structured txt pid formula

[professor_jonny]

im looking for a structured txt formula for pid that i can modify. yes i know i can use a pid function block ut the pid equasion i have has had an process enginer tweak it slightly over the generic one with feed forward modeling and i dont know how to preform the intergral part of the calculation as i dont know how to enter the anti derivitive part of the equasion in the plc. would someone be able to help me? im working on the nj plc but i asked here as more may have this platform

[Sleepy Wombat]

If you dont know how to use the inbuilt PID function, then even if you have a process engineer tweak it, i dont understand how you would understand an ST PID. BTW how can you tweak something that is not running, if you mean modify a PID equation then thats different. If you have the process guys pid you could write a ST your self using the standard math functions in the PLC. there is a lot of work involved in writing one from scratch, and you need to understand the engineering behind it. To be honest, I would suggest you get a dedicated standalone process controller (omron temperature) and use that for your pid.