Agilent Technologies FS2010 Guide de l'utilisateur télécharger pdf (Page 54)

54 Agilent VISA User’s Guide

3 Programming with VISA

/* Initialize device */

viPrintf(vi, "*RST\n");

/* Set up device and send a comma-separated

list */

viPrintf(vi, "CALC:DBM:REF 50\n");

viPrintf(vi, "MEAS:VOLT:AC? %,2f\n", list);

/* Read results */

viScanf(vi, "%lf", &res);

/* Print results */

printf("Measurement Results: %lf\n", res);

/* Close session */

viClose(vi);

viClose(defaultRM);

}

Using Non-Formatted I/O

There are two non- buffered, non- formatted I/O functions

that synchronously transfer data called viRead and viWrite.

Also, there are two non- formatted I/O functions that

asynchronously transfer data called viReadAsync and

viWriteAsync. These are raw I/O functions and do not

intermix with the formatted I/O functions.

Non-Formatted I/O Functions

The non- formatted I/O functions follow. For more

information, see the viRead, viWrite, viReadAsync,

viWriteAsync, and viTerminate functions in the VISA Online

Help.

viRead. The viRead function synchronously reads raw

data from the session specified by the vi parameter and

stores the results in the location where buf is pointing.

Only one synchronous read operation can occur at any

one time.

viRead(vi, buf, count, retCount);

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Agilent Technologies FS2010 Guide de l'utilisateur Page 54