Differential Connections For Ground-Referenced Signal Sources - National Instruments DAQ X Series User Manual

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