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　　Currently, the rotary encoder has been widely used, many of my friends want to know the working principle of rotary encoders, rotary today liters Electronic give you explain in detail under the encoder works.
　　Rotary encoder zero reference position
　　It consists of a center axis of the optical encoder, which has a ring through the dark of the engraved lines, optoelectronic transmitting and receiving device to read, get a sine wave signals into four groups A, B, C, D, each sine wave phase difference of 90 degrees (with respect to a cycle of 360 degrees), the C, D inverted signal, superimposed on a, B on the two-phase, can enhance stabilization signal; output per rotation other Z-phase pulse to represent a zero reference bit.
　　Since the A, B two-phase difference of 90 degrees, the first phase A or B by comparing the first phase, in order to determine the encoder forward and reverse, the zero pulse can be obtained encoder zero reference position.
　　Encoder materials
　　Encoder code disc material glass, metal, plastic, glass code discs are deposited thin engraved lines on the glass, good thermal stability, high accuracy, metal code disc directly through the barrier and engraved lines, non-friable, However, since the metal has a certain thickness, there are restrictions precision, thermal stability is necessary an order of magnitude worse than glass, plastic code disc is a economical, low cost, but the accuracy, thermal stability and life are to be worse .
　　Encoder resolution
　　Resolution - 360 degrees per encoder rotation through or how much dark groove called the resolution, also known as analytic indexing, or direct say how much wire, usually 5 degrees per rpm to 10,000 lines.
　　Encoder signal output
　　There are a sine wave output signal (current or voltage), square wave, open collector (PNP, NPN), push-pull many forms, as long TTL differential drive (symmetric A, A-; B, B-; Z, Z -), HTL, also known as push-pull, push-pull output encoder signal receiving device interface should correspond with the encoder.
　　The encoder signal connection
　　Signal connector module encoder pulse signal typically connected counter, PLC, computer, PLC and computer are connected to high-speed and low-speed module module of the points, with a high switching frequency is low.
　　Such as single-phase connection for unidirectional counting speed in one direction.
　　A.B two-phase connection for positive and negative counting, and speed to determine the pros and cons.
　　A, B, Z-phase connection for position measurement with a reference bit correction.
　　A, A-, B, B-, Z, Z- connection, the connection with a symmetrical negative signal in the subsequent differential input circuit, the common mode noise rejection, just take a useful differential mode signal, so the anti interference ability, can transmit far distance. For TTL signal output with symmetric negative encoder signal transmission distance up to 150 meters.
　　Note the use of the rotary encoder
　　Use the rotary encoder should be avoided during a big impact, since the rotary encoder constituted by a precision devices, when subjected to a large impact, may damage the internal function, it should be paid to use.