National Instruments VXI-1394 - Manual (Page 28)

Chapter 3 Developing Your Application
© National Instruments Corporation 3-7 VXI-1394 User Manual for Windows
Table 3-1 summarizes the topics the example programs address. All files
are in the
VXIpnp\WinNT\NIvisa\Examples directory, in the
subdirectories listed below.
Note MAX includes configuration options that affect low-level functions and shared
memory, as well as trigger mappings and other attributes of your VXI system. Refer to the
MAX online help for information regarding these options.
Optimizing Large VXIbus Transfers
For best performance, keep the following in mind when using viMove()
or VXImove() :
• Make sure your buffers are 32-bit aligned.
• Transfer 32-bit data whenever possible.
• Use VXI block access privileges to significantly improve performance
to devices that are capable of accepting block transfers.
• To optimize move performance on virtual memory systems, lock the
user buffer in memory yourself so the move operation does not need to
lock the buffer.
• To optimize move performance on paged memory systems, use
a contiguous buffer so the move operation does not need to build
a scatter-gather list for the user buffer.
Table 3-1. NI-VISA/NI-VXI Examples
Coverage NI-VISA Example
NI-VXI Example
(Optional)
Message-Based
Access General\RdWrt.c VXIws.c
High-Level
Register Access VXI-VME\HighReg.c VXIhigh.c
Low-Level
Register Access VXI-VME\LowReg.c VXIlow.c
Sharing Memory VXI-VME\ShareSys.c VXImem.c
Interrupt Handling VXI-VME\AsyncIntr.c
and WaitIntr.c
VXIint.c
Trigger Handling VXI-VME\WaitTrig.c VXItrig.c