Agilent Technologies FS2010 Guía de usuario descargar pdf (Pagina 110)

110 Agilent VISA User’s Guide

4 Programming via GPIB and VXI

A pointer to the address space where the memory was

mapped is returned in the address parameter. If the device

specified by vi does not have memory in the specified

address space, an error is returned. Some sample

viMapAddress function calls follow.

/* Maps to A32 address space */

viMapAddress(vi, VI_A32_SPACE, 0x000, 0x100,

VI_FALSE,

VI_NULL,&address);

/* Maps to A24 address space */

viMapAddress(vi, VI_A24_SPACE, 0x00, 0x80,

VI_FALSE,

VI_NULL,&address);

Reading and Writing to Device Registers

When you have mapped the memory space, use the VISA

low- level memory functions to access the device's registers.

First, determine which device register you need to access.

Then, you need to know the register's offset. See the

applicable instrument’s user manual for a description of the

registers and register locations. You can then use this

information and the VISA low- level functions to access the

device registers.

Sample: Using viPeek16

A code sample using viPeek16 follows.

ViSession defaultRM, vi;

ViUInt16 value;

ViAddr address;

ViUInt16 value;

viOpenDefaultRM(&&defaultRM);

viOpen(defaultRM, "VXI::24::INSTR", VI_NULL,

VI_NULL,

&vi);

viMapAddress(vi, VI_A16_SPACE, 0x00, 0x04,

1 2 ... 105 106 107 108 109 110 111 112 113 114 115 ... 159 160

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Agilent Technologies FS2010 Guía de usuario Pagina 110