National Instruments SCXI-1521, User Manual

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Chapter 3 Configuring and Testing
© National Instruments Corporation 3-3 SCXI-1521/B User Manual
NI-DAQmx
Note All software configurable settings are not configurable both ways. This section only
discusses settings in MAX. Refer to Chapter 4, Theory of Operation , for information about
using functions in your application.
Strain and custom voltage with excitation are the most commonly used
NI-DAQmx
task or NI-DAQmx Global Channel types with the
SCXI-1521/B. The following list describes the settings you can use in
MAX and where they are located:
• Voltage excitation—configure using either NI-DAQmx Task or
NI-DAQmx Global Channel . You can also set the voltage excitation
level through your application. In NI-DAQmx, you can choose from
contiguous voltages between 0 and 5 V. The default voltage excitation
in NI-DAQmx is 0 V.
• Input signal range—configure the input signal range using either
NI-DAQmx Task or NI-DAQmx Global Channel . When you set the
minimum and maximum range of NI-DAQmx Task or NI-DAQmx
Global Channel , the driver selects the best gain for the measurement.
• Calibration settings—fine null potentiometer settings and control
shunt calibration switches only using
Strain NI-DAQmx Task ,
Strain NI-DAQmx Global Channel , or your application. The
Custom Voltage with Excitation NI-DAQmx Task or NI-DAQmx
Global Channel cannot adjust calibration settings in MAX. Adjust
calibration settings in your application. The default configuration
settings set the fine null potentiometer to 2,048, which is its midrange
value. The default state of the shunt calibration switches is open. This
state leaves the shunt calibration resistor disconnected from the circuit.
• Modes of operation—refer to Chapter 1, About the SCXI-1521/B , for
more information about chassis installation. The default setting in
NI-DAQmx is multiplexed.
Creating a Strain Global Channel or Task
To create a new NI-DAQmx strain global task or channel, complete the
following steps:
1. Launch MAX.
2. Right-click Data Neighborhood , and select Create New .
3. Select NI-DAQmx Task or NI-DAQmx Global Channel , and click
Next .
4. Select Analog Input .