Single and Multi Turn Rotary encoders Single turn industrial encoders are systems that measure absolute positions for one turn of the shaft, i.e for 360°. After one turn the measuring range is ex- ceeded and loops back to the starting value. How- ever, in many applications several turns of the shaft must be distinguished. In these cases, multi turn encoders will keep track of the angle position of the shaft while also providing code information about the number of turns.

ENCODERS

Absolute Rotary Encoders Absolute rotary encoders are capable of providing unique position values from the moment they are switched on as well as immediately after a power loss. This is accomplished by scanning the position of a coded material. All positions in these systems correspond to a fixedcode. Even movements that occur while the system is without power are translated into accurate posi- tion values at once when the encoder is powered up again. Incremental Rotary Encoders Incremental encoders measure angle values by counting a material with a periodic pattern, starting from an arbitrary origin. This measuring method does not inherently render absolute positions for a measured signal. Initial homing to a reference point is therefore inevitable in all positioning tasks, both upon startup of the control system and whenever power to the encoder has been interrupted.