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Programmer’s Guide Page 42 of 66

3.11.5.2. Averaged Waveforms as 32-bit Sums

You must use the general-purpose function AcqrsD1_readData.

Use this code fragment:

AqReadParameters readParams;// Read Definitions

AqDataDescriptor wfDesc; // Returned (common) waveform values

AqSegmentDescriptorAvg segDesc; // Returned segment values

long channel = 1, nbrSamples = 20000;

long waveformArray[20000];

readParams.dataType = ReadInt32; // Request 32-bit sums

readParams.readMode = ReadModeAvgW;

readParams.nbrSegments = 1;

readParams.firstSampleInSeg = 0;

readParams.segmentOffset = nbrSamples;

readParams.firstSegment = 0; // Read first segment

readParams.nbrSamplesInSeg = nbrSamples;

readParams.dataArraySize = sizeof(waveformArray);

readParams.segDescArraySize = sizeof(segDesc);

readParams.flags = 0;

readParams.reserved = 0;

readParams.reserved2 = 0.0;

readParams.reserved3 = 0.0;

AcqrsD1_readData(instrID, channel, &readParams, waveformArray, &wfDesc,

&segDesc);

The returned data values in waveformArray are unipolar, i.e. the raw ADC values are coded as values between 0 and

255, so that the summed data values may run between 0 and 255*N (N= number of waveforms in the sum).

3.11.6. Reading a RT Add/Subtract Averaged Waveform from an Averager

This case is significantly different than the normal averager case described above.

The „raw‟ sums now have to be considered as signed values. The relationship between Volts and the raw sum is

expressed by the following formula:

sum[i] = volts[i] * 256 * nbrWforms / FS

with the same definitions as before. However, the user has to understand if the final result corresponds to the desired

signal or just half of it.

3.11.7. Reading SSR Analyzer Waveforms

3.11.7.1. SSR Mode Readout Data Format

In all cases data values are returned in the range [–128, +127]. The relationship between Volts and the raw data is

expressed by the following formula:

data[i] = (volts[i] + offset) * 256 / FS

with the following definitions:

data[i]

8-bit signed ADC value at position i

volts[i]

floating point voltage at position i, as returned by the code fragments above

offset

offset in Volts, as set with AcqrsD1_configVertical

full scale range in Volts, as set with AcqrsD1_configVertical

In all cases you must readout the entire acquisition. You cannot ask for a reduced number of segments.