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LabVIEW Programming Reference Manual

Table of Contents
  • LabVIEW Programming Reference Manual
  • Functions
  • Property and Method Reference
  • LabVIEW Environment Reference
  • LabVIEW Dialog Box Reference
  • Error Codes and Messages
Table of Contents

VI Methods

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  • Updated2026-02-04
  • 9 minute(s) read
    • LabVIEW
    • API Reference
    • LabVIEW G

  • Abort VI
    Aborts the execution of a top-level VI.
  • Adapt Nodes
    Allows LabVIEW to replace overloaded nodes with more appropriate implementations. For example, if you script an Add function and wire a Matrix control to it, LabVIEW breaks the wire. If you call Adapt Nodes, the Add function might be replaced with a Matrix Add VI. Operator overloading will not occur during scripting. You must call this method for Overloading to happen.
  • Block Diagram:Clean Up
    Cleans up the block diagram of the VI by rearranging and resizing its objects and signals to improve readability. You also can select Edit»Clean Up Diagram to clean up the block diagram.
  • Block Diagram:Get Image Scaled
    Returns an image of the block diagram and scales it proportionally according to the maximum width and height you wire to the method. For example, if the image of the block diagram is 200 by 200 pixels and you wire a value of 50 to maximum width and a value of 100 to maximum height, this method returns an image that is 50 by 50 pixels. If you do not wire a value to maximum width or maximum height, the image retains its actual size.
  • Block Diagram:Remove Bad Wires
    Removes all the broken wires on the block diagram of the VI.
  • Clear History
    Clears the revision history of the referenced VI.
  • Compile:VI
    Compiles the VI and optionally the entire VI hierarchy of that VI.
  • Configure Panel As Top-Level Hidden
    Hides the front panel of the VI and optionally hides the VI from the taskbar when the VI runs as a top-level VI by changing the VI properties, such as the front panel transparency, run-time position, and minimization properties. This method is useful when you want to control if and when the front panel opens for top-level VIs. For example, use this method to hide the front panel of startup VIs of stand-alone applications that you build in LabVIEW.
  • Control VI Apply Changes
    Apply changes made to a control VI. This method returns an error if used on non-control VIs.
  • Control Value:Get
    Gets the value of a named control or indicator as variant data. Use the Variant to Data function to convert the data to another LabVIEW data type.
  • Control Value:Get All
    Gets the values of all controls or indicators in a VI as variant data. This method returns an array of clusters that contains control and indicator names and their values as variant data. Use the Variant to Data function to convert the data to another LabVIEW data type.
  • Control Value:Set
    Sets the value of a named control or indicator of the variant. You can wire a value of any data type to this method. You do not have to use the To Variant function to convert the data to a variant data type.
  • Create from Data Type
    Creates a control or constant of the data type you specify. LabVIEW always creates a control initially, even if you configure Style to create a constant or indicator. To change the type of the new object, use the Indicator property.
  • Create from Reference
    Creates a constant or control using a constant or control reference as a template.
  • Debugging:Get Debug Button Display State
    Returns TRUE if the button is enabled or FALSE if the button is grayed out. This method also returns the string for the tip strip associated with the button. For example, this method might return Step into For Loop for the Step Into button.
  • Debugging:Step Into
    Single-steps through a VI to help you debug the VI. To use this method, the VI must be paused.
  • Debugging:Step Out
    Single-steps through a VI to help you debug the VI. To use this method, the VI must be paused.
  • Debugging:Step Over
    Single-steps through a VI to help you debug the VI. To use this method, the VI must be paused.
  • Default Values:Make Current Default
    Changes the defaults of all controls on the front panel to be the current values. This method is available only in edit mode.
  • Default Values:Reinitialize All To Default
    Changes the current values of all controls on the front panel to their defaults.
  • Detect Parallel Loops
    Detects parallel loops in the VI.
  • Disconnect From Library
    Disconnects a VI that a LabVIEW project library owns from the owning project library.
  • Empty
    Empties the front panel and block diagram of the VI.
  • Find Control with Key Focus
    Return a reference to the control that currently has key focus. If there is not a control with key focus in the target VI, Not a Refnum is returned.
