What parameters should be considered when selecting an encoder? What are the common faults?

An encoder is a device that compiles and converts signals (such as bit streams) or data into a signal form that can be used for communication, transmission and storage. The encoder converts angular displacement or linear displacement into electrical signals. The former is called a code disk and the latter is called a code ruler. According to the readout method, encoders can be divided into contact and non-contact types; according to the working principle, encoders can be divided into incremental and absolute types. The incremental encoder converts the displacement into a periodic electrical signal, and then converts the electrical signal into a counting pulse, and the number of pulses is used to indicate the size of the displacement. Each position of the absolute encoder corresponds to a certain digital code, so its indication is only related to the starting and ending positions of the measurement, but not to the intermediate process of the measurement.

Encoders are an integral part of mechanical equipment, converting rotary, linear or angular motion into digital signals for the control and monitoring of robots or industrial equipment. However, there are many parameters to consider when selecting an encoder to ensure that it performs optimally in a specific application while remaining stable and reliable.

Key parameters for encoder selection

1. Resolution: Resolution represents the minimum amount of motion that the encoder can detect, usually calculated in lines. In other words, the higher the resolution, the more accurate the encoder, but it also increases the cost.

2. Response speed: Response speed refers to the encoder's ability to respond when it detects motion, measured in microseconds. This is very important for applications that require fast response.

3. Output signal type: Encoder output signals are usually provided in analog or digital format, and we need to choose according to the specific application to ensure that the controller connected to the device can read the signal correctly.

4. Size and mechanical installation method: Size and mechanical installation method determine the installation position and method of the encoder on the equipment, so the space limitations and installation requirements of the equipment need to be considered.

5. Durability: Mechanical equipment is usually subjected to long-term operation and vibration, so the encoder needs to have sufficient durability and shock resistance to ensure that no failure occurs during operation.

In summary, encoder selection requires comprehensive consideration of the above key parameters and other factors such as power supply type and electrical interface. When we understand these parameters, we can choose the encoder that best suits our application to improve equipment operation efficiency and accuracy.

Common faults

1. Encoder fault: This means that the encoder itself has a component fault, which causes it to be unable to generate and output the correct waveform. In this case, the encoder needs to be replaced or its internal components need to be repaired.

2. Encoder connection cable failure: This failure has the highest probability of occurrence and is often encountered during maintenance. It should be the priority factor. Usually the encoder cable is broken, short-circuited or in poor contact. In this case, the cable or connector needs to be replaced. Special attention should also be paid to whether the cable is not fixed tightly, causing looseness and causing open welding or broken circuit. In this case, the cable needs to be clamped.

3. Encoder +5V power supply drops: It means that the +5V power supply is too low, usually not lower than 4.75V. The reason for the low power supply is power supply failure or power transmission cable resistance is too large and causes loss. At this time, the power supply needs to be repaired or the cable needs to be replaced.

4. Absolute encoder battery voltage drops: This fault usually has a clear alarm, and the battery needs to be replaced. If the reference point position memory is lost, the reference point return operation must be performed.

5. The encoder cable shielding wire is not connected or falls off: This will introduce interference signals, make the waveform unstable, and affect the accuracy of communication. The shielding wire must be reliably welded and grounded.

6. Loose installation of the encoder: This fault will affect the accuracy of position control, causing excessive position deviation during stopping and moving, and even a servo system overload alarm as soon as the machine is turned on. Please pay special attention.

7. Grating pollution will reduce the signal output amplitude. The oil stain must be gently wiped off with absorbent cotton dipped in anhydrous alcohol.

8. The high-speed end of the encoder is not aligned or installed too tightly: This will cause the encoder's ball bearing to wear and heat up, and the lubricating oil in the bearing will leak and contaminate the code disk, thereby affecting signal acquisition.