Using Non-Referenced Single-Ended (Nrse) Connections For Floating Signal Sources - National Instruments DAQ X Series User Manual

Chapter 4 Analog Input
Using Non-Referenced Single-Ended (NRSE)
Connections for Floating Signal Sources
It is important to connect the negative lead of a floating signals source to
AI GND (either directly or through a resistor). Otherwise the source may
float out of the valid input range of the NI-PGIA and the DAQ device
returns erroneous data.
Figure 4-8 shows a floating source connected to the DAQ device in NRSE
mode.
All of the bias resistor configurations discussed in the
Connections for Floating Signal Sources
resistors as well. Replace AI– with AI SENSE in Figures 4-4, 4-5, 4-6,
and 4-7 for configurations with zero to two bias resistors. The noise
rejection of NRSE mode is better than RSE mode because the AI SENSE
X Series User Manual
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AC Coupling
AC Coupled
+
Floating
V
Signal s
–
Source
Figure 4-7. Differential Connections for AC Coupled Floating Sources with
Balanced Bias Resistors
Floating
+
Signal
V
s
Source –
R
Figure 4-8. NRSE Connections for Floating Signal Sources
4-18
MIO X Series Device
AI+
AI–
AI SENSE
AI GND
MIO X Series Device
AI
AI SENSE
AI GND
Using Differential
section apply to the NRSE bias
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