Encoder is a kind of measuring device, which mainly converts pulse signal into data signal for people to read. Users choose different types of encoders with different application values. Besides, when using the encoder, people need to pay more attention to the wiring to ensure the normal measurement of the equipment.
Figure 1: Wiring of Autonics rotary encoder.
1. Key Points of Encoder Wiring
1.1 Correct Wiring
When you wire the encoder for the first time, it’s possible to result in line access errors or damage of equipment. If you are not familiar with the wiring, consult a professional person.
1.2 Understand Different Types of Lines
There are many different kinds of encoder lines. There are five leads, including three pulse output lines, one power line and one com terminal line.
When selecting the wire, the user must first know what each line is, so as to connect correctly, and ensure that there is no problem with the encoder circuit. Therefore, you can avoid problems in the use of the equipment and make accurate measurement.
Figure 2: Different types of encoder wiring lines.
1.3 Firm Connection
Despite no error in wiring, it’s possible that the wiring is not firm, resulting in a variety of problems in the circuit. What’s worse, it may lead to faults in operation.
The wiring of encoder seems simple, but it is necessary for users to be careful.
2. Wiring Method of Rotary Encoder
By counting the output pulse value of the equipment, with the PWM technology, the speed adjustment can be realized, so as to judge the direction of rotation. At present, rotary encoder types are often used in the industry, including photoelectric, angular speed, displacement and circuit output type.
Using rotary encoder, the output signal is transmitted to PLC high-speed counter through output pulse signal that is counted. In order to ensure the accuracy of signal transmission, it is necessary to confirm the effective connection of each point of equipment.
2.1 Check the Leads According to the Encoder Type
The number of encoder leads of different models is different. Generally, there are 5 leads for rotary encoder.
Each lead plays different roles. Three of them are pulse output lines, one is com port wire, and the other is power connection wire which is also known as OC output type. There is external power supply in rotary encoder. When you connect the wires, you can use the connection wire of COM directly, or PLC power cord. This depends on the actual situation.
Figure 3: KOYO rotary encoder with 300P/R wiring wire.
2.2 Positive and Negative Wiring
There are both positive and negative ends of power supply. It is necessary to ensure the connection between the negative end and COM, as well as negative end and encoder power port.
As shown previously, there are three pulse output lines in the rotary encoder, so the ends of three lines A, B, Z need to be connected to PLC.
3. Wiring Method of Motor Encoder
Encoder outlet methods include side outlet and rear outlet. If the wiring is wrong, it will damage the internal circuit of the encoder, affecting the use.
Figure 4: Dynapar motor encoder models.
Here are 5 best practice methods of wiring motor encoders.
In order to reduce noise interference, try to shorten the distance when wiring.
The motor encoder should be turned off. If the power supply is turned on, and the output wire contacts the power supply, the output circuit may be damaged.
When the wire is extended, due to the influence of the conductor resistance and the capacitance, the rise and fall time of the waveform are prolonged. It is easy to produce interference (crosstalk) between the signals. Therefore, use wires with low resistance and low capacitance between the wires (twisted pair, Shielded wire).
The extended wire should be shorter than 10m. The distribution capacity of the wire, the rise and fall time of the waveform will be longer. Use a Schmitt loop to shape the waveform.
If it is wired in parallel with the high-voltage line and power line, it will be induced to cause malfunction and damage, so separate them.
The encoder shaft is divided into: 6MM, 8MM, 10MM, 12MM, 14MM, 25MM. The accuracy of the encoder should be set according to the site.
4. Wiring Method of Switch Encoder
The switch encoder is also known as rotary encoder or chip encoder. Although their names are different, they are basically the same products. At present switch encoder is used widely.
Figure 5: Fanuc switch encoder A860-0308-T111.
4.1 Working Principle
When the switch encoder rotates, there will be corresponding pulse signal output. The rotation direction of the encoder can be judged by the increase or decrease of the number of pulses, which needs to be realized with the help of the rear direction judging circuit and counter.
