3.2 Simultaneous acquisition and readout (CST option)
Acqiris SA240P User's Manual 31
The “data stream” concept
A data stream is defined as a sequence of data elements
made available over time. In current implementation,
there are 4 streams:
2 data streams containing the acquired samples for each
channel
2 markers stream containing the time-stamps for each
channel
Each stream can be read independently and in a time
multiplexed manner allowing a fine tuning of the system
and application performance.
All the streams are channeled into a single "pipe" which
corresponds to the PCIe interface. The size of the “pipe”
represents the volume of data flow that can be extracted
from the card. When the stream data rate is larger than
the available PCIe data bandwidth, an overflow occurs
and the acquisition stops.
Figure 3.4 - Illustration of the data stream concept.
Usage
Acquisition
User should define:
the record size: the number of samples per record should be a multiple of 32,
the number of elements to fetch: should be a multiple of 16,
then, simply starts the acquisition.
The maximum amount of data that can be streamed in a single CST acquisition is:
2
48
– 64 bytes.
The maximum record size is 2'013'265'856 samples (with the lagest memory option).
Output data format
Output data streaming is managed by the application. Raw data and markers are provided without
any processing.
Each streams can be read independently or ignored.
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