Calls the VI specified by reference. The reference VI must be a strictly-typed reference. Both Call By Reference Node and subVI node call a VI. Call By Reference Node enables you to call any VI whose connector pane matches that of the strictly-typed reference input. Strictly-typed references can be obtained from the Open VI Reference function. A subVI node only allows you to call a specific VI that is statically determined when you drop the subVI node on the diagram. Details
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reference is the refnum associated with a VI that is already open. | ||||||
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error in describes error conditions that occur before this VI or function runs.
The default is no error. If an error occurred before this VI or function runs, the VI or function passes the error in value to error out. This VI or function runs normally only if no error occurs before this VI or function runs. If an error occurs while this VI or function runs, it runs normally and sets its own error status in error out. Use the Simple Error Handler or General Error Handler VIs to display the description of the error code. Use error in and error out to check errors and to specify execution order by wiring error out from one node to error in of the next node.
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dup reference returns reference unedited. | ||||||
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error out contains error information. If error in indicates that an error occurred before this VI or function ran, error out contains the same error information. Otherwise, it describes the error status that this VI or function produces.
Right-click the error out indicator on the front panel and select Explain Error from the shortcut menu for more information about the error.
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At the top of the Call By Reference Node are four terminals: an input/output pair of flow through VI reference terminals and an input/output pair of flow through error clusters. The VI reference input accepts wires only from strictly typed VI references. Below these terminals is an area within which a connector pane resides that is identical to that of a VI with its terminals showing (rather than its icon). The connector pane of the strictly typed VI reference input determines the pattern and data types of this connector pane. Wire to these terminals just as you would to a normal subVI.
Refer to the Flow-Through Parameters section of Chapter 11, Reading from and Writing to Files in the LabVIEW User Manual for a complete description of flow-through parameters.
If none of the terminals of the connector pane have wires attached to them, the connector pane adapts automatically to that of the input VI reference's connector pane. However, if any of them are wired, the node does not adapt automatically, and you must explicitly change the connector pane (possibly breaking those wires) by right-clicking the node and selecting Adapt To Reference Input from the shortcut menu.
At run time there is a small amount of overhead in calling the VI that is not necessary in a normal subVI call. This overhead comes from validating the VI reference and a few other bookkeeping details. However, for a call to a VI in the local instance of LabVIEW, this overhead should be insignificant for all but the smallest subVIs. Calling a VI located in another LabVIEW application (across the network) involves considerably more overhead.