134 Chapter 3
Programming Examples
Reading Trace Data Using 32-bit Real Format (RS-232)
/*Calculate size of trace record. This will be the sum of HeaderBytes, Number*/
/*Bytes (the actual data bytes) and the "\n" terminator*/
iSize = lNumberBytes + iHeaderBytes + 1;
/*Increase timeout to 60 sec*/
viSetAttribute(viESA,VI_ATTR_TMO_VALUE,60000);
/*Set RS-232 interface to terminate when the buffer is empty*/
viSetAttribute(viESA,VI_ATTR_ASRL_END_IN,VI_ASRL_END_NONE);
/*Get trace header data and trace data*/
viPrintf(viESA,"TRAC:DATA? TRACE1\n");
viRead (viESA,(ViBuf)cResult,iSize,&lRetCount);
/*Reset timeout to 3 sec*/
viSetAttribute(viESA,VI_ATTR_TMO_VALUE,3000);
/*Extract the trace data*/
memcpy(dTraceArray,cResult+iHeaderBytes,(size_t)lNumberBytes);
/*Save trace data to an ASCII file*/
fTraceFile=fopen("C:\\temp\\ReadTrace32Rs232.txt","w");
fprintf(fTraceFile,"ReadTrace32Rs232.exe Output\nHewlett-Packard 1999\n\n");
fprintf(fTraceFile,"The %d trace data points of the
spectrum:\n\n",(lNumberBytes/4));
for ( long i=0;i<lNumberBytes/iBytesPerPnt;i++)
fprintf(fTraceFile,"\tAmplitude of point[%d] = %.2lf
dBm\n",i+1,dTraceArray[i]);
fclose(fTraceFile);
/*Close the session*/
viClose(viESA);
viClose(defaultRM);
}
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