Hello Expert,

Usually i program PID to control analog modulator valve using analog output signal from PLC.
Now, i have a case which is the target device that need to control is forward - reverse motorized valve. The motorized valve have 2 contact input which are one for forward signal (open signal) and the another one is reverse signal (close signal). So, it needs use DO (digital output) from PLC to control.
The motorized valve also have 2 limit for 0% close and 100% open.
Then, i need to program the motorized valve to control hot air flow according to the system temperature and i need to maintain the temperature.
My question are :
1. can i program the forward - reverse motorized valve using PID on S7-1200 PLC and instruct the PLC digital output?
2. i need to show out the percentage of that motorized valve position (opened how many percentage).

Please advice.
Thank You.

Regard,
Jhony

jacek d

Ad. 1 - example

Ad. 2 - get an angle encoder for the valve

 Thank you very much Jacek

jacek d

Ad. 1 - example

Ad. 2 - get an angle encoder for the valve

 Dear Jacek,

 I have tried to use PID 3 Step to control the PID for motorized forward - reverse valve, and i want to thank you because it works.
But, i found out one problem, which is :
when the open valve working, the scaled feedback calculate percentage of opening valve.
for example now the opening percentage was 40%.
if the PLC power loss and get back again, the opening percentage become 0%, but the actual on that valve still opening 40%, right?

My question is how to retain the scaled feedback value although the PLC power loss?

Thank You