National Instruments Multifunction RIO NI R Series, User Manual

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Chapter 2 Hardware Overview of the NI 78xxR
R Series Multifunction RIO User Manual 2-6 ni.com
Connecting Analog Input Signals
The AI signals for the NI 783 x R/784 x R/785 x R are AI<0.. n >+, AI<0.. n >–,
AIGND, and AISENSE. For the NI 7830R, n =4. For the NI 7831R/7833R/
784 x R/785 x R, n =8. The AI<0.. n >+ and AI<0.. n >– signals are connected to
the eight AI channels of the NI 783 x R/784 x R/785 x R. For all inp
u
t modes,
the AI<0.. n >+ signals are connected to the positive inp
u
t of the
instr
u
mentation amplifier on each channel. The signal connected to the
negative inp
u
t of the instr
u
mentation amplifier depends on how yo
u
config
u
re the inp
u
t mode of the device.
In differential inp
u
t mode, signals connected to AI<0.. n >– are ro
u
ted to the
negative inp
u
t of the instr
u
mentation amplifier for each channel. In RSE
inp
u
t mode, the negative inp
u
t of the instr
u
mentation amplifier for each
channel is internally connected to AIGND. In NRSE inp
u
t mode, the
AISENSE signal is connected internally to the negative inp
u
t of the
instr
u
mentation amplifier for each channel. In DIFF and RSE inp
u
t modes,
AISENSE is not
u
sed.
Caution Exceeding the differential and common-mode inp
u
t ranges distorts the
inp
u
t signals. Exceeding the maxim
u
m inp
u
t voltage rating can damage the
NI 783 x R/784 x R/785 x R and the comp
u
ter. NI is not liable for any damage res
u
lting from
s
u
ch signal connections. The maxim
u
m inp
u
t voltage ratings are listed in Table A-2,
NI 78xxR I/O Signal Summary .
AIGND is a common AI signal that is ro
u
ted directly to the gro
u
nd tie point
on the NI 783 x R/784 x R/785 x R. Yo
u
can
u
se this signal for a general analog
gro
u
nd tie point to the NI 783 x R/784 x R/785 x R if necessary.