Introduction
13
outputs of instruments and devices that plug into the existing power
systems are ground-referenced signal sources.
Input Configurations
Differential Input Mode
Differential input mode provides positive signal and negative signal
inputs that respond to signal voltage difference between them, as
shown. If the signal source is ground-referenced, differential mode
can be used for noise rejection for improvement over single-ended
mode.
Figure 1-10: GRND-Referenced Source w/ DIFF Input
Connection of a floating signal source to the USB-61210 module in
differential input mode is further shown. For floating signal sources,
the negative side of the signal should be connected to the AIGND,
with less noise coupled into the signal connections than in single-end
mode.
Figure 1-11: Floating Source w/ DIFF Input
AIxH
AIxL
x = 0, ..., 3
Ground
referenced
signal source
To A/D
converter
IGND
+
-
Instrumentation amplifier
V
cm
Common-mode
noise & Ground
potential
+
-
Input multiplexer
AIxH
AIxL
x = 0, ..., 3
+
To A/D
Converter
IGND
+
-
-
Instrumentation
Amplifier
Input Multiplexer
Floating
Signal
Source
Summary of Contents for USB-61210
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