Incremental encoders are generally divided into three types: single-channel incremental encoders, dual-channel incremental encoders, and three-channel incremental encoders.
Single channel incremental encoder:
This type of encoder has only one pair of optocouplers inside, and only one pulse sequence can be generated. Generally, this is three lines.
Dual channel incremental encoder:
The encoder is divided into A and B phases, and there are two pairs of optocouplers inside, which can output two independent pulse sequences with a phase difference of 90 degrees. The two-way pulse lead and the lag relationship are just the opposite when forward and reverse. Generally this is 4 lines.
Three-channel incremental encoder:
In addition to the two pairs of optocouplers with dual-channel incremental encoders, the encoder has a transparent section in the other channel of the pulse code disc. Each revolution, one pulse is output. This pulse is called Z. The phase zero pulse is used as the system clear signal, or the origin of the coordinates to reduce the accumulated error of the measurement. Usually 6 lines.
Encoder signal output:
The signal output has sine wave (current or voltage), square wave (TTL, HTL), open collector (PNP, NPN), push-pull type, of which TTL is long-line differential drive (symmetric A, A-; B, B -; Z, Z-), HTL is also called push-pull, push-pull output, the signal receiving device interface of the encoder should correspond to the encoder.
Signal connection—The pulse signal of the encoder is generally connected to the counter, plc, computer, PLC and computer connected modules have low speed module and high speed module, the switching frequency is low and high.
Such as single-phase connection, for single-direction counting, single-direction speed measurement.
A.B two-phase connection, used for forward and reverse counting, judging forward and reverse and speed measurement.
A, B, Z three-phase connection for position measurement with reference position correction.
A, A-, B, B-, Z, Z-connection, due to the connection with a symmetrical negative signal, the current contributes to the electromagnetic field of the cable is 0, the attenuation is minimal, the anti-interference is optimal, and the long distance can be transmitted.
For TTL encoders with a symmetrical negative signal output, the signal can travel up to 150 meters.
For HTL encoders with a symmetrical negative signal output, the signal transmission distance can reach 300 meters.
weihao_law