Incremental rotary encoders convert shaft rotation into a train of electrical pulses on two channels, A and B, offset by 90 degrees, allowing a controller to determine both rotational speed and direction of travel. Many designs add a third Index or Z channel that outputs a single pulse per revolution for homing and reference positioning. Unlike absolute encoders, incremental types do not retain position information through a power loss - the controller must re-establish a reference point after power is restored, typically through a homing routine. This makes incremental encoders best suited to applications where relative motion, speed, and direction matter more than retained absolute position. Output signal formats include HTL (10-30V push-pull), TTL/RS422 differential line driver, NPN/PNP open collector, and SinCos analogue outputs, covering the input requirements of virtually all industrial drives and PLCs. Resolutions commonly range from 100 to 10,000 pulses per revolution, with higher-resolution variants available for precision applications. Mechanical mounting options include solid shaft (coupling-mounted), hollow shaft (direct mount), and blind hollow shaft (end-of-shaft mount) configurations, while internal sensing technology may be optical for higher accuracy or magnetic for superior contamination resistance. Housings in die-cast aluminium or stainless steel with IP65 to IP67 sealing handle typical plant conditions including dust, oil mist, and washdown exposure. Incremental rotary encoders are the standard choice for motor speed feedback, conveyor and drive speed monitoring, machine axis position counting, and process synchronisation wherever the cost-effectiveness and mechanical simplicity of incremental sensing outweighs the need for retained absolute position.
