Common-Mode Signal Rejection Considerations; Figure 3-6. Single-Ended Input Connections For Grounded Signal Sources - National Instruments DAQCard-1200 User Manual

Ground-
+
Referenced
V s
Signal
Source
–
Common-Mode
+
Noise
V cm
–
Front I/O Connector
© National Instruments Corporation
ACH 0
1
ACH 1
2
ACH 2
3
ACH 7
8
9
AGND
11
DAQCard-1200 in NRSE Input Configuration

Figure 3-6. Single-Ended Input Connections for Grounded Signal Sources

Common-Mode Signal Rejection Considerations

Figures 3-3 and 3-6 show connections for signal sources that are already
referenced to some ground point with respect to the DAQCard-1200. In
these cases, the instrumentation amplifier can reject any voltage caused by
ground-potential differences between the signal source and the
DAQCard-1200. In addition, with differential input connections, the
instrumentation amplifier can reject common-mode noise pickup in the
leads connecting the signal sources to the DAQCard-1200.
The common-mode input range of the DAQCard-1200 instrumentation
amplifier is the magnitude of the greatest common-mode signal that can be
rejected.
The common-mode input range for the DAQCard-1200 depends on the size
of the differential input signal (V
instrumentation amplifier. In unipolar mode, the differential input range is
0 to 10 V. In bipolar mode, the differential input range is –5 to +5 V.
V should remain within a range of –6 to 6 V in bipolar mode and –6 to
in–
+
–
AISENSE/AIGND
= V – V
diff in+
3-13
Chapter 3 Signal Connections
+
Measured
V m
Voltage
–
) and the gain setting of the
in–
DAQCard-1200 User Manual