National Instruments DAQCard-1200 - Manual (Page 31)

Chapter 3 Signal Connections
© National Instruments Corporation 3-9 DAQCard-1200 User Manual
Figure 3-3. Differential Input Connections for Grounded Signal Sources
With this type of connection, the instrumentation amplifier rejects both the
common-mode noise in the signal and the ground-potential difference
between the signal source and the DAQCard-1200 ground, which is shown
as V
cm
in Figure 3-3.
Differential Connections for Floating Signal Sources
Figure 3-4 shows how to connect a floating signal source to a
DAQCard-1200 that is configured for DIFF input. Configuration
instructions are included in the
Analog Input Configuration section of
Chapter 2, Installation and Configuration .
+
–
+
Grounded
Signal
Source
Vm
Measured
Voltage
–
Vs
–
+
Front I/O Connector
DAQCard-1200 in DIFF Configuration
1
3
5
7
2
4
6
8
ACH 0
AGND 11
ACH 2
ACH 4
ACH 6
ACH 1
ACH 3
ACH 5
ACH 7
Vcm
–
+
Common-Mode
Noise,
Ground
Potential