From a center axis of the photoelectric encoder, which have a ring-pass, dark groove, there are optical transmitting and receiving device reads the sine-wave signal was combined into four groups A, B, C, D difference of 90 for each sine wave degree phase difference (as opposed to a cycle of 360 degrees) will be C, D signals reverse, superimposed on the A, B two-phase, it can enhance the stability of the signal; the other output of each switch to a Z-phase pulse to represent the zero reference position.
    Because A, B two-phase difference between the 90 degrees, can be the first by comparing the A or B relative to the previous phase in order to determine the encoder is being transferred with the reverse, through zero pulse, get the encoder zero reference position.
    Encoder code plate materials are glass, metal, plastic, glass code disk is deposited on glass thin engraved lines, its thermal stability, high accuracy, metal encoder directly to the pass and unreasonable carved lines, non-friable, However, there is a certain thickness of metal, precision, there are restrictions on the thermal stability is necessary to more than an order of magnitude difference between glass, plastic yards disk is economical, and its low cost, but the precision, thermal stability, life have to be some difference .
    Resolution - the encoder to rotate 360 degrees each of the pass or how much dark groove called the resolution, also known as analytic indexing, or direct that the number of lines, the general sub-degree turn in every 5 ~ 10000 lines.
    Signal Output:
There sine wave signal output (current or voltage) square wave (TTL, HTL) open collector (PNP, NPN) push-pull variety of forms, including TTL for the long-term differential drive (symmetric AA-; BB-; ZZ-) HTL is also said that a push-pull, push-pull output, encoder signal receiving device interface should correspond with the encoder.
    Signal Connection - encoder pulse signal is normally connected to the counter, PLC, computer, PLC and computer connectivity module has low-speed modules and high-speed modules of the points, a low switching frequency high.
    Such as single-phase connections, for a one-way counts, one-way speed.
    AB two-phase connections, for the positive and negative counting, to determine the positive and negative direction and speed.
    A, B, Z-phase connections, with reference to place the amendment for the position measurement.
    A, A-, B, B-, Z, Z-link, due to the negative signals with a symmetric connection, the current contribution for the cable electromagnetic field is 0, the minimum attenuation, anti-jamming best, can be transmitted farther distance.
    For the TTL with the symmetry of the negative signal output encoder, the signal transmission distance up to 150 meters.
    For the HTL with the symmetry of the negative signal output of the encoder, the signal transmission distance up to 300 meters.