National Instruments NI-VXI - Manual (Page 95)

Chapter 3 Software Overview
© National Instruments Corporation 3-57 NI-VXI User Manual
crosspoint switch configurator (depending on the hardware capabilities
of the applicable device).
UnMapTrigToTrig (controller, srcTrig, destTrig)
UnMapTrigToTrig unconfigures triggering hardware that was
configured by the MapTrigToTrig function to route specified source
trigger locations to destination trigger locations.
Source Trigger Functions
The NI-VXI source trigger functions act as a standard interface for
asserting (sourcing) TTL and ECL triggers, as well as for detecting
acknowledgments from accepting devices. These functions can source
any of the VXI-defined trigger protocols from the local embedded
controller or external extended controller(s). You can use the
SrcTrig
function to initiate any of the trigger protocols. If the protocol requires
an acknowledgment and your application is required to know when the
acknowledgment occurs, you must use the
SetTrigHandler function
to install a callback handler for the specified trigger line. A default
handler,
DefaultTrigHandler , is installed for each one of the
trigger lines when InitVXIlibrary is called. You can use the
SetTrigHandler function at any time to replace the default handlers.
SrcTrig (controller, line, prot, timeout)
Use SrcTrig to source any one of the VXI-defined trigger protocols
from the local CPU or from any remote frame extender device
that supports trigger assertion. For protocols that require an
acknowledgment from the accepting device (ASYNC or SEMI-SYNC),
you need to specify whether to wait for an acknowledgment (with a
timeout) or return immediately and let the trigger handler get called
when the acknowledgment is received. Another option is available in
which you can assert or unassert any of the trigger lines continuously,
or have an external trigger (possibly from the front panel) routed to the
VXIbus backplane.