The output of incremental encoders provides information about the motion of the shaft, which is typically further processed elsewhere into information such as speed, distance and position. The output of absolute encoders indicates the current position of the shaft, making them angle transducers. There are two main types: absolute and incremental (relative). A rotary encoder, also called a shaft encoder, is an electro-mechanical device that converts the angular position or motion of a shaft or axle to an analog or digital signal.