National Instruments NI-VXI - Manual (Page 21)

Chapter 2 Introduction to the NI-VXI Functions
NI-VXI User Manual 2-2 © National Instruments Corporation
• Low-Level VXIbus Access Functions—Low-level VXI/VMEbus
access functions are the fastest access method for directly reading
from or writing to any of the VXI/VMEbus address spaces. You
can use these functions to obtain a pointer that is directly mapped to
a particular VXI/VMEbus address. Then you use the pointer with
the low-level VXI/VMEbus access functions to read from or write
to the VXI/VMEbus address space. When using these functions in
your application, you need to consider certain programming
constraints and error conditions such as bus errors (BERR*).
• Local Resource Access Functions—Local resource access functions
let you access miscellaneous local resources such as the local CPU
VXI register set, Slot 0 MODID operations (when the local device
is configured for Slot 0 operation), and the local CPU VXI Shared
RAM. These functions are useful for shared memory type
communication, for the non-Resource Manager operation (when the
local CPU is not the Resource Manager), and for debugging
purposes.
• VXI Signal Functions—VXI signals are a method for VXI bus
masters to interrupt another device. You can route VXI signals to a
handler or queue them on a global signal queue. You can use these
functions to specify the signal routing, install handlers, manipulate
the global signal queue, and wait for a particular signal value (or set
of values) to be received.
Note: Although signals are defined in the VXI specification, VME customers
may still use the signal register available on any VXI/VME/MXI
hardware. This register provides a simple notification mechanism that can
be used by any bus-master.
• VXI/VME Interrupt Functions—By default, interrupts are processed
as VXI signals (either with a handler or by queuing on the global
signal queue). The VXI/VME interrupt functions can specify the
processing method and install interrupt service routines. In addition,
the VXI/VME interrupt functions can assert specified VXI/VME
interrupt lines with a specified status/ID value.
• System Interrupt Handler Functions—The system interrupt handler
functions let you install handlers for the various system interrupt
conditions. These conditions include Sysfail, ACfail, bus error, and
soft reset interrupts.
• VXI/VMEbus Extender Functions—The VXI/VMEbus extender
functions can dynamically configure multiple-mainframe mappings