National Instruments Low-Cost Multifunction I/O Board for ISA..., User Manual

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Chapter 2 Configuration and Installation
© National Instruments Corporation 2-13 Lab-PC+ User Manual
NRSE Input (Eight Channels)
NRSE input means that all input signals are referenced to the same common mode voltage,
which is allowed to float with respect to the analog ground of the Lab-PC+ board. This common
mode voltage is subsequently subtracted out by the input instrumentation amplifier. This
configuration is useful when measuring ground-referenced signal sources. To select the NRSE
input configuration, clear the SE
__/D bit as described in the Command Register 4 bit description in
Appendix D, Register Map and Descriptions. You must also set the following jumper.
W4: B-C Jumper is in standby position, and negative input of instrumentation amplifier
is tied to multiplexed output.
This configuration is shown in Figure 2-11.
W4
•
A
B
C
RSE
NRSE/DIFF
Figure 2-11. NRSE Input Configuration
Considerations in using the NRSE configuration are discussed in Chapter 3, Signal Connections.
Note that in this mode, the return path of the signal is through the negative terminal of the
amplifier, available at the connector through the pin AISENSE/AIGND.
Analog Input Polarity Configuration
Two ranges are available for the analog inputs–bipolar
±
5 V and unipolar 0 to 10 V. Jumper W3
controls the input range for all eight analog input channels.
Bipolar Input Selection
You can select the bipolar (
±
5 V) input configuration by setting the following jumper:
Analog Input W3 A-B
This configuration is shown in Figure 2-12.