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Chapter 3      Software Overview
© National Instruments Corporation
3-47
NI-VXI User Manual
Normally, VXI/VME interrupts are automatically acknowledged when
enabled via the function 
EnableVXIint
. However, if the interrupts
are not enabled and the assertion of an interrupt is detected through
some method (such as 
GetVXIbusStatus
), you can use
AcknowledgeVXIint
 to acknowledge an interrupt and return the
status/ID value. If the controller parameter specifies an extended
controller, 
AcknowledgeVXIint
 specifies hardware on the VXI/VME
frame extender (if present) to acknowledge the specified interrupt.
  AssertVXIint (controller, level, statusId)
AssertVXIint
 asserts a particular VXI/VME interrupt level on a
specified controller (embedded or extended) and returns the specified
status/ID value when acknowledged. You can use 
AssertVXIint
 to
send any status/ID value to the VXI/VME interrupt handler configured
for the specified VXI/VME interrupt level. 
AssertVXIint
 returns
immediately (that is, it does not wait for the interrupt to be
acknowledged). You can call 
GetVXIbusStatus
 to detect if the
interrupt has been serviced. Use 
DeAssertVXIint
 to unassert a
interrupt that had been asserted using 
AssertVXIint
 but has not yet
been acknowledged.
  DeAssertVXIint (controller, level)
DeAssertVXIint
 unasserts the VXI/VME interrupt level on a given
controller that was previously asserted using the 
AssertVXIint
function. You can use 
AssertVXIint
 to send any status/ID value to
the VXI/VME interrupt handler configured for the specified interrupt
level. You can call 
GetVXIbusStatus
 to detect if the interrupt has
been serviced. Use 
DeAssertVXIint
 to unassert a VXI/VME
interrupt that had been asserted using 
AssertVXIint
 but has not yet
been acknowledged.
Note:
Unasserting an interrupt may violate the VME and VXIbus specifications
if the interrupt has not yet been acknowledged by the interrupt handler.
  DefaultVXIintHandler (controller, level, statusId)
DefaultVXIintHandler
 is the sample handler for VXI/VME
interrupts, which is installed when the function 
InitVXIlibrary
 is
called. If VXI/VME interrupts are enabled (via 
EnableVXIint
), the
VXI/VME interrupt handler for a specific logical address is called. You
must first call 
RouteVXIint
 to route VXI/VME interrupts to the
callback handler (as opposed to the signal processing routine).