National Instruments SCB-68A User Manual

© National Instruments | 2-15
NI SCB-68A User Manual
Using Non-Referenced Single-Ended (NRSE) Connections for
Ground-Referenced Signal Sources
Figure 2-11 shows how to connect ground-reference signal sources in NRSE mode.
Figure 2-11. Single-Ended Connections for Ground-Referenced Signal Sources
(NRSE Configuration)
AI <0..x> and AI SENSE must both remain within ±11 V of AI GND.
To measure a single-ended, ground-referenced signal source, you must use the NRSE
ground-reference setting. Connect the signal to one of AI <0..x> and connect the signal local
ground reference to AI SENSE. AI SENSE is internally connected to the negative input of the
NI-PGIA. Therefore, the ground point of the signal connects to the negative input of the
NI-PGIA.
Any potential difference between the device ground and the signal ground appears as a
common-mode signal at both the positive and negative inputs of the NI-PGIA, and this
difference is rejected by the amplifier. If the input circuitry of a device were referenced to
ground, as it is in the RSE ground-reference setting, this difference in ground potentials would
appear as an error in the measured voltage.
You can configure the channels for RSE or NRSE input modes using DAQ Assistant.
DAQ Device Configured in NRSE Mode
Input Multiplexers
I/O Connector
AI GND
AI SENSE
AI <0..16>
–
+
–
+
V
cm
V
s
Ground-
Referenced
Signal
Source
Common-
Mode
Noise
and Ground
Potential
PGIA
–
+
–
+
V
m
Measured
Voltage
Instrumentation
Amplifier

National Instruments SCB-68A Specifications

General

Brand	National Instruments
Model	SCB-68A
Category	Cables and connectors
Language	English