An encoder is a sensor which turns a position into an electronic signal. There are two forms: *

Absolute encoder 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 analog or digital output signals. There are two main types of rotary encoder: absolute and increm ...

s give an absolute position value. *

Incremental encoder An incremental encoder is a linear or rotary electromechanical device that has two output signals, ''A'' and ''B'', which issue pulses when the device is moved. Together, the ''A'' and ''B'' signals indicate both the occurrence of and direction ...

s count movement rather than position. With detection of a datum position and the use of a counter, an absolute position may be derived. The position may be measured as either linear or angular position *

Linear encoder A linear encoder is a sensor, transducer or readhead paired with a scale that encodes position. The sensor reads the scale in order to convert the encoded position into an analog or digital signal, which can then be decoded into position by a di ...

, converts linear position to an electronic signal *

Rotary encoder 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 analog or digital output signals. There are two main types of rotary encoder: absolute and increm ...

, converts rotary position to an electronic signal

See also