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Programmer’s Guide Page 25 of 64
3.6.3. U1084A Zero-Suppression mode – Readout configuration
The function AcqrsD1_readData() may be used to read the acquired data. The entire acquisition must be read,
reading partial acquisitions is not supported. There are no out-of-band segment descriptors in this mode, the segment
descriptors are embedded in the acquisition data. The AqReadParameters structure should be set up as follows:
• readMode: ReadModeSSRW
• firstSegment: must be 0
• nbrSegments: equal to the value set with AcqrsD1_configAvgConfigInt32("NbrSegments")
• firstSampleInSeg: must be 0
• nbrSamplesInSeg: equal to the value set with AcqrsD1_configAvgConfigInt32("NbrSamples")
• segmentOffset: unused, set to 0
• dataArraySize: the size in bytes of the user-allocated buffer to which the data is transferred
• segDescArraySize: must be 0
• flags: must be 0
• reserved, reserved2, reserved3: must be 0
The total size of the data available for readout may vary between acquisitions. The data buffer passed in the
dataArray parameter must be big enough to accommodate the worst case, which is:
maxDataSize = nbrSegments*(nbrSamples + segmentHeaderSize + gateHeaderSize) + padding
where:
• nbrSegments is the value set with AcqrsD1_configAvgConfigInt32("NbrSegments")
• nbrSamples is the value set with AcqrsD1_configAvgConfigInt32("NbrSamples")
• segmentHeaderSize is 32 bytes (see also U1084A Zero-Suppression mode - Data Format below)
• gateHeaderSize is 8 bytes (see also U1084A Zero-Suppression mode - Data Format below)
• padding is 32 bytes
Check the actualDataSize field of the AqDataDescriptor structure to find out how many bytes have actually
been transferred.
3.6.4. U1084A Zero-Suppression mode - Data Format
When operating in Zero-Suppress mode, the waveform readout contains digitized data and meta-data. The SAR
mode is supported so that the user can start another acquisition and simultaneously read the previously acquired data.
In multi-segment mode, all of the segments must be read at once with a single read command. Digitized data and
meta-data will be organized as follows:
Notes :
- All segments will be read sequentially from the first to the last acquired segment.
- Each segment always starts with an 8-word (256-bit) Segment Descriptor.
- The Segment Descriptor will be followed by the zero-suppressed digitized data. The zero-suppress readout contains
only portions of the waveform that are above the programmed threshold, each portion is called a 'Gate'.