incremental angle encoders

With incremental angle encoders and rotary encoders, the current position is determined by starting at a datum and counting measuring steps, or by subdividing and counting signal periods. Incremental encoders from HEIDENHAIN feature reference marks, which must be scanned after switch-on to reestablish the datum. Incremental rotary encoders with commutation signalssupply the angular shaft position value - without requiring previous traverse - with sufficient accuracy to correctly control the phases of the rotating field of a permanent-magnet three-phase motor.