Chapter 5 Using the SCXI-1125
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the data corresponds to a scanned channel for easier access by
C applications. BASIC applications need not call
SCAN_Demux
to
rearrange two-dimensional arrays since these arrays are accessed in
column-major order. For more information regarding each acquisition
function, refer to the
Traditional NI-DAQ (Legacy) Function Reference
Help
installed by default in
Start»Programs»National Instruments»
NI-DAQ
.
Perform Scaling, Analysis, and Display
After acquiring raw voltage data from the acquisition functions, most
applications require adjustment by device calibration constants for
accuracy, scaling measured voltage, analysis, and graphical display.
The SCXI-1125 has stored software calibration constants loaded on the
module EEPROM that are used to achieve the absolute accuracy
specifications.
SCXI_Scale
scales an array of binary data acquired from
an SCXI channel to voltage using the stored software calibration constants
when it scales the data. You must call
SCAN_Demux
before
SCXI_Scale
if
you have multiple channels in the scan. For more information regarding
SCXI_Scale
, refer to the
Traditional NI-DAQ (Legacy) Function
Reference Help
installed by default in
Start»Programs»National
Instruments»NI-DAQ
.
After you have adjusted the measurement by the appropriate calibration
constants using
SCXI_Scale
, you can use a function from the NI
conversion library
convert.h
to convert a voltage or voltage buffer from
a voltage to units of temperature or strain. NI-ADEs also provide many
powerful analysis functions to perform digital filtering, harmonic analysis,
averaging, and complex mathematics on measurements.
After performing scaling and analysis on the acquired data, you can display
the measurements in several ways. You can use any built in GUI tools in
your ADE. NI ADEs provide many graphical controls and indicators such
as charts, graphs, gauges, slides, and plots that you can use to display
the data. There is also a built in function, found in
nidaqex.h
,
called
NIDAQPlotWaveform
that you can use to generate a simple plot of the
data.
Using Software for Multiplexed Scanning
Performing scanning operations in software depends on the ADE you are
using. While using LabVIEW, or Visual Basic, all scanning operations are
prepared in software by using an SCXI
channel string
as the input to the
channel parameter in the analog input VI or function. These ADEs also
