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 Vcm in Figure 3-3.

Differential Connections for Floating Signal Sources

Figure3-4 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

Chapter2, Insta llation and Configuration.

+
–
+
Grounded
Signal
Source
VmMeasured
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