Chapter 2
Hardware Overview of the NI 78xxR
©
National Instruments Corporation
2-15
R Series Multifunction RIO User Manual
Single-Ended Connections for Grounded Signal
Sources (NRSE Input Mode)
To meas
u
re a gro
u
nded signal so
u
rce with a single-ended inp
u
t mode, yo
u
m
u
st config
u
re the NI 783
x
R/784
x
R/785
x
R in the NRSE inp
u
t mode. Then
connect the signal to the positive inp
u
t of the NI 783
x
R/784
x
R/785
x
R
instr
u
mentation amplifier and connect the signal local gro
u
nd reference to
the negative inp
u
t of the instr
u
mentation amplifier. The gro
u
nd point of the
signal sho
u
ld be connected to AISENSE. Any potential difference between
the NI 783
x
R/784
x
R/785
x
R gro
u
nd and the signal gro
u
nd appears as a
common-mode signal at both the positive and negative inp
u
ts of the
instr
u
mentation amplifier. The instr
u
mentation amplifier rejects this
difference. If the inp
u
t circ
u
itry of a NI 783
x
R/784
x
R/785
x
R is referenced
to gro
u
nd in RSE inp
u
t mode, this difference in gro
u
nd potentials appears
as an error in the meas
u
red voltage.
Fig
u
re 2-9 shows how to connect a gro
u
nded signal so
u
rce to a channel on
the NI 783
x
R/784
x
R/785
x
R config
u
red for NRSE inp
u
t mode.
Figure 2-9.
Single-Ended Input Connections for Ground-Referenced Signals
–
+
–
+
–
+
–
+
V
cm
V
s
I/O Connector
AISENSE
AIGND
V
m
AI+
AI–
Instrumentation
Amplifier
Measured
Voltage
Ground-
Referenced
Signal
Source
Common-
Mode
Noise and
Ground
Potential
NRSE Input Mode Selected
Summary of Contents for Multifunction RIO NI R Series
Page 1: ...PXI 7813...
