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Address Space
Number of MITE Windows
Memory for Allocating Data Structures
MITE DMA
© National Instruments Corporation
The VXI-8340 series can decode any 32-bit address on the PCI bus as a
VXI cycle, giving 4 GB of addressability, which can be used for windows
on the VXI-8340 series. The operating system or computer architecture
may limit which addresses can be assigned to the VXI-8340 series.
To change the address space, edit the User window size field in the PCI
tab of the VXI-8340 series Hardware Configuration settings in MAX.
This setting limits the total amount of memory you can map with
or
MapVXIAddress()
the
MapVXIAddress()
The NI-VXI online help implies that the error code
is returned when the window is in use. Because the MITE-based products
have multiple hardware windows of variable size, the meaning of this
error has been modified.
MAP_TIMEOUT (-8)
window.
For example, if you use
to request a 1 MB window to A32 space, and you request a User Window
in MAX of only 64 KB,
because there are not enough resources to complete the
MAP_TIMEOUT
request.
The MITE has eight CPU windows. NI-VXI uses four of these windows,
leaving four for user applications.
You need to have sufficient memory available for the operating system
to set up its necessary page tables. If you request a very large user
window—hundreds of megabytes, for example—you may run out of
memory.
The MITE has two DMA channels to improve the throughput of block
transfers to and from the VXI system. The DMA channels can use various
high-speed bus protocols, such as the following:
•
Burst mode (on the PCI bus)
•
VME64 (on the VXI bus)
Chapter 3
. If the User Window is disabled,
viMapAddress()
function returns
NO_HARDWARE_SUPPORT (-1)
MapVXIAddress()
whenever there are not enough resources to map the
MapVXIAddressSize()
MapVXIAddress()
3-7
Developing Your Application
MAP_TIMEOUT (-8)
now returns the error code
and
MapVXIAddress()
returns the error code
VXI-8340 Series User Manual
.
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