Rotary encoder is used to measure the rotational speed of device. It is divided into single output and dual output two kinds. Technical parameters are mainly each pulse number (dozens to several thousand), and the power supply voltage, etc. Single-channel output refers to the output of the rotary encoder is a set of pulses, and dual output rotary encoder output pulse phase difference of 90 degrees, the two groups in the two groups of pulse not only can measure the rotational speed, also can judge the direction of rotation.

The distinction between the incremental encoder and absolute encoder

Encoder, such as signal principle to points, with incremental encoder, absolute encoder.

Incremental encoder (rotation)

Working principle:

By A central shaft of light code disc, on which there are circular and dark scribed line, have read photoelectric emission and receiving devices, obtain four groups of sine wave signal is combined into A, B, C, D, each sine wave 90 degree phase difference (as opposed to A cycle of 360 degrees), will reverse, C, D signal superimposed on A, B two phase, can strengthen stability of signal; Every turn output another Z pulse to represent a zero reference.

Because of A, B two phase difference of 90 degrees, but only through A phase in the former or B phase in the former, with forward and inversion of discriminant encoder, through the zero pulse, encoder zero reference can be obtained.

Encoder code disc material with glass, metal, plastic, glass encoder is in the deposition of thin scribed line on the glass, its thermal stability, high precision, metal encoder directly to scribe lines and impassability, non-friable, but because has certain thickness of metal, precision is limited, its thermal stability is an order of magnitude worse than glass, plastic encoder is economical, its cost is low, but the accuracy and thermal stability, life is less.

Resolution - encoder per 360 degrees offer much or dark scribed line called resolution, also known as the analytical index, or say how many line directly, generally at every turn dividing line 5 ~ 10000.

Signal output:

Signal output sine wave (current or voltage), square wave (TTL, HTL), open collector (PNP and NPN), push-pull type A variety of forms, including TTL for long term differential drive (symmetry A, A -, B, B -, Z, Z) -, HTL also calls the push-pull type, push-pull output, encoder signal receiving device interface should correspond to the encoder.

Signal connection - encoder pulse signal general connection counter, PLC, computer, PLC and computer connection module with low speed module with high speed module, have low have high switch frequency.

Single-phase connection, such as used in the single direction count, the direction of velocity.

A. two connected for forward and reverse counting, direction and speed.

A, B and Z three-phase connection, used to refer to A fixed position measuring.

- A, A, B, B -, Z, Z - links, due to the negative signal connection with symmetry, current electromagnetic field for cable contributions to 0, attenuation minimum, anti-interference, best can transmit far distance.

For TTL with symmetric negative signal output of the encoder, the signal transmission distance up to 150 meters.

For HTL with symmetric negative signal output of the encoder, the signal transmission distance up to 300 meters.