Data loggers is a kind of measurement device that can be used to store data. They can record a wide variety of energy and environmental measurements including temperature, relative humidity, voltage, differential pressure, time-of-use (lights and motors), light intensity, water level, soil moisture, rainfall, wind speed and direction, pulse signals, and more.
This includes many data acquisition devices such as plug-in boards or serial communication systems which use a computer as a real time data recording system. However, most instrument manufacturers consider a data logger a stand alone device that can read various types of electrical signals and store the data in internal memory for later download to a computer.
Nowadays data loggers are becoming more and more small, battery powered, portable, and equipped with a microprocessor, internal memory for data storage. Some data loggers interface with personal computers or smart phones for set-up, control, and analysis.