Question

How to know the direction of absolute encoder ?

Answer 1

Encoders offer motion management data on position, count, speed and direction. As the encoder shaft rotates, output signals area unit made, proportional to the distance (angle) of rotation. The signal is also within the type of a sq. wave (for an progressive encoder) or an absolute measure of position (for an absolute encoder). Due to the performance and reliability advantages of the semi-conductor technology they incorporate, optical encoders are the preferred solutions in many common computer, industrial and automotive applications. Optical encoders additionally have the benefit of easy customization, are suitable to various environments, and suffer no effects from high levels of stray magnetic fields.
The basic construction of an incremental encoder is shown in attachment. A beam of sunshine emitted from AN semiconductor diode passes through a clear disk patterned with opaque lines and is picked up by a photodiode array. The Photo diode array (also called a photo sensor) responds by producing a sinusoidal waveform which is transformed in a square wave or pulse train. Incremental encoder, often called a tachometer, is normally used in systems that rotate in one direction only and require simple position and velocity information. Quadrature encoders have twin channels ( A and B ), phased 90 electrical degrees apart.
These 2 output signals verify the direction or rotation by sleuthing the leading or lagging signal in their section relationship.
Quadrature encoders offer terribly high speed bi-directional info for terribly advanced motion management applications. Incremental encoders can provides a once-per-revolution pulse (often referred to as index, marker, or reference) that happens at identical mechanical purpose of encoder shaft revolution. This pulse is on a separate output channel (Z) from the signal channel or quadrature outputs. The index pulse is usually wont to position motion management applications to a best-known mechanical reference. Resolution is a term used to describe the Pulses Per Revolution (PPR) for incremental encoders, or the total number of unique positions per revolution for an absolute encoder. Each incremental encoder contains a outlined variety of cycles that are generated for every full 360 degree revolution. These cycles ar monitored by a counter or motion controller and regenerate to counts for position or speed control. Absolute encoders generate a unique code word for every resolvable shaft angle (often called bits or pulse per revolution).