© National Instruments
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4-19
When to Use Referenced Single-Ended (RSE) Connections with
Ground-Referenced Signal Sources
Do
not
use RSE connections with ground-referenced signal sources. Use NRSE or DIFF
connections instead.
As shown in the bottom-rightmost cell of Table 4-3, there can be a potential difference between
AI GND and the ground of the sensor. In RSE mode, this ground loop causes measurement
errors.
Using Differential Connections for Ground-Referenced Signal
Sources
Figure 4-10 shows how to connect a ground-referenced signal source to the MIO X Series device
configured in differential mode.
Figure 4-10.
Differential Connections for Ground-Referenced Signal Sources
Note
(NI USB-6341/6343/6346/6361/6363 BNC Devices)
To measure a
ground-referenced signal source on X Series USB BNC devices, move the switch
under the BNC connector to the GS position.
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 Vcm
in the figure.
AI+ and AI- must both remain within ±11 V of AI GND.
MIO X
S
erie
s
Device Config
u
red in Differenti
a
l Mode
PGIA
–
+
–
+
–
+
–
+
V
cm
V
s
Gro
u
nd-
Referenced
S
ign
a
l
S
o
u
rce
Common-
Mode
Noi
s
e
a
nd
Gro
u
nd
Potenti
a
l
AI GND
AI
S
EN
S
E
Inp
u
t M
u
ltiplexer
s
V
m
Me
asu
red
Volt
a
ge
In
s
tr
u
ment
a
tion
Amplifier
AI+
AI–
I/O Connector
Summary of Contents for DAQ X NI 634 Series
Page 1: ...PXIe 6349...
