Solution
NPLC (Number of Power Line Cycles)
NPLC stands for Number of Power Line Cycles. NPLC is a measurement term that indicates the accuracy with which a voltage or current is displayed on a device such as a digital multimeter. When determining the value of a DC signal, AC noise is often present from power lines. Since this noise is periodic, integrating the DC signal over one power line cycle can help eliminate this noise. For a power line cycle of 1, the power line frequency is 60 Hz (16.67 ms) for the United States (US) and 50 Hz (20 ms) for other countries.
Aperture time
Aperture time is the period during which the ADC is reading the input signal. Aperture time is based on time, and it is a concept similar to NPLC. NPLC is defined by power line cycles, and the aperture time is defined as time.
Relationship between NPLC (or aperture time) and reading rate
If you want to measure a signal, you should wait for the aperture time and the setting time until the signal is measured. As shown in the specification sheet below, the shorter the aperture time, the larger the reading rate. In conclusion, the shorter the aperture time, the shorter the setup time, which leads to an increase in the number of samples that can be read.
Note: This table is the specification of the PXI-4065. Other DMM modules may have different values, so please refer to each module's specification.