National Instruments AT-MIO-64F-5, User Manual

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Configuration and Installation Chapter 2
AT-MIO-64F-5 User Manual 2-22 © National Instruments Corporation
Differential Connections for Ground-Referenced Signal Sources
Figure 2-7 shows how to connect a ground-referenced signal source to an AT-MIO-64F-5 board
configured in the DIFF input mode. The AT-MIO-64F-5 analog input circuitry must be
configured for DIFF input to make these types of connections. Configuration instructions are
included in Chapter 4,
Register Map and Descriptions.
AT-MIO-64F-5 Board in the DIFF Input Configuration
Ground-
Referenced
Signal
Source
Common-
Mode
Noise,
Ground
Potential,
and so on
Input Multiplexers
AI SENSE
PGIA
V
m
Measured
Voltage
AI GND
-
+
-
+
V
s
V
cm
+
-
-
+
I/O Connector
ACH<0..7>
ACH<8..15>
Gain
ACH<40..63>
ACH<16..39>
Figure 2-7. Differential Input Connections for Ground-Referenced Signals
With this type of connection, the PGIA rejects both the common-mode noise in the signal and
the ground potential difference between the signal source and the AT-MIO-64F-5 ground, shown
as V
cm
in Figure 2-7.