AEMC L261 [ 2126.05] Simple Logger II AC/DC Voltage Data Logger, 600 V. The Simple Logger® II Model L261 is a one channel recording device powered by two alkaline batteries. Line tracking is performed such that 64 samples over one line cycle are taken. Frequency tracking is performed over the range of ±2Hz around the nominal line frequency 50 or 60Hz. Harmonic measurements are calculated from these 64 samples. Harmonics are only available from the Simple Logger® II Control Panel within the free DataView® software included with the unit. The Simple Logger® II records TRMS at a rate of up to eight times per second. The measurement process is performed no more than eight times per second. TRMS calculations are performed on a single line cycle. This means that the inputs are ignored between measurement intervals. The main advantage of the logger is its ability to perform a variety of recording tasks with easy and intuitive setup from a computer using DataView® software.