Running VIs

LabVIEW 2013 Help

Edition Date: June 2013

Part Number: 371361K-01

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Running a VI executes the operation for which you designed the VI. You can run a VI if the Run button on the toolbar appears as a solid white arrow, shown as follows.

The solid white arrow also indicates you can use the VI as a subVI if you create a connector pane for the VI.

A VI runs when you click the Run or Run Continuously buttons or the single-stepping buttons on the block diagram toolbar. While the VI runs, the Run button changes to a darkened arrow, shown as follows, to indicate that the VI is running.

You cannot edit a VI while the VI runs.

Clicking the Run button runs the VI once. The VI stops when the VI completes its data flow. Clicking the Run Continuously button, shown as follows, runs the VI continuously until you stop it manually.

Clicking the single-stepping buttons runs the VI in incremental steps.

Note   The Abort Execution button stops the VI immediately, before the VI finishes the current iteration. Aborting a VI that uses external resources, such as external hardware, might leave the resources in an unknown state by not resetting or releasing them properly. Design VIs with a stop button to avoid this problem.

Configuring How a VI Runs

Select File»VI Properties and select Execution from the Category pull-down menu to configure how a VI runs. For example, you can configure a VI to run immediately when it opens or to pause when called as a subVI. You also can configure the VI to run at different priorities. For example, if it is crucial that a VI runs without waiting for another operation to complete, configure the VI to run at time-critical (highest) priority.

Note  Incorrectly configuring a VI to run at different priorities can cause unexpected execution. You do not need to configure most VIs to run at different priorities.

If you do not want a VI to run immediately, but you also do not want users to be able to edit the VI, you can change the VI to run mode by selecting Operate»Change to Run Mode. In run mode, all front panel objects have an abridged set of shortcut menu items. Users can access only front panel controls, toolbar buttons that run and stop the VI, and the menu bar. To allow editing again, select Operate»Change to Edit Mode.


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