The counting starting point of the encoder can be set at will, and the infinite accumulation and measurement of multiple circles can be done at the same time.
When a pulse Z signal is sent out for each revolution, a pulse signal will be output as the reference mechanical zero position. Therefore, when the pulse signal is fixed, in order to improve the resolution of the encoder, the two-way signals of A and B with 90 degree phase difference are operated, that is, frequency doubling of the original pulse number.
4.2 Method of Wiring
Generally, the switch encoder has five pin terminals. The first three pin terminals are A, B and Z phase pulse output lines, and the others are COM and power line terminal.
The wiring method of the encoder is to connect the power supply negative end with the COM, and then the positive end is connected with the power supply end. Connect the COM of the encoder with that of the PLC, and finally connect the A, B, Z phase pulse output line terminals with the input end of the PLC.
5. Wiring Method of Photoelectric Encoder
Photoelectric encoder is generally used to realize signal output of the motor. This type of encoder can be divided into incremental encoder and absolute encoder according to signal principle.
For the use of photoelectric encoder, users should understand several aspects about wiring to ensure the normal operation of the equipment.
It’s possible to make mistakes while wiring, resulting in the failure of equipment. Only the standardized wiring can guarantee the application value of the encoder.
Figure 6: Photoelectric encoder and wires.
Wiring requirements of photoelectric encoder.
Understanding of wiring port: different wiring ports with different functions, which must be cleared to ensure correct wiring.
Wiring safety: Before wiring, the user should turn off the equipment and keep it in a state of no current to avoid electric shock accident during wiring. After the wiring is completed, the encoder works.
Wiring fixed: wiring must be fixed, in order to make the encoder work well. Many users often ignore the stability of the wiring when wiring, resulting in the interruption of the encoder during working, leading to failure of the equipment. Therefore, it is necessary to check whether the wiring is firm.
Wiring specification: we should follow the specification of wiring. Only with standardized wiring, the encoder can operate as expected. However, many users often ignore the wiring specification, resulting in complex lines. Once the equipment is damaged, the normal detection will be affected. So it is important to wire the encoder with specification.
6. How to Correctly Connect the Encoder?
Correct wiring of the encoder is very important. Here are the five steps.
Correct wiring is very important. Brown wire is connected to positive pole of power supply, blue wire is connected to negative pole.
Black wire is connected to input 0.00, white wire is connected to input 0.01, orange wire is connected to input 0.04. COM of PLC is connected to positive pole.
The red wire is connected to the positive pole of the power supply, the black wire is connected to the negative pole.
The brown wire input is 0.00, the orange wire input is 0.01, the yellow wire input is 0.02, the green wire input is 0.03, the blue wire input is 0.04, the purple wire input is 0.05, the gray wire input is 0.06, the white wire input is 0.07, the pink wire input is 0.08, and the COM of PLC is connected to the positive pole.
The red wire is connected to the positive pole of power supply, the black wire is connected to the negative pole.
The brown wire is connected to input 0.00, the orange wire is connected to input 0.01, the yellow wire is connected to input 0.02, the green wire is connected to input 0.03, the blue wire is connected to input 0.04, the purple wire is connected to input 0.05, the gray wire is connected to input 0.06, the white wire is connected to input 0.07, the pink wire is connected to input 0.08. And the com of PLC is connected to the negative pole.
The brown wire is connected to the positive pole of the power supply, the blue wire is connected to the negative pole. The black wire is connected to the input 0.00, the white wire is connected to the input 0.01, the orange wire is connected to the input 0.04. And the COM of PLC is connected to the negative pole.
The black wire is connected to A0 +, the black red edge wire is connected to A0 -, the white wire is connected to B0 +, the white red edge wire is connected to B0 -, the orange wire is connected to Z0 +, the orange red edge wire is connected to Z0 -. The brown wire is connected to the power supply + 5V, and the blue wire is connected to the power supply 0V.