6 Common Faults of Encoder?

Figure 1: Encoders from okmarts.

If motion control is important to your production, then your Encoder is one of the keys to your success. Encoders are exposed to shock, contaminants/oil, excess vibration, moisture, and high temperatures that regularly put their toughness to the test.

There’s a lot of encoders out there in industry. So, what are the common faults and how to deal with them?

1. Problem 1: No Output

Solution: No output may be a result of various factors. Steps can be taken to ensure the proper functionality of the encoder. No mechanical movement results in any signal being output from the encoder. To correct this issue, observe if the encoder is rotating. Verify all wring between the encoder and the driver/controller is correct and the appropriate voltage supply is used. Having loose connections or improper voltage supply may not allow the encoder to function properly. Finally, ensure the correct signal type (e.g. open collector, pull-up, line driver or push-pull) is being used for your application. If the problem persists, swap encoders, if possible, to determine if the encoder is the issue.

Figure 2: Wring of the encoder.

2. Problem 2: Unable to Find Index Pulse

Solution: The index pulse, or reference marker, is a once per revolution output of an encoder and is best found using an oscilloscope. Verify all the wiring between the encoder and the driver/controller is correct and the appropriate voltage supply is used. If that does not solve the issue, try lowering the RPM of the motor, as the driver/controller may not be able to identify the index pulse at very high RPM values.

Figure 3: Use an oscilloscope.

3. Problem 3: Count Output Indicates Incorrect Direction

Solution: If the count output indicates an incorrect direction then check for the wire configuration. See if any wires are reversed. If they are reversed, simply swap wires.

NOTE: If your application is using index, reversing the wire configuration causes the reference alignment to also change. If so, please make the appropriate changes to your application.

4. Problem 4: Encoder is not Rotating

Solution: When encoders are exposed in open environments, dust and debris particles may accumulate around the shaft. Simply clean the exposed area and ensure that there are not objects obstructing the encoder from rotating.

Figure 4: Cleaning the encoder.

5. Problem 5: Noise Interference

Solution: To improve the noise immunity of encoders it is strongly advised that no other electrical equipment be nearby or be kept at a fair distance. Encoder cables should also be shielded and proper wires should be grounded to minimize electrical noise.

6. Problem 6: Distorted or Incorrect Output

Solution: Distorted or incorrect output can be any combination of loose wiring connections, encoder output not compatible with driver/controller, electrical noise or improper alignment. Check for wire connections, compatibility issues with the encoder and the driver/controller, alignment of the encoder and the shaft to solve this issue.

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