Chapter 2
Hardware Overview of the NI 78xxR
©
National Instruments Corporation
2-5
R Series Intelligent DAQ User Manual
Input Modes
The NI 783
x
R/784
x
R/785
x
R input mode is software configurable. The
input channels support three input modes—differential (DIFF), referenced
single ended (RSE), and nonreferenced single ended (NRSE). The selected
input mode applies to all the input channels. Table 2-2 describes the three
input modes.
Input Range
The NI 783
x
R/784
x
R/785
x
R AI range is fixed at ±10 V.
Negative full-scale range +1 LSB
–9.999695
8001
Negative full-scale range
–10.000000
8000
Any input voltage
—
Table 2-2.
Available Input Modes for the NI 783
x
R/784
x
R/785
x
R
Input Mode
Description
DIFF
When the NI 783
x
R/784
x
R/785
x
R is configured in DIFF input mode, each
channel uses two AI lines. The positive input pin connects to the positive terminal
of the onboard instrumentation amplifier. The negative input pin connects to the
negative input of the instrumentation amplifier.
RSE
When the NI 783
x
R/784
x
R/785
x
R is configured in RSE input mode, each
channel uses only its positive AI pin. This pin connects to the positive terminal
of the onboard instrumentation amplifier. The negative input of the
instrumentation amplifier connects internally to the AI ground (AIGND).
NRSE
When the NI 783
x
R/784
x
R/785
x
R is configured in NRSE input mode, each
channel uses only its positive AI pin. This pin connects to the positive terminal
of the onboard instrumentation amplifier. The negative input of the
instrumentation amplifier on each AI channel connects internally to the
AISENSE input pin.
Table 2-1.
Ideal Output Code and AI Voltage Mapping (Continued)
Input Description
AI Voltage
Output Code (Hex)
(Two’s Complement)
Output
Code
32,768
----------------------------------
10.0 V
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Summary of Contents for NI 781 R Series
Page 1: ...PXI 7842...
