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Chapter 2 Hardware Overview of the NI 7831R
© National Instruments Corporation 2-15 NI 7831R User Manual
Analog Output
The NI 7831R has eight 16-bit AO channels. The bipolar output range is
fixed at ±10 V. Some applications require that the AO channels power on
to known voltage levels. To set the power-on levels, you can configure the
NI 7831R to load and run your VI when the system powers on. This VI can
set the AO channels to the desired voltage levels. The VI interprets data
written to the DAC in two’s complement format. Table 2-3 shows the ideal
AO voltage generated for a given input code.
Note If your VI does not set the output value for an AO channel, then the AO channel
voltage output will be undefined.
Connecting Analog Output Signals
The AO signals are AO <0..7> and AOGND.
AO <0..7> are the eight available AO channels. AOGND is the ground
reference signal for the AO channels.
Figure 2-10 shows how to make AO connections to the NI 7831R.
Table 2-3. Ideal Output Voltage and Input Code Mapping
Output Description AO Voltage
Input 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 output voltage —
AO Voltage
10.0 V
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