Encoder what you should know

An encoder is a device that compiles or converts a signal (such as a bit stream) or data into a signal that can be used to communicate, transmit, and store. The encoder converts the angular displacement or linear displacement into electrical signals. The former is called the encoder and the latter is called the encoder. According to the readout method, the encoder can be classified into contact type and non-contact type; according to the working principle, the encoder can be divided into two types: incremental type and absolute type. Incremental encoders convert the displacement into a periodic electrical signal, then convert this electrical signal into a counting pulse, and use the number of pulses to indicate the magnitude of the displacement. Each position of the Absolute Encoder corresponds to a definite digital code, so its indication is only related to the starting and ending positions of the measurement, and has nothing to do with the middle process of the measurement. An encoder is a device that compiles or converts a signal (such as a bit stream) or data into a signal that can be used to communicate, transmit, and store. The encoder converts the angular displacement or linear displacement into electrical signals. The former is called the encoder and the latter is called the encoder. According to the readout method, the encoder can be classified into contact type and non-contact type; according to the working principle, the encoder can be divided into two types: incremental type and absolute type. Incremental encoders convert the displacement into a periodic electrical signal, then convert this electrical signal into a counting pulse, and use the number of pulses to indicate the magnitude of the displacement. Each position of the absolute encoder corresponds to a definite digital code, so its indication is only related to the starting and ending positions of the measurement, and has nothing to do with the middle process of the measurement.

The encoder main classification encoder can be classified as follows.

1. According to the different types of engraving method of the code wheel (1) Incremental type: It is to send a pulse signal (also has a positive cosine signal)
The encoder then subdivides it, chopping out higher-frequency pulses, typically A-phase, B-phase, and Z-phase outputs. Phase A and Phase B are mutually delayed by 1/4 cycle pulse output, depending on the delay relationship. Positive and negative can be distinguished, and by taking the rising and falling edges of phase A and phase B, it is possible to perform 2 or 4 frequency multiplication; Z phase is a single-turn pulse, ie, one pulse per circle.
(2) Absolute value type: It is the corresponding circle, each angle of the reference sends a unique binary value corresponding to the angle, and the external circle device can record and measure multiple positions.
2, according to the type of signal output is divided into: voltage output, open collector output, push-pull complementary output and long drive output.
3, classified by encoder mechanical installation type (1) Shaft type: There are shaft type can be divided into clamping flange type, synchronous flange type and servo installation type.
(2) Shaft type: Shaft type can be divided into half-empty, full-empty and large-caliber.
4, the encoder works can be divided into: photoelectric, magnetic and contact brush type.
Encoder Common Fault Editing 1. The encoder itself is faulty: it means that the encoder itself has a fault.
The encoder causes it not to generate and output the correct waveform. In this case, replace the encoder or repair its internal components.
2, the encoder connection cable failure: This failure occurs the highest probability, often encountered in maintenance, should be a priority factor. Usually the encoder cable is open circuited, short-circuited or poorly connected. In this case, replace the cable or connector. Special attention should also be paid to whether it is due to the tightness of the cable and the looseness caused by loosening or disconnection. In this case, the cable must be clamped.
3, the encoder +5V power supply down: refers to +5V power supply is too low, usually not lower than 4.75V, caused too low due to power supply failure or power transmission cable resistance is too large and cause losses, then need to repair power Or replace the cable.
4. Absolute encoder battery voltage drop: This type of fault usually has clear alarms.
The encoder needs to replace the battery at this time. If the memory of the reference position is lost, the reference point operation must be performed again.
5, the encoder cable shield line is not connected or off: This will introduce interference signals, make the waveform unstable, affecting the accuracy of communication, must ensure reliable welding shield and grounding.
6. Loose installation of the encoder: This kind of fault will affect the accuracy of the position control, resulting in the positional deviation of the stop and the movement being overdone. Even the servo system overload alarm will be generated just after the power is turned on. Please pay special attention.
7, grating pollution This will reduce the signal output amplitude, must use a cotton wool stained with anhydrous alcohol to gently clean the oil.
3 Installation Mechanical Installation Using an Edit Absolute Rotary Encoder Use:
Absolute rotary encoders are mechanically mounted with high-speed and low-speed mountings.
Encoder-assisted mechanical installation and other forms.
High-speed end installation: Installed on the end of the motor shaft (or gear connection). The advantage of this method is its high resolution. Because there are 4096 turns of the encoder, the number of rotations of the motor is within this range, and it can be increased by using a full range. Resolution, the disadvantage is that the moving object through the reduction gear, back and forth gear gap error, generally used for one-way high-precision control and positioning, such as roll gap control. In addition, the encoder is directly installed on the high-speed end, and the motor shake must be small, otherwise it is easy to damage the encoder.
Low-speed installation: After installing in the reduction gear, such as the shaft end of the hoisting wire rope reel or the shaft end of the last reduction gear, this method has no gear return clearance. The measurement is more direct and the precision is higher. This method generally measures the length Distance positioning, such as various lifting equipment, feeding trolley positioning, etc.
Auxiliary mechanical installation:

Commonly used rack and pinion, chain belt, friction wheel, rope collection machinery.
4 Wiring Method Editing The rotary encoder is a photoelectric rotary measuring device that directly converts the measured angular displacement into a digital signal (high-speed pulse signal).
The encoder is divided into the signal principle, an Incremental Encoder and an absolute encoder.
We usually use an incremental encoder. The output pulse signal of the rotary encoder can be directly input to the PLC. The pulse signal of the rotary encoder can be counted by the PLC high-speed counter to obtain the measurement result. Different types of rotary encoders, the output pulse phase is also different, some rotary encoder output A, B, Z three-phase pulse, and some only A, B phase two, the simplest only A phase.
The encoder has 5 leads, of which 3 are pulse output lines, 1 is the COM end line, and 1 is the power line (OC gate output type). The power supply of the encoder can be an external power supply, or it can directly use the PLC's DC24V power supply. The "-" side of the power supply is connected to the COM side of the encoder, and the "+" is connected to the power supply side of the encoder. The COM terminal of the encoder is connected to the PLC input COM terminal. The A, B and Z two-phase pulse output lines are directly connected to the input terminals of the PLC. A and B are pulses with a phase difference of 90 degrees. The Z-phase signal rotates only once around the encoder. A pulse is usually used as the basis for the zero point. Pay attention to the response time of the PLC input when connecting. The rotary encoder also has a shielded wire. When using it, the shielded wire should be grounded to improve the anti-interference performance.