PLC PID loop tuning


Thread Starter


Please let me know, whether modern PLC like modicon quatum etc do have the PID tuning function block at PLC processor level or at SCADA level? In SCADA system, the PID auto tuning option is a soft option or hard option?

In case, the SCADA system fails, then how the PID loops behave, does the system run independently like any other DCS?

David Ferguson

The autotune feature is built into the Controllogix processor at the
controller level.

Dave Ferguson
Control Systems Engineer
There is no single answer to your question. Some PLC's have auto tuning features, some don't. Some work well, most don't unless you understand how and when to use them and apply the results properly. Please do not believe the sales hype that implies auto-tuning will magically and perfectly tune every loop in your process. It will require your expert input as well.

PID control and Auto Tuning are two separate functions. If you loose the SCADA then the PID controls - and everything else in the PLC - *should* continue to function normally. Whether it actually does or not is a different issue.