It is a rotary sensor that converts rotational displacement into a series of digital pulse signals that can be used to control angular displacement and can be used to measure linear displacement if the encoder is combined with a gear or screw.
Encoder generated by the CNC CNC control system, programmable logic controller PLC, control systems to deal with. These sensors are mainly used in the following areas: machine tools, materials processing, motor feedback systems and measurement and control equipment. In the ELTRA encoder angular displacement conversion using photoelectric scanning principle. The reading system is based on the rotation of a radial indexing plate consisting of alternating translucent and opaque windows. The system is illuminated vertically with an infrared light source so that the light projects the image on the plate onto the receiver’s surface. The receiver is covered with a layer of gratings, called collimators, that have the same window as the disc. The receiver’s job is to sense the light changes caused by the rotation of the disc and then convert the light changes into corresponding electrical changes. Generally, the rotary encoder can also get a speed signal, which is fed back to the inverter to adjust the inverter output data. Fault phenomenon: 1, the rotary encoder is bad (no output), the inverter can not work properly, become very slow speed, and while the inverter protection, display “PG off” … joint action to work. To make the electrical signal rise to a high level, and produce square wave pulse without any interference, this must deal with with the electronic circuit. Encoder pg wiring and parameter vector The connection between the inverter and encoder pg must correspond to the type of encoder pg. In general, the encoder pg model sub-differential output, open collector output and push-pull output of three, the signal transmission mode must take into account the pg card converter interface, so choose the right pg card model or set reasonable.

Encoders are generally divided into incremental and absolute, and they exist the biggest difference: in the case of incremental encoder, the position is determined from the number of pulses counted from the zero mark, and absolute encoder position is Determined by the reading of the output code. In a circle, the readings of the output code are unique for each location; therefore, the absolute encoder is not decoupled from the actual location when the power is off. If the power is turned on again then the position reading is still current and valid; unlike incremental encoders, the zero mark must be searched.
Encoder manufacturers produce series are all, are generally dedicated, such as elevator dedicated encoder, machine-specific encoder, servo motor-specific encoder, etc., and the encoder is intelligent, there are a variety of parallel Interface can communicate with other devices.
Encoders are devices that convert angular or linear displacements into electrical signals. The former became a code wheel, the latter called yardstick. According to read out the encoder can be divided into contact and non-contact two. Contact using brush output, a brush contact conductive area or insulation to indicate the status of the code is “1” or “0”; non-contact to accept the sensitive element is a photosensitive element or magnetic sensor, the use of photosensitive elements The light and light tight areas indicate whether the status of the code is “1” or “0”.

According to the principle of encoder can be divided into two types of incremental and absolute.
Incremental encoder is the displacement is converted into periodic electrical signals, then the electrical signal into a count pulse, with the number of pulses that the size of the displacement. Each position of the absolute encoder corresponds to a specific digital code, so its indication depends only on the start and end position of the measurement, regardless of the intermediate process of the measurement.
Rotary incremental encoders output pulses as they turn, know their position with the counting device, and remembers the position with the internal memory of the counting device when the encoder is stationary or powered down. In this way, when the power outage, the encoder can not have any movement, when the call work, the encoder output pulse, there should be no interference and loss of pulse, otherwise, the counting device memory zero will shift, and this bias The amount of migration is unknown and can only be known if the wrong production result appears. The solution is to increase the reference point, the encoder every reference point, the reference position correction into the memory location of the counting device. Before the reference point, the accuracy of the position can not be guaranteed. To this end, in industrial control there is every operation to find a reference point, boot and other methods. This encoder is determined by the encoder mechanical position, it is not affected by power outages, interference.
Absolute encoder by the mechanical position of each position uniqueness, it does not need to remember, no need to find a reference point, and do not have to count, when the need to know the location, when to read its location. In this way, the encoder anti-jamming characteristics, data reliability has greatly improved.

Because absolute encoders are obviously superior to incremental encoders in positioning, they have been increasingly used in industrial control positioning. Absolute encoder because of its high precision, the output bit more, such as still use parallel output, each of its output signal must ensure that the connection is good, for more complex conditions but also isolated, the number of connecting cable core from Therefore, the absolute encoder in the multi-digit output type, the general selection of serial output or bus type output, the absolute encoder serial output produced in Germany is the most commonly used SSI (synchronous serial Line output).
Multi-turn absolute encoder. Encoder manufacturers use the principle of clock gear machinery, when the center code wheel is rotated, another set of code wheels (or sets of gears and sets of code wheels) is driven through gears to increase the number of turns on the basis of the single-turn code Coding to expand the measuring range of the encoder. Such an absolute encoder is called a multi-turn absolute encoder. It is also determined by the mechanical position coding. Each position code is unique and does not need to be memorized. Another advantage of the multi-turn encoder is that due to the large measurement range, the actual use is often more affluent, so you do not need to find a little bit of work in the installation, the starting point of a middle position on it, and greatly simplifies the installation and commissioning. The advantages of multi-turn absolute encoders in terms of length positioning are obvious and have been increasingly used in industrial control positioning.

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