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Ground-
+
Referenced
Signal
V
s
Source
–
Common-
+
Mode
Noise and
V
cm
Ground
–
Potential
I/O Connector
© National Instruments Corporation
Differential Connections for Ground-Referenced
Signal Sources
Figure 2-6 shows how to connect a ground-referenced signal source to a
channel on the NI 783xR/784xR/785xR configured in DIFF input mode.
AI+
AI–
AISENSE
AIGND
DIFF Input Mode Selected
Figure 2-6. Differential Input Connections for Ground-Referenced Signals
With this connection type, the instrumentation amplifier rejects both the
common-mode noise in the signal and the ground potential difference
between the signal source and the NI 783xR/784xR/785xR ground, shown
as V
in Figure 2-6. In addition, the instrumentation amplifier can reject
cm
common-mode noise pickup in the leads connecting the signal sources to
the device. The instrumentation amplifier can reject common-mode signals
when V+
and V–
(input signals) are both within their specified input
in
in
ranges. Refer to the NI R Series Intelligent DAQ Specifications, available at
, for more information about input ranges.
ni.com/manuals
Chapter 2
+
Instrumentation
Amplifier
–
2-11
Hardware Overview of the NI 78xxR
+
Measured
V
m
Voltage
–
R Series Intelligent DAQ User Manual
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