Rotary switches can be used to replace the traditional resistance potentiometer analog function rotary pulse generator. These rotary switches are usually used in the front panel of the instrument and the man-machine interface of the audio-visual control panel. The rotary switches use orthogonal optical encoder as the pure digital device to replace the analog potentiometer. These rotary switches are similar in appearance to the traditional or resistance potentiometer, but these rotary switches the internal structure of the switch is completely digitized and uses optical technology. Similar to the traditional incremental encoder products, it has two orthogonal output signals (channel A and channel B), which can be directly connected with the encoder processing chip.