Using Differential Connections For Ground-Referenced Signal Sources - National Instruments NI 6221 User Manual

Using Differential Connections for Ground-Referenced Signal Sources

Ground-
Referenced
Signal
Source
Common-
Mode
Noise and
Ground
Potential
© National Instruments Corporation
Figure 4-10 shows how to connect a ground-referenced signal source to the
M Series device configured in DIFF mode.
+
V
s
–
+
V
cm
–
Input Multiplexers
AI SENSE
AI GND
I/O Connector
M Series Device Configured in DIFF Mode
Figure 4-10. Differential Connections for Ground-Referenced Signal Sources
With this type of connection, the NI-PGIA rejects both the common-mode
noise in the signal and the ground potential difference between the signal
source and the device ground, shown as V
AI+ and AI– must both remain within ±11 V of AI GND.
AI +
Instrumentation
+
PGIA
AI –
–
4-23
Chapter 4
Amplifier
+
Measured
V
m
Voltage
–
in the figure.
cm
M Series User Manual
Analog Input