Agilent Technologies Infiniium 8000A, Programmer'S Reference Manual

Page: 102 / 934

6- 8
Sample Programs
Sample C Programs
init.c - Making Automatic Measurements
/*
* Function name: auto_measurements
* Parameters: none
* Return value: none
* Description: This routine performs automatic measurements of volts
* peak-to-peak and frequency on the acquired data. It also demonstrates
* two methods of error detection when using automatic measurements.
*/
void auto_measurements( void )
{
float frequency, vpp;
unsigned char vpp_str[16];
unsigned char freq_str[16];
int bytes_read;
/*
* Error checking on automatic measurements can be done using one of two methods.
* The first method requires that you turn on results in the Measurements
* subsystem using the command :MEASure:SEND ON. When this is on, the oscilloscope
* will return the measurement and a result indicator. The result flag is zero
* if the measurement was successfully completed, otherwise a non-zero value is
* returned which indicates why the measurement failed.
*
* The second method simply requires that you check the return value of the
* measurement. Any measurement not made successfully will return with the value
* +9.999E37. This could indicate that either the measurement was unable to be
* performed, or that insufficient waveform data was available to make the
* measurement.
*/
/*
* METHOD ONE - turn on results to indicate whether the measurement completed
* successfully. Note that this requires transmission of extra data from the
* oscilloscope.
*/
write_IO(":MEASure:SENDvalid ON"); /* turn results on */
/* query volts peak-to-peak channel 1 */
write_IO(":MEASure:VPP? CHANnel1");
bytes_read = read_IO(vpp_str,16L); /* read in value and result flag */
if (vpp_str[bytes_read-2] != '0')
printf("Automated vpp measurement error with result %c\n",
vpp_str[bytes_read-2]);
else
printf("VPP is %f\n",(float)atof(vpp_str));