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Rotary encoders are easy to underestimate. They are often just small devices attached to a motor shaft, yet an entire machine may depend on the signals they produce.
When an encoder works, nobody pays much attention. When it fails, the machine may lose its position, report the wrong speed, move in the wrong direction or refuse to complete its homing sequence. Suddenly, that little sensor becomes rather important.
The Udemy course Motion Control: Rotary Encoders explains how encoders work, how their signals are interpreted and how to select the right type for an industrial application. I believe it is a very good course for automation technicians and engineers who want more than a surface-level explanation of encoder feedback.
[Motion Control: Rotary Encoders]
What Does the Course Cover?
Created by LEARNACON Inc., the course currently contains 11 sections, 58 lectures and approximately 5 hours and 32 minutes of video. It has a 4.4 rating from more than 100 reviews and was last updated in September 2023.
The curriculum covers:
- Closed-loop motion control
- Linear and rotary encoders
- Incremental and absolute encoders
- Quadrature A and B signals
- Index or Z pulses
- Encoder output circuits
- Resolution, precision and accuracy
- Optical, magnetic and capacitive technologies
- Network and serial interfaces
- Encoder sizing and selection
- Diagnostics and maintenance
It is a surprisingly broad curriculum for one component category. Then again, encoders are not quite as simple as counting pulses and hoping for the best.
Incremental Encoder Signals
The course explains how incremental encoders generate pulse signals representing movement.
Students learn about quadrature encoders, where channels A and B are shifted by 90 degrees. By examining which signal changes first, a controller can determine the direction of rotation.
The lessons also cover the Z or index pulse, which appears once per revolution and can be used for homing, synchronisation and position referencing. Sin/Cos encoder signals are introduced as well.
Output Circuits and Wiring Compatibility
Not every incremental encoder produces the same type of electrical output.
The course compares:
- Open-collector outputs
- Push-pull or HTL outputs
- Differential line-driver or TTL outputs
Understanding this difference is essential when connecting an encoder to a PLC, counter module or motion controller. Selecting the wrong interface can result in unreliable signals—or no usable signal at all.
Differential outputs are also discussed in relation to noise immunity, something that becomes particularly important around motors, VFD cables and long encoder connections.
Absolute Encoders and Communication Interfaces
Absolute encoders provide a unique position value instead of only producing pulses as the shaft moves.
The course explains single-turn and multi-turn absolute encoders, Gray code and the practical differences between absolute and incremental feedback.
It also introduces several communication interfaces, including:
- SSI
- EnDat
- Hiperface
- BiSS
- EtherNet/IP
- PROFINET
- EtherCAT
You will not become an expert in every protocol from these lessons alone, but the overview helps make sense of modern encoder datasheets and product catalogues.
Resolution, Accuracy and Selection
A high pulse count does not automatically mean that an encoder is accurate enough for every application.
The course separates resolution, precision and accuracy while explaining terms such as pulses per revolution, counts per revolution and bit resolution. It also shows how encoder speed and pulse frequency must be considered together.
Selection lessons cover solid-shaft, hollow-shaft and ring encoders, as well as environmental ratings, mechanical mounting, network compatibility and maximum operating speed.
Who Is This Course For?
The course should suit:
- Automation and control engineers
- PLC programmers
- Industrial maintenance technicians
- Machine designers
- Mechatronics students
- Engineers working with motion systems
Basic knowledge of factory automation and control is recommended.
Are There Any Downsides?
This is mainly an encoder theory, selection and application course. It is not a complete motion-programming course and does not provide extensive PLC programming projects involving real encoder hardware.
The course was also last updated in 2023, so specifications for individual products and communication technologies should be checked against current manufacturer documentation.
Final Verdict
Motion Control: Rotary Encoders is a very good specialised course for understanding one of the most important feedback devices used in automation.
Its strongest feature is its depth. The course connects encoder construction, electrical signals, resolution, network interfaces and mechanical selection instead of treating them as unrelated subjects.
Check the current course price and availability here: