Introduction of 3 types of incremental encoders

Incremental encoders are generally divided into 3 types: single-channel incremental encoder, dual-channel incremental encoder, and three-channel incremental encoder.

Single channel incremental encoder:

This kind of encoder has only 1 pair of photoelectric coupler, can only produce a pulse sequence, generally this kind is 3 lines.

Dual-channel incremental encoder:

This kind of encoder is divided into A and B phases. There are two pairs of photocouplers inside, which can output two sets of independent pulse sequences with a phase difference of 90 degrees. The relationship between the lead and lag of the two pulses in forward and reverse rotation is just opposite. Generally this is 4 lines.

Three-channel incremental encoder:

In addition to the two pairs of photocouplers with dual-channel incremental encoders inside the encoder, there is a light-transmitting section in the other grid channel of the pulse code disc, and one pulse is output per revolution. This pulse is called Z The phase zero pulse is used as the system reset signal or the origin of the coordinate to reduce the accumulated error of the measurement. Generally there are 6 lines.

The signal output of the encoder:

The signal output has sine wave (current or voltage), square wave (TTL, HTL), open collector (PNP, NPN), push-pull multiple forms, of which TTL is a long-line differential drive (symmetrical A, A-; B, B -;Z, Z-), HTL is also called push-pull and 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, and computer. The modules connected to the PLC and the computer are divided into low-speed modules and high-speed modules, and the switching frequency is low or high.

Such as single-phase connection, used for single direction counting and single direction speed measurement.

A.B two-phase connection, used for forward and reverse counting, judgment of forward and reverse and speed measurement.

A, B, Z three-phase connection, used for position measurement with reference position correction.

A, A-, B, B-, Z, Z- connections, due to the connection with symmetrical negative signals, the electromagnetic field contributed by the current to the cable is 0, the attenuation is the smallest, the anti-interference is the best, and it can be transmitted over a long distance.

For TTL encoders with symmetrical negative signal output, the signal transmission distance can reach 150 meters.

For HTL encoders with symmetrical negative signal output, the signal transmission distance can reach 300 meters.