Floating Signal Sources - National Instruments Data Acquisition Device NI USB-621x User Manual

Chapter 4 Analog Input
AI Ground-Reference
*
Setting
Differential (DIFF)
Non-Referenced
Single-Ended (NRSE)
Referenced Single-Ended
(RSE)
*
Refer to the Analog Input Ground-Reference Settings
software considerations.
†
Refer to the Connecting Ground-Referenced Signal Sources
NI USB-621x User Manual
Table 4-2. USB-6210/6211/6212 Analog Input Configuration

Floating Signal Sources

(Not Connected to
Building Ground)
Examples:
• Ungrounded thermocouples
• Signal conditioning with
isolated outputs
• Battery devices
Signal Source
+
–
Signal Source
+
–
Signal Source
+
–
Example:
• Plug-in instruments with
DAQ Device
AI+
+
AI–
–
AI GND
DAQ Device
AI
+
–
AI SENSE
AI GND
DAQ Device
AI
+
–
AI GND
section for descriptions of the RSE, NRSE, and DIFF modes and
section for more information.
4-24
Ground-Referenced
Signal Sources
non-isolated outputs
DAQ Device
Signal Source
AI+
+
AI–
–
AI GND
V cm
Signal Source DAQ Device
AI
+
–
AI SENSE
AI GND
V cm
NOT RECOMMENDED for the
USB-6210/6211/6212
Signal Source DAQ Device
AI
+
–
V
A
AI GND
V
B
Ground-loop potential (V – V ) are added
A B
to measured signal.
†
+
–
+
–
+
–
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