Table Of Contents

Preview Queue Element (G Dataflow)

Version:
    Last Modified: March 15, 2017

    Returns the element at the front of the queue without removing the element from the queue.

    If the queue becomes invalid because the queue reference is released, this node stops waiting and returns an error.

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    Note  

    To return and remove the element from the queue, use Dequeue Element instead.

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    queue

    A reference to a queue.

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    timeout in milliseconds

    The number of milliseconds that the node waits for an element to become available in the queue if the queue is empty.

    If an element becomes available in the queue during the wait, the node removes and returns the element and does not time out.

    Default: -1 — The node never times out.

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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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    queue out

    Reference to the queue.

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    element

    A copy of the element at the front of the queue.

    The data type of this output changes to match the data type of the queue elements.

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    timed out?

    A Boolean value that indicates whether an element became available in the queue before the node timed out or if an error occurred.

    True An element did not become available before the node timed out or this node generated an error.
    False An element did become available before the node timed out or an error occurred before this node executed.
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    error out

    The node produces this output according to standard error behavior.

    This node can return the following error codes.

    1122 The reference became invalid while the node was waiting for it.
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    Note  

    This is not a comprehensive list of errors this node can return.

    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


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