The DO output interface can be directly connected to a micro-controller IO port, if there is a block detection sensor, such as the speed of the motor encoder can detect.
DO modules can be connected to the relay, limit switch, and other functions, it can also with the active buzzer module, compose alarm.

Wiring specification:

1. VCC Connect the positive 3.3 5 v power supply
2. GND Connect power negative
3. DO TTL switch signal output
4. AO This module does not work