VTI Instruments EX1629, Руководство пользователя

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VTI Instruments Corp.
210 EX1629 Command Set
vtex1629_read_fifoEx
F
UNCTION
P
ROTOTYPE
ViStatus vtex1629_read_fifoEx (ViSession vi , ViInt32 maxscans , ViReal64 _VI_FAR seconds[] ,ViReal64
_VI_FAR nanoSeconds[] ,ViPInt32 numscans , ViInt32 maxdata , ViReal64 _VI_FAR data[] , ViPInt32 numdata ,
ViInt32 maxConfData , ViReal64 _VI_FAR confData[] , ViPInt32 numConfData , ViInt32 to_secs );
F
UNCTION
P
ARAMETERS
vi = contains a session handle to the instrument. This handle is obtained by the function and remains valid until the
session is closed.
maxscans = an integer input value indicating the maximum number of scans that the function should return from the
EX1629.
seconds = a returned array of real numbers. Each element in the array contains a time stamp, in seconds (s),
corresponding to a single scan taken by the instrument.
nanoSeconds = a returned array of real numbers. Each element in the array contains a time stamp, in nanoseconds
(ns), corresponding to a single scan taken by the instrument.
numscans = a returned integer value indicating the number of scans actually returned by the function call.
maxdata = an integer input value indicating the maximum length of the data array.
data = a returned array of real numbers containing data sampled from the main inputs.
numdata = an integer return value indicating the number of data elements actually returned in the data array.
maxConfData = an integer input value indicating the maximum length of the confData array.
confData = a returned array of real numbers containing sampled confidence data. See Description below for more
information.
numConfdata = an integer return value indicating the number of elements actually returned in the confData array.
to_secs = an integer input value indicating the time, in seconds, that the function will spend retrieving data from the
EX1629 before timing out and returning. If a zero is passed for this parameter, the timeout period is infinite.
D
ATA
I
TEM
R
ESET
V
ALUE
Not applicable to this function.
D
ESCRIPTION
This function retrieves data from the instrument. Once data is retrieved, the data is permanently erased from the
EX1629. In contrast to vtex1629_read_fifo, vtex1629_read_fifoEx provides access to additional acquisition data.
Even more data is available via the streaming data interface (please see
Retrieving Data (Read FIFO and Streaming
Data) for more information).
The following data is returned from this function:
• Data timestamps in seconds (s) and nanoseconds (ns)
• Number of scans returned
• Sampled data from the main inputs • Number of data points returned
• Confidence data • Number of confidence data elements returned
Data items from the
data parameter are organized in the array according to the scan list set at the time of data
acquisition. For example, if channels 0 through 15 are the scan list channels at the time of acquisition, then after a
vtex1629_read_fifo function call is made, the first sixteen elements of the
data array will correspond to the data
from the first scan for channels 0 through 15(if there is a second scan of data, the next sixteen elements would
contain the second scan, etc.).
For each scan of data returned, there will be one timestamp (a seconds and a nanoseconds value) and a number of
data values equal to the length of the scanlist. Assuming that the timestamp and data arrays are sized properly, the
number of data elements returned (numdata) will be equal to numscans multiplied by the scanlist length.
The
confData parameter is very similar to the data parameter. Where the data parameter returns a one-to-one
channel-to-data ratio based on the scan list configuration, the confData has an additional scan list of its own
(configured via vtex1629_set_conf_scanlist) that indicates how much confidence data will be acquired. If the