The tachoencoders and the optotachos use the non-contact opto-electronic reading device of the incremental encoders.
The optical system provides immunity to electromagnetics interference and noise. The analogic output is obtained by conversion of the frequency into a proportional current or voltage.

The tachoencoders provide:
- the signals of an incremental encoder
- linear analogic signal depending on the rotation speed of the encoder

The optotachos provide analogue signal only.