Chapter 3
VXI Configuration Utility
3-4
ni.com
Notice that options relating to VXI shared memory are disabled when the
Address Space
option is set to A16. Only if you select A16/A24 or
A16/A32 are the following options relevant:
•
VXI Shared RAM Size
•
Shared RAM Pool
•
Upper/Lower Half Window Byte Swapping
•
Upper/Lower Half Window Address Mapping
VXI Shared RAM Size
This field indicates the amount of RAM (in bytes) that is shared in either
A24 or A32 space. This determines the
total
shared RAM size. Setting this
field to –1 detects how much memory you have installed in your VXIpc
controller and requests the same amount of A24 or A32 space. However,
if you have more than 8 MB installed in your VXIpc, you need to change
the Address Space field to use A32 space.
Shared RAM Pool
This field indicates the size of memory in kilobytes that is allocated on
NI-VXI startup. This is physically contiguous memory that can be
dual-ported on the VXIbus.
The shared RAM pool is used by
VXImemAlloc()
function calls.
For information on the
VXImemAlloc()
function, refer to the
NI-VXI
User Manual
and the
NI-VXI Programmer Reference Manual
.
If you make a change to this setting, you must restart the computer to enable
the change.
Advanced Shared RAM Settings
The VXI shared RAM is divided into two halves, or
windows
. You can
select the byte order and mapping scheme for each half independently.
These configuration options are intended for more advanced users.
Upper/Lower Half Window Byte Swapping
This field indicates whether byte swapping should be performed for slave
accesses to this half of the VXI shared RAM space. For example, if the
Memory Range
Default Value
0 to 65535 KB
0 KB
