Analog Output; Connecting Analog Output Signals - National Instruments NI PXI-7831R User Manual

Chapter 2 Hardware Overview of the NI PXI-7831R

Analog Output

Output Description
Full-scale range –1 LSB
Full-scale range –2 LSB
Midscale
Negative full-scale range,
+1 LSB
Negative full-scale range
Any output voltage
Note If the output value for an AO channel is not specifically set by your VI then the AO
channel voltage output will be undefined.

Connecting Analog Output Signals

NI PXI-7831R User Manual
common-mode signals as long as V+
within their specified input ranges. Refer to Appendix A, Specifications,
for more information about input ranges.
The NI PXI-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 PXI-7831R to automatically load and run your VI when the system
powers on. This VI can then set the AO channels to the desired voltage
levels. Data written to the DAC is interpreted in two's complement format.
Table 2-3 shows the ideal AO voltage generated for a given input code.
Table 2-3. Ideal Output Voltage and Input Code Mapping
AO Voltage
9.999695
9.999390
0.000000
–9.999695
–10.000000
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 2-9 shows how to make AO connections to the NI PXI-7831R.
and V–
in
—
2-14
(input signals) are both
in
Input Code (Hex)
(Two's Complement)
7FFF
7FFE
0000
8001
8000
AO Voltage
×
32,768
------------------------------ -
10.0 V
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