Chapter 4
Analog Input
X Series User Manual
4-18
ni.com
Figure 4-7.
Differential Connections for AC Coupled Floating Sources with
Balanced Bias Resistors
Using Non-Referenced Single-Ended (NRSE)
Connections for Floating Signal Sources
It is important to connect the negative lead of a floating signals so
u
rce to
AI GND (either directly or thro
u
gh a resistor). Otherwise the so
u
rce may
float o
u
t of the valid inp
u
t range of the NI-PGIA and the DAQ device
ret
u
rns erroneo
u
s data.
Fig
u
re 4-8 shows a floating so
u
rce connected to the DAQ device in NRSE
mode.
Figure 4-8.
NRSE Connections for Floating Signal Sources
All of the bias resistor config
u
rations disc
u
ssed in the
Using Differential
Connections for Floating Signal Sources
section apply to the NRSE bias
resistors as well. Replace AI– with AI SENSE in Fig
u
res 4-4, 4-5, 4-6,
and 4-7 for config
u
rations with zero to two bias resistors. The noise
rejection of NRSE mode is better than RSE mode beca
u
se the AI SENSE
–
+
AI GND
V
s
AC Co
u
pled
Flo
a
ting
S
ign
a
l
S
o
u
rce
AI+
AI–
AI
S
EN
S
E
AC Co
u
pling
MIO X
S
erie
s
Device
–
+
AI GND
R
AI
S
EN
S
E
AI
V
s
Flo
a
ting
S
ign
a
l
S
o
u
rce
MIO X
S
erie
s
Device
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