How a Rotary Incremental Encoder Works. Direction and Position.

Summary

In this video, Tim explains how encoders track position, addressing common myths and misconceptions. Using a Micro 850 PLC trainer and an encoder simulator, Tim demonstrates the workings of quadrature encoders, focusing on the A and B signals, their 90-degree offset, and how these transitions determine direction and counts. The video dives into how these signals can be interpreted to track forward and reverse movement, using specific transitions of the A and B channels. The session concludes with the development of a ladder diagram program to track the encoder simulator, making the process clear and actionable.

Takeaways

• 😀 Encoders track position using signals that create a square wave pattern, with A and B signals offset by 90 degrees.
• 😀 A quadrature encoder uses four distinct transitions of the A and B signals to determine direction and count position.
• 😀 The Micro 850 PLC and its high-speed counter module are used to measure encoder outputs in this demonstration.
• 😀 A signal scope is connected to the encoder output to visualize and analyze the signals, revealing distinct square wave patterns.
• 😀 The encoder has 1024 steps per revolution, and the A and B signals generate quadrature transitions for forward and reverse directions.
• 😀 The A and B channels help determine whether the movement is forward or reverse, based on their on/off transitions.
• 😀 The key to direction determination lies in the transition of A and B signals; for example, when A turns on with B off, it indicates forward motion.
• 😀 Reverse direction is indicated when A turns on with B on, or when A turns off with B on.
• 😀 The four transitions in the A and B signals allow for counting in both directions (forward and reverse), which is essential for position tracking.
• 😀 The program in the video will use ladder logic to track and manage encoder signals, providing practical control over the encoder simulator.

Q & A

What is the main topic of the video?

The main topic of the video is how encoders track position, with a focus on clearing up myths and misconceptions about the process.

What equipment is being used in the video for the demonstration?

The video uses a Micro 850 PLC trainer, an encoder simulator, and an oscilloscope for the demonstration.

Why is an encoder simulator used instead of physically spinning an encoder?

An encoder simulator is used to avoid the need for manually spinning the encoder, making the demonstration more efficient.

How does the oscilloscope contribute to the demonstration?

The oscilloscope is used to display the A and B signals, which show how the encoder's position is tracked through the square wave patterns.

What are the A and B signals in relation to the encoder's operation?

The A and B signals are offset by 90 degrees and work together to create a square wave pattern that indicates the encoder's position and movement direction.

What does the term 'quadrature' refer to in the context of encoders?

'Quadrature' refers to the four distinct transitions that occur between the A and B signals, which allow the encoder to determine direction and count.

What is the significance of the A and B signal transitions?

The transitions of the A and B signals help determine the direction of movement (forward or reverse) and allow the encoder to count the steps based on these transitions.

How does the encoder determine the direction of movement?

The direction is determined by the specific pattern of transitions between the A and B signals. For example, when A turns on with B on, the movement is reverse, and when A turns on with B off, the movement is forward.

What role do the B signal transitions play in determining direction?

The B signal transitions, similar to the A signal, are used to determine direction. For example, if B goes from off to on with A off, the direction is reverse, and if B goes from off to on with A on, the direction is forward.

What will the final program in the video do?

The final program in the video will be a ladder diagram designed to track the encoder's position using the transitions of the A and B signals.