National Instruments E Series - Manual (Page 51)

Chapter 4 Signal Connections
 National Instruments Corporation 4-15 DAQCard E Series User Manual
Differential Connections for Ground-Referenced
Signal Sources
Figure 4-4 shows how to connect a ground-referenced signal source to
a channel on a DAQCard configured in DIFF input mode.
With this type of connection, the PGIA rejects both the common-mode
noise in the signal and the ground potential difference between the
signal source and the DAQCard ground, shown as V
cm
in Figure 4-4.
Figure 4-4. Differential Input Connections for Ground-Referenced Signals
Ground-
Referenced
Signal
Source
Common-
Mode
Noise and
Ground
Potential
Input Multiplexers
AISENSE
Instrumentation
Amplifier
V
m
Measured
Voltage
AIGND
-
+
-
+
V
s
V
cm
+
-
-
+
I/O Connector
ACH<0..7>
ACH<8..15>
Selected Channel in DIFF Configuration
PGIA