Description: This is a Speed Measuring Sensor Module for Arduino. It also can be with an active buzzer module and compose an alarm. It explains how slot-type optocouplers work, how this module converts mechanical motion into clean digital pulses, how to calculate speed and RPM correctly, and how to. Widely used in motor speed detection, pulse count, the position limit, etc. DO modules can be connected to the relay, limit. Introducing the Slot Type Optical Coupling Module, a highly versatile component designed to elevate your Arduino projects with its advanced functionality. The output status indicator lamp output high, output low lights.