In order to run a VI, LabVIEW must translate, or compile, the code of the VI into a form that the LabVIEW Runtime Engine can execute. After you make certain changes to the VI, LabVIEW must eventually recompile the code. However, because compilation requires time and memory, LabVIEW does not immediately recompile the code while you edit the VI. Instead, LabVIEW recompiles the VI the next time you perform one of the following actions:

• Saving the VI
• Running the VI
• Building an application that requires the VI
• Deploying the VI to a real-time operating system
• Loading a VI last saved in a previous version of LabVIEW or on a different platform.
  Note When you install an old LabVIEW toolkit for use with the current version of LabVIEW, LabVIEW automatically recompiles the toolkit VIs even before you load them.

Changes That Require LabVIEW to Recompile a VI

LabVIEW marks a VI as needing recompilation when you perform one of the following actions:

• Modifying the block diagram
• Adding a control or indicator
• Modifying the appearance of a control or indicator. However, changing the value of a control does not require LabVIEW to recompile the VI.
• Changing certain properties of the VI in the VI Properties dialog box
• Changing a subVI in a way that requires LabVIEW to recompile the subVI. If you separate compiled code from the VI or the subVI, these changes do not require LabVIEW to recompile the VI.
• Programmatically performing any of the above actions

Related Information

Effects of Code Complexity on Compile Time

Choosing between Editor Responsiveness and VI Execution Speed

Separating Compiled Code from a File