17-2000 C
2020-09-17
40(50)
ADQ8-8C Manual
17-2000 C 2020-09-17
40(50)
If the readout process is as fast as the acquisition process, the memory size does not impose any lim-
itations.
If readout is scheduled after recording, the total data set from the measurement has to be limited to
1 GBytes to fit in the acquisition memory.
7.3 Triggered streaming acquisition
The acquisition mode triggered streaming is described in
7.4 Acquisition mode multi-record
ADQ8-8C supports acquisition mode multi-record. This mode is suitable for most user-scheduled single
shot or multi-shot applications. It is also suitable for control and surveillance applications where the long
pre-trigger makes it possible to see what preceded an event.
In the multi-record mode, one or several records are recorded into the acquisition memory and read out
on request from the user. The multi-record mode is straight forward to implement and is easy to use if
the data set is smaller than the on-board memory. The memory (DRAM) of the digitizers is split into cir-
cular buffers where one buffer can hold one record. Data is then written constantly into this buffer until
the trigger event arrives. After the trigger event
Record_length
-
Pretrigger_samples
is written into the
buffer. The accumulation of the record is then completed. The circular buffer contains the pre-trigger
data and the post trigger data. The position of the trigger may be anywhere in the buffer. The API
unwraps the data buffer before presenting the record to the user. The multi-record gives the feature of a
very long pretrigger.
Readout only can start when the complete record is captured and is always initiated from the user's
application.
#
DESCRIPTION
USER COMMAND
REF
a
The channel mask selects which channels to record and which to
discard.
SetStreamConfig
MultiRecordSetChannelMask
b
The header generator apply header information to each record.
c
The acquisition memory is a DRAM on the digitizer which operate
as a FIFO.
Figure 29: Acquisition memory.
ACQUISITION MODE
RECORD SIZE
ADQ8-8C
Header
< 256 samples
> 5.9 %
Header
> 256 samples
< 5.9 %
Header
Asymptotic lower limit
3.1 %
Raw mode no headers
Any
0 %
Table 3:
Header memory requirement for triggered streaming acquisition mode.
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