I am working on a heat recovey system and need to regulate a modulating valve in order to maintain a temperature set-point.
I have never used S7-300 PID control and reading articles on the forum, the standard FC does not get good reviews.
The problem is my valve output is not behaving as expected and thus bounces around, resembling on / off control rathar than an nice smooth PID action. The temperature value (PV) is read over Modbus and only updates every 5 seconds. I can have this wired in as a 4-20mA signal if need be, but the temp change is relativly slow, so I doubt it's the root cause of my problems.
I also need a manual function with a seamless transition, which I'm strugling to do.
As far as I can tell my FC is paramaterized correctly, maybe it's just in need on fine tuning on the PID settings.
Could somebody give me some advise with regard to the best approach in setting up the loop? or maybe an example of a simple PID loop set-up for S7-300. I'm not that experienced in process control, although i understand the basics. Nor am i familur with S7-300 (but I am learning very quickly)!
Any help would be greatly apprciated!
My current settings as follows:
PV - temp in
SP - 32 deg
CV - 0-100% (valve)
Gain - 2.00
TI - 20s
TD - 10s
TM_Lag - 2s
I have never used S7-300 PID control and reading articles on the forum, the standard FC does not get good reviews.
The problem is my valve output is not behaving as expected and thus bounces around, resembling on / off control rathar than an nice smooth PID action. The temperature value (PV) is read over Modbus and only updates every 5 seconds. I can have this wired in as a 4-20mA signal if need be, but the temp change is relativly slow, so I doubt it's the root cause of my problems.
I also need a manual function with a seamless transition, which I'm strugling to do.
As far as I can tell my FC is paramaterized correctly, maybe it's just in need on fine tuning on the PID settings.
Could somebody give me some advise with regard to the best approach in setting up the loop? or maybe an example of a simple PID loop set-up for S7-300. I'm not that experienced in process control, although i understand the basics. Nor am i familur with S7-300 (but I am learning very quickly)!
Any help would be greatly apprciated!
My current settings as follows:
PV - temp in
SP - 32 deg
CV - 0-100% (valve)
Gain - 2.00
TI - 20s
TD - 10s
TM_Lag - 2s
