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Chapter 2 Hardware Overview of the NI 7831R
NI 7831R User Manual 2-4 ni.com
Input Modes
The NI 7831R 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 7831R AI range is fixed at ±10 V.
Table 2-1. Ideal Output Code and AI Voltage Mapping
Input Description AI Voltage
Output Code (Hex)
(Two’s Complement)
Full-scale range –1 LSB 9.999695 7FFF
Full-scale range –2 LSB 9.999390 7FFE
Midscale 0.000000 0000
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 7831R
Input Mode Description
DIFF When the NI 7831R 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 7831R 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 7831R 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.
Output Code
32,768
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10.0 V×