After you build a VI, you can call it from the diagram of another VI within the same project. A VI called from the diagram of another VI is a subVI. SubVIs contain reusable code and simplify the diagrams of calling VIs. SubVIs are analogous to functions or subroutines in other programming languages.
When you add an instance of a subVI to the diagram of another VI, the subVI appears as a single node, similar to a node from the palette. When data in the calling VI reaches the subVI node, the software executes the diagram of the subVI.
The following diagram shows two common situations that benefit from subVIs.
The following diagram shows two solutions that subVIs provide.