User's Manual

Chapter 4 Signal Connections
 National Instruments Corporation 4-25 AT-MIO/AI E Series User Manual
Single-Ended Connections for Floating Signal
Sources (RSE Configuration)
Figure 4-8 shows how to connect a floating signal source to an
AT E Series board channel configured for RSE mode.
Figure 4-8. 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 AT E Series board in the NRSE input
configuration. The signal is then connected to the positive input of the
AT E Series 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 AT E Series 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 an AT E Series board 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<0..15>
AIGND
Instrumentation
Amplifier
I/O Connector
AISENSE
Selected Channel in RSE Configuration
PGIA
Input Multiplexers