Absolute rotary encoders measure actual position by generating  unique digital codes or bits (instead of pulses) that represent the encoder’s actual position. Single turn absolute encoders output codes that are repeated every full revolution and do not output data to indicate how many revolutions have been made. Multi-turn absolute encoders output a unique code for each shaft position through every rotation, up to 4,096 revolutions. Unlike incremental encoders, absolute encoders will retain correct position even if power fails without homing at startup.