  • Front Panel:Center
    Specifies whether to automatically center the front panel window on the computer screen.
  • Front Panel:Close
    Closes the front panel window.
  • Front Panel:Get Image
    Returns an image of the front panel as a flattened pixmap. Use the Front Panel:Get Image Scaled method to return an image of the front panel and scale it proportionally according to the maximum width and height you wire to the method.
  • Front Panel:Get Image Scaled
    Returns an image of the front panel and scales it proportionally according to the maximum width and height you wire to the method. This method is similar to the Front Panel:Get Image method.
  • Front Panel:Open
    Opens the front panel window. If the front panel is already open, this method changes the state of the front panel window to the state you wire to this method.
  • Front Panel:Run-Time Position:Centered
    Configures the referenced VI to center its front panel every time the VI runs. If the VI is running when you call this method, the change does not take effect until the next time the VI runs.
  • Front Panel:Run-Time Position:Custom
    Configures the referenced VI to open its front panel in a custom position every time the VI runs. If the VI is running when you call this method, the change does not take effect until the next time the VI runs.
  • Front Panel:Run-Time Position:Get Position
    Returns the default position of the front panel window at run-time.
  • Front Panel:Run-Time Position:Maximized
    Configures a VI to maximize its front panel every time the VI runs. If the VI is running when you call this method, the change does not take effect until the next time the VI runs.
  • Front Panel:Run-Time Position:Minimized
    Sets a VI to minimize its front panel every time the VI runs. If the VI is running when you call this method, the change does not take effect until the next time the VI runs.
  • Front Panel:Run-Time Position:Unchanged
    Configures the VI to maintain the position of its front panel window when the VI runs.
  • Get Compile Metrics
    Returns a string that describes transform metrics from the most recent compile of the VI, if metric recording was enabled.
  • Get Conpane Image
    Returns the connector pane image, as it appears in the Context Help window, as a cluster of image data so you can draw it as a picture using the Draw Flattened Pixmap VI or save the image to a file using the Graphics Formats VIs.
  • Get Control Index by Name
    Gets the index for the control or indicator of the given name. If the control or indicator for which you want to get an index does not have a terminal on the block diagram, this method returns an error.
  • Get Library Access Scope
    Returns the access scope or inherited access scope of this VI if it is owned by a LabVIEW project library. This method provides the same information as the method Source Scope:Get of the Project Library class without requiring a reference to the owning project library.
  • Get ObjectRef From BookmarkID
    Returns a reference to the object, such as the label, that contains the bookmark.
  • Get VI Bookmarks
    Returns the bookmark information for the specified VI reference. You must load the VI into memory in order to read the bookmark information. This method returns an error if the VI is password protected or if the VI does not have a block diagram.
  • Get VI Dependencies (Names and Paths)
    This method returns the names and paths of the VI dependencies of a VI. You can use this method to return a specific subset of the total set of VI dependencies of a VI. This method does not return non-VI dependencies, such as project libraries, XControls, classes, and statecharts.
  • Lock State:Get
    Returns the lock state of the VI and indicates whether the password for the VI is in the password cache.
  • Lock State:Set
    Sets the lock state of a VI. If interactive is FALSE (default), you can use password to either unlock a password-protected VI or set the password of an unprotected VI. If interactive is TRUE, LabVIEW ignores password and displays a dialog box that prompts you to change the lock state.
  • Move Objects
    Moves the objects by the offset amount of pixels.
  • Pause VI
    Pauses or unpauses the VI execution.
  • Populate Asynchronous Call Pool
    Ensures that the asynchronous call pool for a VI reference contains at least the number of data spaces specified by the Minimum Size parameter. By default, when you open a reference with the Open VI Reference function, LabVIEW allocates one data space per CPU core on the development computer.
  • Print:Panel To PostScript
    Prints the panel of the VI to the specified PostScript file.
  • Print:Panel To Printer
    Prints just the front panel to the current printer. You cannot use this method to print a block diagram, list of controls, or polymorphic VI front panel.
