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Wait On Occurrence (G Dataflow)

Last Modified: March 15, 2017

Waits for Trigger Occurrence to trigger the specified occurrence and indicates whether the node timed out before the occurrence is triggered.

Programming Patterns

Use the output of this node to control execution of code that you want to execute after you trigger the occurrence.

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timeout in milliseconds

The number of milliseconds that the node waits for the occurrence before timing out.

Default: -1 — This node never times out unless the occurrence is invalid.

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occurrence

A reference to an occurrence.

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ignore previous

A Boolean that determines whether this node ignores the previous trigger of this occurrence.

True If another node has triggered the occurrence before this node executes, this node ignores the previous trigger and waits for another one.
False If another node has triggered the occurrence before this node executes, this node does not wait.

Default: True

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timed out

A Boolean value that indicates whether the node timed out before an occurrence occurred.

True An occurrence did not occur before the node timed out or the occurrence is invalid. If the occurrence is invalid, the node immediately returns True for timed out even if the node is set to never time out.
False An occurrence did occur before the node timed out and the occurrence is valid.

When to Use Occurrences

Occurrences are the most fundamental part of all synchronization mechanisms. You should use occurrences only when no other synchronization method is sufficient. For most operations, you can use the Notifier nodes in place of Occurrence nodes.

Occurrence nodes control separate, synchronous activities without polling. For example, use these nodes when you want one VI or subdiagram to wait until another VI or subdiagram finishes a task without using the processor resources that polling consumes while waiting. Occurrences do not add processor overhead because the waiting VIs or subdiagrams become idle while they wait. When the first VI or subdiagram triggers the occurrence, it also activates the VIs or subdiagrams that wait for the specified occurrence.

Where This Node Can Run:

Desktop OS: Windows

FPGA: This product does not support FPGA devices


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