User`s guide

102 Agilent VISA User’s Guide
4 Programming via GPIB and VXI
Using High-Level Memory Functions
High- level memory functions allow you to access memory on
the interface through simple function calls. There is no need
to map memory to a window. Instead, when high- level
memory functions are used, memory mapping and direct
register access are automatically done.
The trade- off, however, is speed. High- level memory
functions are easier to use. However, since these functions
encompass mapping of memory space and direct register
access, the associated overhead slows program execution
time. If speed is required, use the low- level memory
functions discussed in “Using Low- Level Memory Functions”
on page 108.
Programming the Registers
High- level memory functions include the viIn and viOut
functions for transferring 8- , 16- , or 32- bit values, as well as
the viMoveIn and viMoveOut functions for transferring 8- ,
16- , or 32- bit blocks of data into or out of local memory.
You can therefore program using 8- , 16- , or 32- bit transfers.
High-Level Memory Functions
This table summarizes the high- level memory functions.
Table 25 Summary of High-Level Memory Functions
Function Description
viIn8(vi, space, offset, val8); Reads 8 bits of data from the specified
offset.
viIn16
(vi, space, offset, val16); Reads 16 bits of data from the specified
offset.
viIn32(vi, space, offset, val32); Reads 32 bits of data from the specified
offset.
viOut8(vi, space, offset, val8); Writes 8 bits of data to the specified offset.