National Instruments NI USB-621x User Manual page 52

Chapter 5 Connecting AI Signals on the USB-6210/6211 Devices
AI
Ground-Reference
*
Setting
Differential
Single-Ended—
Non-Referenced
(NRSE)
Single-Ended—
Referenced (RSE)
*
Refer to the Analog Input Ground-Reference Settings
NRSE, and DIFF modes and software considerations.
**
Refer to the Connecting Ground-Referenced Signal Sources
NI USB-621x User Manual
Table 5-1. Analog Input Configuration
Floating Signal Sources (Not
Connected to Building Ground)
Examples:
• Ungrounded thermocouples
• Signal conditioning with
isolated outputs
• Battery devices
Signal Source DAQ Device
AI+
+
AI–
–
Signal Source DAQ Device
AI
+
–
Signal Source DAQ Device
AI
+
–
section of Chapter 4,
Ground-Referenced Signal
Example:
• Plug-in instruments with
non-isolated outputs
Signal Source
+
+
–
–
AI GND
Signal Source
+
+
–
–
AI SENSE
AI GND
+
Signal Source
–
+
AI GND
–
V
A
Ground-loop potential (V
Analog Input, for descriptions of the RSE,
section for more information.
5-2
**
Sources
DAQ Device
AI+
+
AI–
–
AI GND
V cm
DAQ Device
AI
+
–
AI SENSE
AI GND
V cm
NOT RECOMMENDED
for the
USB-6210/6211
DAQ Device
AI
+
–
V
B
AI GND
– V ) are added
A B
to measured signal.
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