National Instruments NI USB-621x - Manual (Page 52)

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