Chapter 3 99
Programming Examples
C Programming Examples using VTL
Example Program
This example program queries a GPIB device for an identification string and prints
the results. Note that you must change the address if something other than the
EMC default value of 18 is required.
/*idn.c - program filename */
#include "visa.h"
#include <stdio.h>
void main ()
{
/*Open session to GPIB device at address 18 */
ViOpenDefaultRM(&defaultRM);
ViOpen(defaultRM, “GPIB0::18::INSTR”, VI_NULL,
VI_NULL, &vi);
/*Initialize device */
viPrintf(vi, “*RST\n”);
/*Send an *IDN? string to the device */
printf(vi, “*IDN?\n”);
/*Read results */
viScanf(vi, "%t", &buf);
/*Print results */
printf(“Instrument identification string: %s\n”, buf);
/* Close the sessions */
viClose(vi);
viClose(defaultRM);
}
Including the VISA Declarations File
For C and C++ programs, you must include the visa.h header file at the
beginning of every file that contains VTL function calls:
#include “visa.h”
This header file contains the VISA function prototypes and the definitions for all
VISA constants and error codes. The visa.h header file includes the
visatype.h header file.
