User's Manual

Chapter 3 Connecting the Signals
DAQCard-1200 User Manual 3-10 ni.com
Differential Connections for Grounded Signal Sources
Figure 3-4 shows how to connect a ground-referenced signal source to a
DAQCard-1200 configured for DIFF input mode. Refer to the Configuring
Analog Input section of Chapter 2, Installing and Configuring
the DAQCard-1200, for configuration instructions.
Figure 3-4.
Differential Input Connections for Grounded Signal Sources
With this connection type, 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 3-4.
DAQCard-1200 in DIFF Configuration
Grounded
Signal
Source
Common-Mode
Noise,
Ground
Potential
V
s
V
cm
Front I/O Connector
+
–
+
–
1
3
5
7
2
4
6
8
11
ACH 0
ACH 2
ACH 4
ACH 6
ACH 1
ACH 3
ACH 5
ACH 7
AGND
+
–
+
–
Measured
Voltage
V
m