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2-14
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Chapter 2
Analog Input and Temperature Sensor Measurements
Using Differential Connections for Ground-Referenced Signal
Sources
Figure 2-10 shows how to connect a ground-referenced signal source to the DAQ device
configured in differential mode.
Figure 2-10.
Differential Connections for Ground-Referenced Signal Sources
With this type of connection, the NI-PGIA 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
cm
in the figure.
AI+ and AI– must both remain within ±11 V of AI GND.
DAQ Device Config
u
red in Differenti
a
l Mode
PGIA
–
+
–
+
–
+
–
+
V
cm
V
s
Gro
u
nd-
Referenced
S
ign
a
l
S
o
u
rce
Common-
Mode
Noi
s
e
a
nd
Gro
u
nd
Potenti
a
l
AI GND
AI
S
EN
S
E
Inp
u
t M
u
ltiplexer
s
V
m
Me
asu
red
Volt
a
ge
In
s
tr
u
ment
a
tion
Amplifier
AI
+
AI
–
I/O Connector