An Express VI consists of the following components:

• Configuration dialog box VI —Allows users to configure settings for the run-time behavior of the Express VI.
• Source VI —Contains the code for the Express VI. The source VI also contains a link to the configuration dialog box VI.

When you place an Express VI on the block diagram, a configuration dialog box appears. The configuration dialog box VI determines the appearance and functionality of this configuration dialog box. After you configure the Express VI and close the configuration dialog box, the Express VI appears as an expandable node on the block diagram. You can set the inputs and outputs of the expandable node. However, you cannot double-click the expandable node to open it and see the underlying front panel and block diagram as you can do with a subVI. You must convert the Express VI to a subVI in order to view the underlying code. The underlying code of the Express VI is determined by the source VI. After you convert an Express VI to a subVI, you no longer can access the configuration dialog box or convert the subVI back to an Express VI.

You must design both the configuration dialog box VI and the source VI for any Express VI you create.

To create and distribute an Express VI, you must complete the following stages of development.

• Design the source VI for the Express VI.
• Design the configuration dialog box, including the user interface.
• Associate help files with the Express VI.
• Place the Express VI in the LabVIEW directory structure.
• Add the Express VI to a new or existing palette.

When you add an Express VI to the labview\user.lib\_express directory, the Express VI appears on the Express User Libraries palette. A paletteMenu subpalette appears for each LLB or directory in the labview\user.lib\_express directory that does not start with an underscore. As a result, both the Express VI and the subVI of the source VI appear on the palette.

You can edit the palettes to display only the Express VIs and to remove additional layers of subpalettes so the Express VIs are easier to access. You can edit custom palette views with Express VIs in the same way you edit palettes with other objects.

Note When you place an Express VI on a palette, the blue box around the icon might appear to be missing. However, after you save changes to the palette, the Express VI looks correct.