Chapter 4
Analog Input
X Series User Manual
4-48
ni.com
Differential Connections for Ground-Referenced
Signal Sources
Fig
u
re 4-26 shows how to connect a gro
u
nd-referenced signal so
u
rce to a
channel on an Sim
u
ltaneo
u
s MIO X Series device.
Figure 4-26.
Differential Connection for Ground-Referenced Signals on Simultaneous
MIO X Series Devices
With these types of connections, the instr
u
mentation amplifier rejects both
the common-mode noise in the signal and the gro
u
nd potential difference
between the signal so
u
rce and the device gro
u
nd, shown as V
cm
in
Fig
u
re 4-26.
Common-Mode Signal Rejection Considerations
The instr
u
mentation amplifier can reject any voltage ca
u
sed by gro
u
nd
potential differences between the signal so
u
rce and the device. In addition,
the instr
u
mentation amplifier can reject common-mode noise pick
u
p in the
leads connecting the signal so
u
rces to the device. The instr
u
mentation
amplifier can reject common-mode signals as long as V+
in
and V–
in
(inp
u
t
signals) are both within the working voltage range of the device.
Ground-
Referenced
Signal
Source
Common-
Mode Noise
and Ground
Potential
V
s
V
cm
+
–
+
–
I/O Connector
AI 0 Connections Shown
AI 0 GND
AI 0 –
AI 0 +
+
–
+
–
V
m
Measured
Voltage
Instrumentation
Amplifier
Simultaneous X Series Device
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