A subVI is the LabVIEW equivalent to “functions,” “subroutines,” and “methods” in other programming languages. You can easily create a subVI that can be used reused many times in other VIs; editing the subVI one time updates its behavior for all VIs that use the subVI, which simplifies program design and maintenance. Moreover, the subVI forms the basic method by which you can create a hierarchical program.
The screencast video below details the necessary steps to convert a conventional block diagram into a subVI by adding a connector pane and an icon . These two elements enable the block diagram to appear as an element on another block diagram with a connection pattern specific to the requirements of the task performed by the subVI. In addition, you can set the VI Description (part of the VI Properties ) of your subVI so that hovering your cursor over your subVI reveals a helpful description of its behavior.