Analog Output >> General Properties >> DAC >> Resolution Value

NI-DAQmx C Properties

Analog Output >> General Properties >> DAC >> Resolution Value

Data Type: float64
Description: Indicates the resolution of the digital-to-analog converter of the channel. This value is in the units you specify with Resolution Units.
Restrictions: Not Settable

You can get this property using:
  DAQmxGetAOResolution