Wait on Notification Function

Owning Palette: Notifier Operations Functions

Requires: Base Development System

Waits until a notifier receives a message.

When the notifier receives a message, this function continues to execute. Use the Send Notification function to send the message. If a notifier reference becomes invalid such as when another function closes it, the function stops waiting and returns error code 1122. If the notifier does not contain a message, this function waits until the notifier receives a message.

Details  

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	notifier is a reference to a notifier. Use the Obtain Notifier function to obtain a notifier reference.
	ignore previous indicates whether to ignore messages that LabVIEW sends to the notifier before it calls this function. If TRUE and the notifier contains a message before you call this function, this function waits until the notifier receives another message. If FALSE (default) and the notifier contains a message before you call this function, this function continues to execute.
	timeout in ms specifies the time, in milliseconds, that the function waits for the notifier to receive a message. The default is –1, which indicates never to time out. If the function waits timeout in ms and the notifier does not receive a message, timed out? is TRUE.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	notifier out returns notifier unchanged.
	notification is the last message the notifier receives. This data type changes to match the subtype of notifier.
	timed out? is TRUE if the notifier does not receive a message before the function times out or if an error occurs.
	error out contains error information. This output provides standard error out functionality.

Wait on Notification Details

Each unique instance of this function remembers the timestamp of the last message it receives.

If ignore previous is FALSE, each instance of the Wait on Notification function waits if the message in the notifier has a time stamp for the same time that the instance of the function last executed. If the message is new, then the function returns the message.

When ignore previous is TRUE, the Wait on Notification function always waits for a new message, even if the message currently in the notifier is one it has never seen before.

If you experience deadlock when you use this function repeatedly with different notifiers, use the Wait on Notification with Notifier History function to store timestamps for each individual notifier. This function prevents deadlock.

This function does not remove the message from the notifier. Although a specific instance of the function returns a message only once, other instances of the function or to the Wait on Notification from Multiple function repeat the message until you call the Send Notification function with a new message.