Click Open LabView Screens

LabView VIs are modular in design, so any VI can run by itself or be used as part of another VI. When you place one VI within another, it becomes a subVI of the higher-level VI.

When you add a VI to a higher-level VI, you’ll find the subVI contained in an icon. If you double click on the subVI, you’ll open its front panel, which contains the controls used in the subVI. Sometimes, however, instead of viewing that subVI’s front panel, you’d like to view its data-flow diagram. To do that on a Windows system, hold down the Control key while you double click on the subVI’s icon. (Other operating systems use different keys.1) Figure 1 shows the result.

Figure 1. LabView lets you quickly open the front panel of a subprogram, called a subVI. Use the Control key while opening a subVI to access the data-flow diagram.

A LabView program typically consists of a hierarchy of VIs. Using the hierarchy window, LabView lets you see which VIs call other VIs. Unfortunately, in a large application, the hierarchy window can become rather complex when showing multiple levels. A click of the mouse can traverse this hierarchy and help you keep track of which other VIs call which VIs. Figure 2a shows a relatively simple hierarchy window. Suppose you want to view the hierarchy of only those VIs that call or are called by AI_Waveform_Scan.vi. Click on that VI’s icon while holding the Windows Control key and you’ll see the diagram in Figure 2b. LabView will display only those icons that represent VIs in that flow of data. T&MW

Figure 2. (a--top) The hierarchy of a LabView program. (b--bottom) The VIs associated with AI_Waveform_Scan.vi.

FOOTNOTE
1. For LabView on a Macintosh, use the Option key in place of the Control key. Under Unix, use the Meta key.

Lynda Gruggett is the editor of LabVIEW Technical Resource, an independent publication for LabView Users. lynda_gruggett@ltrpub.com.