Using Non-Referenced Single-Ended (Nrse) Connections For Ground-Referenced Signal Sources - National Instruments DAQ X Series User Manual

Using Non-Referenced Single-Ended (NRSE)
Connections for Ground-Referenced Signal Sources
Figure 4-11 shows how to connect ground-reference signal sources in
NRSE mode.
AI <0..31> 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..15> and connect the signal local ground reference to AI SENSE.
You also can connect the signal to one of AI <16..31> and connect the
signal local ground reference to AI SENSE 2. 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.
© National Instruments
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
I/O Connector
Ground-
+
Referenced
V
Signal
s
–
Source
Common-
+
Mode
AI GND
V
cm
Noise
–
and Ground
Potential
MIO X Series Device Configured in NRSE Mode
Figure 4-11. Single-Ended Connections for Ground-Referenced Signal Sources
(NRSE Configuration)
4-23
Chapter 4
AI <0..15>
or AI <16..31>
Instrumentation
Amplifier
+
PGIA
Input Multiplexers
–
AI SENSE
or AI SENSE 2
X Series User Manual
Analog Input
+
Measured
V
m
Voltage
–