Hi bt1060,

If I read your post correctly you are expecting that PV_Out will directly be influenced by SP_Ext.
The PV_Out is just a copy of the input parameter PV.
Does the input parameter PV changes?

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The goal of the PID is indeed that the PV will follow the SP but by changing the MV control output.

Example:

Flow in piping controlled via an analog valve (0%=closed, 100%=open)
Start position:
SP = 75 m3/h; PV = 0 m3/h; MV = 0%

Effect:
the PID controller will adjust the MV until the PV meets the SP, so the valve must be opened to get flow, but not to much because then there will be to much flow.

Simplified:
SP<PV >> MV will go down
SP=PV >> MV will be held
SP>PV >> MV will go up

Hope I get your question right, and this will help

Hi bt1060,

by the PIDConL block the output PV_Out ist exactly the same value als PV. The output SP shows the active setpoint. So in your case you find at PV_Out the process value 34.8°C and at the output SP is the active setpoint 35°C (because SP_Ext := 35, SP_LiOp := 1, SP_ExtLi := 1).

More Information about the inputs and outputs of the PIDConL block you can find in the manual PCS 7 Advanced Process Library at section PIDConL I/Os.

With regards
Heisenberg