An encoder is a device (transducer) that is used to convert rotary or linear motion into useful information. The primary parameters determined are speed, rate, velocity, distance, position, or direction. A typical application will use one or more of these parameters as feedback to the controller in a motion control system.

British Encoder's rugged and reliable encoders are particularly suited to the most challenging applications in process and machine control, motor feedback, factory automation, robotics, web tensioning, etc. In addition to these applications, rotary optical encoders can also provide electronic commutation in brushless servo systems.

An 'absolute' encoder maintains position information when power is removed from the system. The position of the encoder is available immediately on applying power. The relationship between the encoder value and the physical position of the controlled machinery is set at assembly; the system does not need to return to a calibration point to maintain position accuracy.