Common-Mode Signal Rejection Considerations; Figure 4-7. Single-Ended Input Connections For Ground-Referenced Signals - National Instruments E Series User Manual

Chapter 4 Signal Connections
Ground-
Referenced
Signal
Source
Common-
Mode
V
Noise
and Ground
Potential
I/O Connector

Figure 4-7. Single-Ended Input Connections for Ground-Referenced Signals

Common-Mode Signal Rejection Considerations

DAQCard E Series User Manual
Figure 4-7 shows how to connect a grounded signal source to a channel
on a DAQCard configured for NRSE mode.
+
V
s
-
Input Multiplexers
+
AIGND
cm
-
Selected Channel in NRSE Configuration
Figures 4-4 and 4-7 show connections for signal sources that are
already referenced to some ground point with respect to the DAQCard.
In these cases, the PGIA can reject any voltage caused by ground
potential differences between the signal source and the DAQCard. In
addition, with differential input connections, the PGIA can reject
common-mode noise pickup in the leads connecting the signal sources
to the DAQCard. The PGIA can reject common-mode signals as long
as V + in and V - in are both within 11 V of AIGND. The
DAQCard-AI-16XE-50 has the additional restriction that (V + in + V - in )
added to the gain times (V + in - V - in ) must be within 26 V of AIGND.
At gains of 10 and 100, this is roughly equivalent to restricting the two
input voltages to within 8 V of AIGND.
ACH<0..15>
AISENSE
4-20
Instrumentation
Amplifier
+
PGIA
+
Measured
V
-
m
-
National Instruments Corporation
Voltage