I have a process temperature control unit that has 5 pid loops. The problem is when the setpoint is changed, all the pid settings need to be changed for it to work correctly. The setpoint range I have is drastic; -20 to 200 and is a very small unit. It's like controlling a shot glass of water with liquid nitrogen and a blow torch. Is there some add-on or device that will, I guess, auto tune the settings for when the setpoint is changed by the end user? We are using Micrologix 1200. Thanks!

Why not just change all of the variables when you change the set point?

I am not the end user, I am the manufacturer/programmer. All they can do is push buttons on the Panelview. When they change the setpoint, I need it to perform sufficiently.

In the program.

They push a button and the program enters all new variables.

Create a subroutine that is called whenever the setpoint is changed.:
If setpoint < 0 MOV N11:0, N11:1, N11:2 to the pid gains and return
If setopint < 20 mov N11:3, N11:4, N11:5 to the pid gains and return
If setopint < 40 mov N11:6, N11:7, N11:8 to the pid gains and return
If setopint < 60 mov N11:9, N11:10, N11:11to the pid gains and return
etc.


You haven't given much specific information on the process, but a better method might be to select the gains based on the actual PV, not the setpoint. Then as the actual PV changes through the range towards the setpoint, the gains change as needed.

I may try that idea. Thanks for the advice!

No Problem.