Waveform Acquisition Measurement Cycle
The NI 4070/4071/4072 waveform measurement cycle is made up of several phases: settling time, waveform acquisition phase, Auto Zero, and ADC calibration. Refer to the figure below for relative timing of these phases. The length of the waveform measurement phase is determined by the selected sample rate and number of points. Generally the settling time is selected by the device driver based on the specified function and range. This value can also be independently controlled. Refer to Configuring Measurement Timing for more information.
An internal switch time is required to configure the analog circuitry of the NI 4070/4071/4072 for the next measurement. Default settling times also precede both ADC calibration and Auto Zero. These settling times are not user programmable and are optimized in the design.
When you enable ADC calibration, gain drift errors are removed from the waveform data. At higher speeds, the lower resolution measurements make ADC calibration unnecessary.
Auto Zero removes offset from the waveform data. An Auto Zero measurement is taken and stored. This offset is subtracted from each point.