Technical data

144 Chapter 9
Programming Examples
Programming in C Using the VISA
Programming Examples
Example Program
This example program queries a LAN device for an identification string
and prints the results. Note that you must change the address.
/*idn.c - program filename */
#include "visa.h"
#include <stdio.h>
void main ()
{
/*Open session to LAN device at IP address 192.168.0.2
*/
ViOpenDefaultRM (&defaultRM);
ViOpen (defaultRM, "TCPIP0::192.168.0.2::inst0::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 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 VISA 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.
The visatype.h header file defines most of the VISA types. The VISA
types are used throughout VISA to specify data types used in the
functions. For example, the viOpenDefaultRM function requires a
pointer to a parameter of type ViSession. If you find ViSession in the
visatype.h header file, you will find that ViSession is eventually
typed as an unsigned long.