Devices that support an external voltage reference enable you to maximize the resolution of your device. If the voltages you want to generate do not exceed a certain level and you can supply an external reference voltage at that level, you achieve your device's maximum resolution. The external reference voltage settings are available as a Channel property in the Analog Output»General Properties»DAC»Reference Voltage.

You also can use external reference voltages to apply a gain to a DC voltage or to a time-varying waveform. For example, set your external reference voltage level to 1.0, and write a sine wave buffer with values from -1.0 to +1.0 V. When you apply an actual reference voltage of 2.0 V, your signal jumps to ±2 V in amplitude. Increasing the reference voltage level to 3.0 again jumps the signal to ±3 V. Applying a reference voltage level of 0.0 V immediately flat-lines your time-varying voltage signal at 0.0 V.

The terminal you use for external reference sources varies depending on your device.

AO Reference and Offset Support for PXIe-6381/6383 (X Series)

For PXIe‑6381 and PXIe‑6383, analog output channels support both Reference and Offset selection (similar to M‑Series AO behavior). Use the NI‑DAQmx AO Reference and AO Offset properties to configure these options. Refer to the device specifications for supported ranges.