Valve controls

[KRAZE4LV]

Hello,

I am using Automatic valve with Digital Output and Pressure transmitters with Analog inputs

Logic is

The charging of air pressure is done in the pipes

 Initially the Bypass valve is open and equalize the pressure in PT 1 and PT2 when the pressure in PT1 and PT2 is equal then Bypass valve closed and main air valve is open

If the pressure on PT 3 is above 20bar or below 5bar then the Vent valve should be open,

How can I put the conditions? for valve opening/closing with respect to PT?

Please give some suggestion. please see the attached.

[KRAZE4LV]

I just changed the logic checked with the analog output connections. My VI is working well but actually I wish the Main air valve should continue to be open until the PT1=PT2 continously, but it just blinks and stop. How can put the condition that the valves should continously be open until the condition is changed?

Please see the VI.

Do give some suggestion.

[SercoSteveB]

Can you post LabVIEW 2009 VI?

[GerdW]

Hi Kraze,

what do you want to achieve with that sequence structure?

- It runs in parallel with the rest of the loop...

- It runs much faster than the rest of the loop setting bits in microseconds...

- Due to running in parallel you just created race conditions...

Use some shift registers to keep previous values as is recommended in the basics course!

[FraggerFox]

I can see that in sequence structure frame 0, you are setting the main valve value to FALSE.

I didn't understand what is the purpose of putting a sequence structure inside the while loop....??

[KRAZE4LV]

Hello,

Thanks for the replies.

Actually still I am unable to achieve, the conditions:

1. Main air valve is closed, Vent valve is closed, Bypass is ooen

2. PT1=PT2 the Bypass close and main air valve open

3. If the PT1=300bar the Vent vlave open.

I am also sending the VI in LV 2009 as asked.

[KRAZE4LV]

I just changed the VI with shift register but i dont understand how can it satisfy the conditions.

Please see the attached and suggest.

[Wayne.C]

KRAZE4LV,

It sounds like you need a state machine designed to do something like the attached flow diagram. 

[KRAZE4LV]

Yes Wayne.C thats the actual logic I want...

1.I made with stacked sequence its working but the valve just switch on and off but I want it should stay until the condition is changed.

2. I used cased case strcuture with shift register and while loop but still the condition is not met...

[Wayne.C]

KRAZE4LV,

A stacked sequence will never give the functionality that you need.  You need to design a State Machine.  Suggest you start with the State Machine tutorials on the NI website.