  • Print:VI To HTML
    Saves the VI information to an HTML file and saves the graphics in external files. You can use the Open URL in Default Browser VI to display the HTML file in the default Web browser.
  • Print:VI To Printer
    Prints the VI information to a printer.
  • Print:VI To RTF
    Saves the VI information to an RTF file.
  • Print:VI To Text
    Saves the VI information to a text file. You cannot save the icon, connector pane, front panel, block diagram, subVI icons, and VI hierarchy to text.
  • Remote Panel:Client Connections
    Returns an array of clusters containing connection information about the clients viewing or controlling the VI.
  • Remote Panel:Close Connection To Client
    Closes a remote front panel connection to a client.
  • Remote Panel:Lock Control
    Returns control of the front panel to the server and queues any requests from clients to control the front panel. LabVIEW ignores this method if the front panel is already locked.
  • Remote Panel:Unlock Control
    If the front panel is locked, this method grants control to the next client in the queue. If no clients are in the queue, the method unlocks the front panel. LabVIEW ignores this method if the front panel is already unlocked.
  • Replicate Conpane
    Make the connector pane of the VI Reference match the given connector pane.
  • Revert VI
    Discards changes and reloads a VI from disk.
  • Run VI
    Starts the VI execution, similar to the Run button. This method is different than calling a VI because it uses the current values of all front panel controls for execution rather than using data passed in through parameters. This method also ignores the Execution:Show Front Panel On Call property of a VI and the Execution:Close After Call property.
  • Save:For Previous
    Saves a copy of the VI that is readable by LabVIEW version 8.0 and later. If you save a password-protected VI for a previous LabVIEW version, you must enter the password. You can enter the password programmatically as an input on the Open VI Reference function.
  • Save:Instrument
    Saves a VI that is not currently running and synchronizes the VI with the edited version in other application instances before saving.
  • Save:Run-Time Menu
    Saves the run-time menu to a file specified by Path. This method works only when the VI is running. It saves only menu items with valid tags.
  • Transaction:Begin Undo
    Begins an undo transaction on a VI.
  • Transaction:End Undo
    Ends an undo transaction on a VI.
  • Transaction:Fail
    Fails the current transaction and deletes the undo information for the transaction.
  • Transaction:Get Redo State
    Returns whether there is an action to redo and, if so, the text that corresponds to that action.
  • Transaction:Get Undo State
    Returns whether there is an action to undo and, if so, the text that corresponds to that action.
  • Transaction:Redo
    Redoes the last operation. This is similar to selecting Edit»Redo.
  • Transaction:Undo
    Undoes the last operation. This method is similar to selecting Edit»Undo.
  • VI Icon:Get As Image Data
    Returns the VI icon as a cluster of image data so you can draw it as a picture using the Draw Flattened Pixmap VI or save the image to a file using the Graphics Formats VIs.
  • VI Icon:Save To File
    Saves an image of the VI icon to a file.
  • VI Icon:Set From File
    Sets the image of a VI icon from a file. LabVIEW creates a user layer called VI Icon for the image and deletes any other existing icon information from the Icon Editor dialog box.
  • VI Icon:Set From Image Data
    Sets a VI icon from image data you specify. LabVIEW creates a user layer called VI Icon for the image and deletes any other existing icon information from the Icon Editor dialog box.
  • VI Strings:Export
    Exports the following strings about VI and front panel objects to a tagged text file: VI name and description, object caption labels, object free labels, default data (string, table, path, and array default data), private data (listbox item names, table row and column headers, graph plot names, graph cursor names, graph annotation names, and tab control page captions), and polymorphic VI data (instance names in the polymorphic VI and selector shortcut menus).
  • VI Strings:Import
    Imports the following strings about VI and front panel objects from a tagged text file: VI name and description, object caption labels, object free labels, default data (string, table, path, and array default data), private data (listbox item names, table row and column headers, graph plot names, graph cursor names, graph annotation names, and tab control page captions), and polymorphic VI data (instance names in the polymorphic VI and selector shortcut menus).

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