Teledyne SP Devices ADQ7DC, Manual

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7 ACQUISITION CONTROL
The acquisition control consists of two partly independent parts;
•
acquisition of data in a record
• transfer to host PC.
Figure 28 shows the flow of data through acquisition and data transfer.
7.1 Multi-thread notice
Note that the digitizer does not support multi-threaded applications. In the triggered streaming mode,
however, a multi-threading programming style has advantages. In such an application, make sure that
only one thread communicates with the digitizer at a time.
In the example in
Section 7.4.1 , one thread handles the control of the digitizer. The other thread only
processes data.
Example code available with the digitizer is sometimes written with several threads. Study these exam-
ples carefully to see how multi-threading can be used.
7.2 Acquisition memory
The acquisition memory, Figure 29 , is of size 4 GBytes.
The memory is shared by all activated channels which means that if only one channel is activated, the
entire memory is available for that channel.
The data memory is also shared between data and headers,
Table 5 . A header contains information
about the data record, for example, timestamp and channel number. The headers can be setup in two
different modes:
•
In the normal mode, the headers are activated. This mode is recommended for all standard acqui-
sition modes.
• In the raw mode, there are no headers and all available memory is used for data. The raw mode is
only recommended for custom firmware built in the ADQ Development Kit.
# DESCRIPTION REF
a The A/D converter digitizes the analog signal and generate a flow of data.
b The acquisition engine manages the data acquisition and builds records of the data. Select
acquisition mode:
Continuous streaming
Triggered streaming
Multi-record 7.3
c The transfer of data to the host PC delivers data in buffers for the user. Select mode of data
transfer:
Streaming (Real-time driven)
Scheduled (Multi-record) 7.4
d User’s application reads data and headers for further processing and/or storage. 7.1 , 7.5 ,
Figure 28: Acquisition control and data transfer.
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