A Basic Guide: How Feedback Encoder Devices Operate

Feedback is used in closed loop systems in applications all over the world to control speed and/or position, and it has an important role in keeping equipment operating smoothly and accurately. Feedback is available in a variety of devices as well as models. It is important to understand how feedback operates, so the best benefits can be used in the application.


Many applications operate open loop and many operate closed loop. In an open loop system, the operation can become uncontrolled; in a closed loop system the process is controlled. The difference is feedback.

in a closed loop system feedback signal is sent back to the control, to relay if the operation was successful

An open loop system is a process in which the signal travels from the control to the motor. An example of an open loop system is as follows: a motor is used in a bin sorting application, and everything proceeds as expected as long as the motor can pick and place parts in the proper bin. However if for some reason the mechanism jams and the motor can’t move, the control is not aware of the situation and will continue sending commands that are essentially ignored, so the parts do not get sorted.

In a closed loop system the signal travels from the control to the motor, as above, however the difference is that there is another signal, a feedback signal, which returns to the control, thus informing the control the operation was successfully. If the feedback informs the control that the operation was not successful, then the control could alert an operator that the process was not completed correctly. Closed loop systems use feedback for speed/position information and process control in many applications.  

There are a variety of devices available in the marketplaces which are employed to derived information about the application’s speed and/or position thus controlling and guaranteeing that the process occurs correctly. These include: tachometer, Hall sensors, encoder, and resolver.

Click the button below to read the complete guide, and view a basic chart on various feedback devices and their advantages and various characteristics.

preview of white paper about encoders and feedback devices