Table Of Contents

Obtain Semaphore Reference (G Dataflow)

Last Modified: December 18, 2017

Obtains a reference to an existing semaphore or creates a new semaphore and returns a reference to that semaphore.

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name

The name of the semaphore you want to look up or create. If you wire name, the node searches for an existing semaphore with the same name and returns a unique reference to the existing semaphore. If a semaphore with the same name does not already exist and create if not found is True, the node creates a new, named semaphore and returns a unique reference to that semaphore.

Default: Empty string

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size

The number of tasks that can acquire the semaphore at the same time. If a named semaphore already exists, wiring a value to this input does not resize the semaphore. size must be greater than or equal to 1.

Default: 1

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create if not found

A Boolean that specifies whether you want to create a new semaphore if one with that name does not exist. If create if not found is False and the node cannot find a semaphore with the name you specify, the node returns error code 1534.

Default: True

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error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

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semaphore

A reference to an existing or newly created semaphore. If you use this node to obtain multiple references to the same named semaphore, each reference number is unique.

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created new

A Boolean that returns True if the node created a new semaphore.

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error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Where This Node Can Run:

Desktop OS: Windows

FPGA: This product does not support FPGA devices

Web Server: Not supported in VIs that run in a web application


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