Analog Input Channels; Figure 2-4. Ground-Referenced Signal Connection With High Common-Mode Voltage; Figure 2-5. Floating Signal Connection Referenced To Chassis Ground For - National Instruments SCXI-1121 User Manual

Chapter 2 Configuration and Installation
SCXI-1121 User Manual

Analog Input Channels

The positive input channels are located in column A. Their corresponding
negative input channels are located in column C. Each input corresponds to
a separate amplifier and is fully isolated from the other channels and from
earth ground. The inputs are designed in a floating single-ended
configuration, hence the measured signal can be referenced to a ground
level with common-mode voltage up to 250 V
immunity, connect the negative input channel to the signal reference. If the
measured signals are floating, connect the negative input channel to chassis
ground on the terminal block. Figure 2-4 shows how to connect a
ground-referenced signal. Figure 2-5 shows how to connect a floating
signal. Figures 2-6 and 2-7 show how to connect AC-coupled signals.
+
V
s
–
+
High
V
cm
CMV
–

Figure 2-4. Ground-Referenced Signal Connection with High Common-Mode Voltage

+
V
s
–
Figure 2-5. Floating Signal Connection Referenced to Chassis Ground for Better
+
Module
+
Signal-to-Noise Ratio
2-20
. For better noise
rms
+
V
out
–
+
V
out
–
Module
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