Finding the Top Level VI of a LabVIEW Application

Updated Oct 27, 2023



  • LabVIEW
  • LabVIEW Real-Time Module

I got a huge LabVIEW application I did not design and I would like to know what is the Top-Level or main VI. The application is organized by a LabVIEW Project file.

The Top-Level VI is the file that calls all the other subVIs and references, and it is not called by any other VI. To determine what is the Top-Level VI you can use the VI Hierarchy View of LabVIEW, to find the VI that is not called by any other one. To access the VI Hierarchy open the VI you suspect could be the main VI that is within the LabVIEW Project Explorer and go to View>>VI Hierarchy.

Depending on the Application type you are developing you will find the Top-Level VI just under your computer Level if it does not involve any Real-Time Target. Or under the Real-Time target level if you are using a device like a CompactRIO or a PXI Controller.

Under your Computer

Under your Real-Time Target

Additional Information

If you open the VI Hierarchy in a SubVI, you will find that the Top-Level VI is located above this SubVI.