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Chapter 3      Software Overview

© National Instruments Corporation

3-39

NI-VXI User Manual

Figure 3-3 provides a graphical overview of the NI-VXI interrupt and
signal functions.

RouteVXIint()

VXI/VME Interrupts 1-7

VXIintHandlers

SignalHandlers

NI-VXI base Interrupt Service Routines (ISR)

Local VXI Signals

EnableSignalInt()
DisableSignalInt()

RouteSignal()

EnableVXIint()

DisableVXIint()

EnableVXItoSignalInt()

DisableVXItoSignalInt()

SetVXIintHandler()

GetVXIintHandler()

DefaultVXIintHandler()

SignalEnq()

(1 per VXI/VME interrupt level)

(1 per logical address)

SetSignalHandler()

GetSignalHandler()

DefaultSignalHandler()

Signal Processor

Signal Queue

WaitForSignal()

If signal not on queue
  enable monitor
  block till received
else
  SignalDeq()
return signal, mask

SignalDeq()

(uint16)signal

SignalEnq()

SignalDeq()

SignalJam()

(uint16)statusId

WaitForSignal()

(uint16)level, (uint32)statusId

(uint16)signal

(uint16)signal

Get Signal

Get Status/Id

VXIintAcknowledgeMode()

Figure 3-3.  NI-VXI Interrupt and Signal Model

The function 

WaitForSignal

 can be used to suspend a

process/function until a particular VXI signal (or one of a set of
signals) arrives. Any signals to be waited on should be routed to the
global signal queue. If the 

RouteSignal

 function has specified

for the signal to be handled by the interrupt service routine, the

WaitForSignal

 call will not detect that the signal and the

process/function may block until a timeout. 

WaitForSignal

 attempts

to dequeue a signal of the specified type before the process/function is
suspended. If an appropriate signal can be dequeued, the signal is