National Instruments PCI-1200 - Manual (Page 36)

Chapter 3 Signal Connections
PCI-1200 User Manual 3-14 © National Instruments Corporation
RSE configuration, this difference in ground potentials appears as an error
in the measured voltage.
Figure 3-6 shows how to connect a grounded signal source to a PCI-1200
board configured in the NRSE configuration. Configuration instructions
are included in the
Analog I/O Configuration section in Chapter 2,
Installation and Configuration .
Figure 3-6. Single-Ended Input Connections for Grounded Signal Sources
Common-Mode Signal Rejection Considerations
Figures 3-4 and 3-6 show connections for signal sources that are already
referenced to some ground point with respect to the PCI-1200. In these
cases, the instrumentation amplifier can reject any voltage caused by
ground-potential differences between the signal source and the PCI-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 PCI-1200.
The common-mode input range of the PCI-1200 instrumentation amplifier
is the magnitude of the greatest common-mode signal that can be rejected.
ACH0
V
m
Measured
Voltage
Common-
Mode
Noise
and so on
AGND
AISENSE/AIGND
V
s
V
cm
+
+
+
+
I/O Connector PCI-1200 in NRSE Input Configuration
1
2
3
8
9
11
Ground-
Referenced
Signal
Source
ACH1
ACH2
ACH7
•
•
•
•
•
•
–
–
–
–