National Instruments PCI-6023E - Manual (Page 47)

Chapter 4 Signal Connections
PCI-6023E/6024E/6025E User Manual 4-18 © National Instruments Corporation
Single-Ended Connections for Floating Signal
Sources (RSE Configuration)
Figure 4-7 shows how to connect a floating signal source to a channel
configured for RSE mode.
Figure 4-7. 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 board in the NRSE input configuration. The signal
is then connected to the positive input of the PCI 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 board 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 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
AIGND
I/O Connector
AISENSE
Selected Channel in RSE Configuration
PGIA
Input Multiplexers
Programmable Gain
Instrumentation Amplifier
PCI.book Page 18 Wednesday, September 16, 1998 9:09 AM