National Instruments DAQ X Series User Manual page 62

Chapter 4 Analog Input
You can fully balance the signal path by connecting another resistor of
the same value between the positive input and AI GND, as shown in
Figure 4-6. This fully balanced configuration offers slightly better noise
rejection, but has the disadvantage of loading the source down with the
series combination (sum) of the two resistors. If, for example, the source
impedance is 2 kΩ and each of the two resistors is 100 kΩ, the resistors
load down the source with 200 kΩ and produce a –1% gain error.
X Series User Manual
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Floating
+
Signal
V
s
Source
–
R is about
R
100 times
source
impedance
of sensor
Figure 4-5. Differential Connections for Floating Signal Sources with
Single Bias Resistor
4-16
MIO X Series Device
AI+
AI–
AI SENSE
AI GND
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