Synchronize to Scan Engine VI

NI Scan Engine VIs

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Installed With: RT Module

Synchronizes execution timing to the scan period of the NI Scan Engine. This VI waits for each scan to complete and triggers subsequent code to execute once the scan engine has updated all values.

Use the Scan Engine page of the RT Target Properties dialog box to configure the scan period. You also can use the Set Scan Engine Period VI to set the scan period programmatically.

Details Example

Place on the block diagram

Find on the Functions palette

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 occurred 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 exception control to treat what is normally an error as no error or to treat a warning as an error. 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.

	status is TRUE (X) if an error occurred before this VI or function ran or FALSE (checkmark) to indicate a warning or that no error occurred before this VI or function ran. The default is FALSE.
	code is the error or warning code. The default is 0. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
	source specifies the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning. The default is an empty string.

scans since last call returns the number of times the scan engine has completed a scan since the last call of this VI. You can use this information to identify missed scan iterations and determine whether the synchronized code consistently finishes executing on time.

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 front panel indicator and select Explain Error from the shortcut menu for more information about the error.

	status is TRUE (X) if an error occurred or FALSE (checkmark) to indicate a warning or that no error occurred.
	code is the error or warning code. If status is TRUE, code is a nonzero error code. If status is FALSE, code is 0 or a warning code.
	source describes the origin of the error or warning and is, in most cases, the name of the VI or function that produced the error or warning.

Synchronize to Scan Engine Details

Use this VI for code running outside of a timed structure. For most NI Scan Engine use cases, NI recommends using a timed structure with the Synchronize to Scan Engine timing source.

This VI must run on a target with the NI Scan Engine installed.

Example

Refer to the Scan Engine.lvproj in the labview\examples\scanengine directory for an example of using the Synchronize to Scan Engine VI.

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