3 Position Valve

Hi All

I have a standard solenoid operated valve which I am using VlvL block to control.  However the valve has two open limit switches used under different plan conditions.  I am hoping to be able to switch between the inputs depending on these plant conditions to allow minimum deviation from my CMTs.

However I can work out a way to switch the input to the valve block.  I have trier having two DiIn blocks and switching the output using a SEL but the output of the SEL does not carry through the structure so wont connect the the feedback input on the VlvL block.  I have also tried having one DiIn block with the SEL block switcheg the raw inputs but again the output of the SEL block wont connect to the PV_In of the DiIn.

Can anyone point me in the right direction?

Thanks

Hello AdamDPS,

you can use the block StruDiIn to separating a binary process value into a variable of the BOOL data type and signal status. So you can connect the SEL input.

Note:
If you use PCS 7 V9.0 or higher you don't have to use the blocks

• StrgToBy - String in byte structure (Struct of Byte)
• StruDiOu - Creating a digital structured variable
• StruDiIn - Separating a digital structured variable
• StruAnOu - Creating an analog structured variable
• StruAnIn - Separating an analog structured variable

With regards
Heisenberg

Dear AdamDPS,

I hope i understand your question correctly. You mentioned SEL block doesnt carry structure in the output. Are you using the SEL block in APL library named SelDiIn(sth like this)? There are all able to carry signal status.

Thanks all.  Sorry for the late update but I have only just returned to this. 

In the end I managed to simplify the selection and use two OR block to which I was able to connect the inputs and the output of one OR block connected to the valve block as the selected feedback signal.