Agilent Technologies E4438C - Queries Using VISA and C

Programming Examples
GPIB Programming Examples
Chapter 2 45
Queries Using VISA and C
This example uses VISA library functions to query different instrument states and conditions.
Launch Microsoft Visual C++ 6.0, add the required files, and enter the following code into
your .cpp source file.
The following program example is available on the ESG Documentation CD-ROM as
visaex3.cpp.
//****************************************************************************************
// PROGRAM FILE NAME:visaex3.cpp
//
// PROGRAM DESCRIPTION:This example demonstrates the use of query commands. The signal
// generator can be queried for conditions and instrument states. These commands are of
// the type "*IDN?"; the question mark indicates a query.
//
//****************************************************************************************
#include <visa.h>
#include "StdAfx.h"
#include <iostream>
#include <conio.h>
#include <stdlib.h>
using namespace std;
void main ()
{
ViSession defaultRM, vi; // Declares variables of type ViSession
// for instrument communication
ViStatus viStatus = 0; // Declares a variable of type ViStatus
// for GPIB verifications
char rdBuffer [256]; // Declares variable to hold string data
int num; // Declares variable to hold integer data
// Initialize the VISA system
viStatus=viOpenDefaultRM(&defaultRM);
// Open session to GPIB device at address 19
viStatus=viOpen(defaultRM, "GPIB::19::INSTR", VI_NULL, VI_NULL, &vi);
if(viStatus){ // If problems, then prompt user
printf("Could not open ViSession!\n");
printf("Check instruments and connections\n");
printf("\n");
exit(0);}
viPrintf(vi, "*RST\n"); // Resets signal generator
viPrintf(vi, "FREQ:CW?\n"); // Querys the CW frequency
viScanf(vi, "%t", rdBuffer); // Reads response into rdBuffer
// Prints the source frequency
printf("Source CW frequency is : %s\n", rdBuffer);
printf("Press any key to continue\n");
printf("\n"); // Prints new line character to the display