National Instruments DAQ X Series User Manual

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 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.
Figure 4-8. NRSE Connections for Floating Signal Sources
All of the bias resistor configurations discussed in the Using Differential
Connections for Floating Signal Sources section apply to the NRSE bias
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
–
+
AI GND
V
s
AC Coupled
Floating
Signal
Source
AI+
AI–
AI SENSE
AC Coupling
MIO X Series Device
–
+
AI GND
R
AI SENSE
AI
V
s
Floating
Signal
Source
MIO X Series Device
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National Instruments DAQ X Series Specifications

General

Series	X Series
Resolution	16-bit
Output Voltage Range	±10 V
Analog Output Channels	Up to 4
Communication Interface	PCIe, USB
Operating Temperature Range	0°C to 50°C
Input Voltage Range	±10 V