Chapter 2
Hardware Overview of the NI 78xxR
R Series Multifunction RIO User Manual
2-10
ni.com
Differential Connection Considerations (DIFF Input Mode)
In DIFF inp
u
t mode, the NI 783
x
R/784
x
R/785
x
R meas
u
res the difference
between the positive and negative inp
u
ts. DIFF inp
u
t mode is ideal for
meas
u
ring gro
u
nd-referenced signals from other devices. When
u
sing
DIFF inp
u
t mode, the inp
u
t signal connects to the positive inp
u
t of the
instr
u
mentation amplifier and its reference signal, or ret
u
rn, connects to the
negative inp
u
t of the instr
u
mentation amplifier.
Use differential inp
u
t connections for any channel that meets any of the
following conditions:
•
The inp
u
t signal is low level (less than 1 V).
•
The leads connecting the signal to the NI 783
x
R/784
x
R/785
x
R are
greater than 3 m (10 ft).
•
The inp
u
t signal req
u
ires a separate gro
u
nd-reference point or ret
u
rn
signal.
•
The signal leads travel thro
u
gh noisy environments.
Differential signal connections red
u
ce noise pick
u
p and increase
common-mode noise rejection. Differential signal connections also
allow inp
u
t signals to float within the common-mode limits of the
instr
u
mentation amplifier.
Summary of Contents for NI 783 R Series
Page 1: ...PXI 7854...
