Sample Clock >> Rate

NI-DAQmx C Properties

Sample Clock >> Rate

Data Type: float64
Description: Specifies the sampling rate in samples per channel per second. If you use an external source for the Sample Clock, set this input to the maximum expected rate of that clock.

You can get/set/reset this property using:
  DAQmxGetSampClkRate
  DAQmxSetSampClkRate
  DAQmxResetSampClkRate