Chapter 4
Signal Connections
4-16
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Single-Ended Connections for Floating Signal
Sources (RSE Configuration)
Figure 4-6 shows how to connect a floating signal source to a channel
configured for RSE mode.
Figure 4-6.
Single-Ended Input Connections for Nonreferenced or Floating Signals
Single-Ended Connections for Grounded Signal
Sources (NRSE Configuration)
To measure a grounded signal source with a single-ended configuration,
you must configure your device in the NRSE input configuration. The
signal is then connected to the positive input of the PGIA, and the signal
local ground reference is connected to the negative input of the PGIA. The
ground point of the signal should, therefore, be connected to the AISENSE
pin. Any potential difference between the device ground and the signal
ground appears as a common-mode signal at both the positive and negative
inputs of the PGIA, and this difference is rejected by the amplifier. If the
input circuitry of a device were referenced to ground, in this situation as in
the RSE input configuration, this difference in ground potentials would
appear as an error in the measured voltage.
V
s
+
+
+
–
–
–
V
m
Measured
Voltage
Floating
Signal
Source
ACH
AIGND
I/O Connector
AISENSE
Selected Channel in RSE Configuration
PGIA
Input Multiplexers
Programmable Gain
Instrumentation Amplifier
