww/en/view/18459342

https://support.industry.siemens.com/tf//ww/en/posts/pid-fb41-block/234826/?page=0&pageSize=10

Hope this helps,

Daniel Chartier