Noise and signal considerations for encoders in motion control applications

A new white paper from British Encoder Products (BEPC) focuses on strategies and ways to reduce noise and signal distortions to ensure the signal from your encoder remains clean and uncorrupted.

An encoder is an electro-mechanical transducer that converts mechanical rotary motion into digital signals for the control of machinery. The encoder produces a square wave signal as the shaft rotates.

Speed, position, servo feedback, etc, can be determined through proper processing of this signal. As the electrical signal leaves the encoder, it is ‘clean’ of electrical noise. However, by the time the signal reaches its intended counter, PLC, etc, it may be degraded and may not be ‘clean’ enough for the system to work properly.

To ensure clarity of signal from your encoder, and avoid excessive electrical noise, there are several options and installation considerations to think about. Electrical noise must be mitigated, and there are several strategies to do that. The encoders’ cables are another important consideration, with cable length, termination and connections all playing a part in keeping a signal ‘clean’.

There are several methods that can reduce noise in an encoder’s electrical signal:

1. Route power and signal lines separately
2. Twist and shield signal lines, and place signal lines at least 12 inches from other signal lines and from power leads
3. Maintain signal wire continuity from the encoder to the controller/counter (ie, avoid junctions or splices)
4. Provide clean regulated power to encoder and associated equipment (± 2%)
5. Ensure equipment (motors, drives, shafts, etc) is properly grounded
6. Connect encoder cable shield to ground at controller/counter end, leaving the end near the encoder disconnected.

You can read the white paper here on noise and signal considerations for encoders in motion control applications. And for expert advice, the engineers at BEPC are on hand to tackle the toughest encoder questions, providing the right answers that make sense for your application.

BEPC encoders increasingly becoming the basic elements of automation systems in industries as machine building, robotics, automation and sorting, aerospace, food and beverage, printing, materials handling, automated guided vehicles and more.