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Chapter 3      Software Overview

NI-VXI User Manual

3-50

© National Instruments Corporation

queue. The 

RouteSignal

 function specifies which types of signals

should be handled by signal handlers, and which should be queued on
the global signal queue for each VXI logical address. If the VXI/VME
interrupt status/IDs are specified to be handled by a VXI/VME
interrupt handler, the level and status/ID value is sent to the appropriate
callback handler when an interrupt occurs. An individual handler
can be installed for each of the seven VXI/VME interrupt levels.

EnableVXIint

 and 

EnableVXItoSignalInt

 must be used to

sensitize the local CPU to interrupts generated by VXI/VME interrupts.
Only the levels routed to the appropriate handlers (VXI/VME
interrupts or VXI signals) via the 

RouteVXIint

 function are enabled.

SetVXIintHandler

 replaces the current callback handler for the

specified VXI/VME interrupt levels with an alternate callback handler.
If VXI/VME interrupts are enabled (via 

EnableVXIint

), the

VXI/VME interrupt handler for a specific logical address is called.
The 

RouteVXIint

 function must first be called to route VXI/VME

interrupts to the callback handler (as opposed to the signal processing
routine). A default handler, 

DefaultVXIintHandler

 is automatically

installed when the 

InitVXIlibrary

 function is called for every

applicable VXI/VME interrupt level. You can use

SetVXIintHandler

 to install a new callback handler.

VXIintAcknowledgeMode

 specifies whether to handle the VXI/VME

interrupt acknowledge cycle for the specified controller (embedded or
extended) for the specified levels as ROAK interrupts or as RORA
interrupts. If the VXI/VME interrupt level is handled as a RORA
interrupt, the local interrupt generation is automatically inhibited
during the interrupt acknowledgment. After device-specific interaction
has caused the deassertion of the interrupt on the backplane, your
application must call 

EnableVXIint

 to re-enable the appropriate

VXI/VME interrupt level.