National Instruments PCI-7813 - Page 31

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)