The Voltmeter uses the oscilloscope channels. When the Voltmeter is running, it takes control over the physical oscilloscope channels and the Oscilloscope instrument state is “busy”. Similarly, when the Oscilloscope is started, the Voltmeter is stopped. The oscilloscope sweeps are windowed and DC, AC, and DC RMS values calculated. For the True RMS value, the same acquisition is used as for the DC voltage, and the value is calculated with the formula Sqrt( sum( xi ^ 2 ) / N ). The AC RMS value is calculated with the formula Sqrt( sum( (xi - dc) ^ 2 ) / N ).