Why does a SubVI block the main VI's menu bar?

[Justin_Reina]

Why does a background SubVI block menu bar access of the VI which called that SubVI? For clear and simple illustration open A.vi in the attached example code.zip and follow the simple procedure listed on it's Front Panel.

What gives...?

🙂

[Artem.SPb]

You have "lock FP" in your event.
Moreover, B.vi still works, of course, the cycle in A.vi can't go to the next iteration untill B not finished.

[mikeporter]

It is called "dataflow" and it is what makes LabVIEW work. The good news is that there are only two rules that govern its operation.

1. Any node that has all its inputs satisfied will begin execution. This means that LabVIEW code is often inherently parallel.

2. A node will only output data when it finishes executing. This allows you control sequential operations through natural data dependencies, rather than artificial program structures.

Perhaps you need to go through a few tutorials?

Mike...

[PalanivelThiruvenkadam]

If you want launch B.vi as well as want to access A.vi. then try to lauch B.vi Dynamically which will run independent of your A.vi and you can access A.vi