National Instruments NI 784xR, User Manual

Page: 30 / 74

Chapter 2 Hardware Overview of the NI 78xxR
© National Instruments Corporation 2-9 R Series Intelligent DAQ User Manual
Figure 2-5 summarizes the recommended input mode for both types of
signal sources.
Figure 2-5. Summary of Analog Input Connections
+
–
+
–
V
1
AI< i >
AISENSE
AIGND< i >
+
–
+
–
V
1
AI< i >
AISENSE
AIGND< i >
See text for information on bias resistors.
+
–
+
–
V
1
AI< i >
AIGND< i >
+
–
+
–
V
1
AI
+ V
g
–
AIGND
Ground-loop losses, V
g
, are added to
measured signal.
NOT RECOMMENDED
+
–
+
–
V
1
AI< i >(+)
AI< i >(–)
AIGND< i >
+
–
+
–
V
1
AI< i >(+)
AI< i >(–)
AIGND< i >
See text for information on bias resistors.
Signal Source Type
Floating Signal Source
(Not Connected to Building Ground)
Grounded Signal Source
Examples
• Ungrounded Thermocouples
• Signal Conditioning with
Isolated
Outputs
• Battery Devices
Examples
• Plug-in Instruments with
Nonisolated
Outputs
Input
Differential
(DIFF)
Single-Ended—
Ground
Referenced
(RSE)
Single-Ended—
Nonreferenced
(NRSE)