Stop a sub VI from main VI

[Skeggy88]

Hi,

I have an application that command a DAQ via tcp.

In the main loop I wait for instruction (listening for new tcp connection) and, if i read a particular string, I start the acquisition using a sub VI.

If I read another string I need to stop the subVI and return a result.
I'm able to do that, but only with a push button (switch when pressed), and I don't understand why it doesn't work with boolean values (in the pentagon: if I read "OF0" I will stop the program)..

I attach an image of my program.
Thanks to all,
Veronica

(The main VI is a modify of Multiple connections - server.vi example.)

[Skeggy88]

Is there anyone?

[Rob_Ward]

Dear Veronica,

Thank you for providing those screenshots of your program.  As a word of advice I wouldn't put while loops or event structures in a sub-vi.  You will run into difficulties such as the ones you describe.  Looking at your code; I think you are making life difficult for yourself with this architecture.

The common use for booleans and event structures are inside a while loop with the boolean control inside the event structure.  If you see Example 1 - RW.vi when the button Generate Data is pressed it returns to it's false state.  Whereas in Example 2 - RW.vi the button has a switch behaviour even though it has a latch mechanical action.

I hope this information is useful.

Kind Regards,

[billko]

---

@Rob_Ward wrote:

Dear Veronica,

Thank you for providing those screenshots of your program.  As a word of advice I wouldn't put while loops or event structures in a sub-vi.  You will run into difficulties such as the ones you describe.  Looking at your code; I think you are making life difficult for yourself with this architecture.

<snip>

---

I disagree.  As long as you really understand event structures and while loops, you are actually making life difficult by NOT placing them in sub-VIs.  But perhaps you meant that those particular structures inside a sub-VI should be as independant as possible from events occuring outside of it?  That would make more sense  :).

[Mark_Yedinak]

Iwould be in some serious trouble if I couldn't put event structures of while loops in subVIs.

[Skeggy88]

Thanks for replies.

I can't open these examples because I have labview 2010.

A practical idea? I hope that what I want to do is possible, because this is a little part of a big project and I hope that I will not have to change everything!

[Skeggy88]

Who said me that is possible, can explain me how?? Please!!

[Skeggy88]

Anyone that can help me??? PLEASE!!
I don't understand why I can stop a while into a subVI with a button (and references) and not with a variable!
I wait for an expert 

[billko]

---

@Skeggy88 wrote:

Anyone that can help me??? PLEASE!!
I don't understand why I can stop a while into a subVI with a button (and references) and not with a variable!
I wait for an expert 

---

I think you will find the tutorials on state machines fascinating reading.  😉

[GregFreeman]

You may want to look at Ben's post here too.