Справочник Пользователя для National Instruments NI-VXI

Chapter 3      Software Overview

NI-VXI User Manual

3-42

© National Instruments Corporation

SignalDeq

 retrieves signals from the global signal queue. Two

methods are available to handle VXI signals. You can handle the
signals either by handlers or by queueing on a global signal queue. The

RouteSignal

 function specifies which types of signals should be

handled by which of the two methods for each VXI logical address.
You can use 

SignalDeq

 to selectively dequeue a signal off of the

global signal queue. The signal specified by signalmask for the
specified logical address (la) is dequeued and returned in the output
parameter signal.

SignalEnq

 places signals at the end of the global signal queue. You

can use 

SignalEnq

 within a signal handler to queue a signal or to

simulate the reception of a signal by placing a value on the global
signal queue that was not actually received as a signal.

SignalJam

 places signals at the front of the global signal queue.

SignalJam

 can be used to simulate the reception of a signal by

placing a value on the global signal queue that was not actually
received as a signal. Because 

SignalJam

 places signal values on the

front of the global signal queue, the signal is guaranteed to be the first
of its type to be dequeued.

WaitForSignal

 waits for the specified maximum amount of time for

a particular signal (or class of signals) to be received. 

Signalmask

defines the type(s) of signals that the application program waits for.
The timeout value specifies the maximum amount of time (in
milliseconds) to wait until the signal occurs. The signal that unblocks
the 

WaitForSignal

 call returns in the output parameter retsignal.

You should use the 

WaitForSignal

 function only when signals are

queued. A multitasking operating system lets you have any number of

WaitForSignal

 calls pending. A non-multitasking operating system

permits only one pending 

WaitForSignal

 call.