Encoder

Encoder is a instrument which detects device movement and converts it into analog or digital electrical signal. There are many different types of encoders which can detect different types of movement. Most prevalent difference between them is how they are presenting that position change, and which type of position change they can detect. That is why encoders can be listed into two groups. When it comes to change of position value there are two groups: absolute and incremental encoders. Second difference is the way position is measured and that is: linear and rotary. Encoder we had at our disposal during bachelor thesis is the incremental rotary encoder from SCANCON Industrial encoders.

Figure 6: 2RMHF rotary encoder

Rotary incremental encoders are meant to detect rotary motion and then report it back to the user by incrementing its value. Rotary motion usually of a motor shaft is converted to analog or digital signal and reported back to the user. Important to note is that rotary incremental encoders do not report absolute position, instead they show the change in position that has happened compared to the reference point. It achieves this task by utilizing two signals, A and B. When position is changed encoder sends two square shaped signals which increment the position value according to change. Faze difference between those two signals determines in which direction value is going to be incremented towards. That way it is possible to know which direction encoder is spinning.