Welcome to our shop! This Opto Isolator Module is designed to detect the existence of 220V AC power and provide stable high and low levels (NPN output). It can be easily connected to a microcontroller or a PLC. To detect the output TTL level, you can connect the module to a microcontroller with a power supply of 3-5V. It can also be connected to a PLC with a 24V level. When connecting to the PLC input terminal, make sure to connect the COM terminal of the PLC to the 24V input terminal of the power supply. Then, connect the signal output OUT of the board to the PLC input terminal. Finally, connect the GND on the optocoupler board to the negative pole of the power supply. This module comes with a 2P and 3P terminal. The green 2P 5.0 terminal is used to connect to a 220V voltage source, while the 3P terminal is used to connect to the input of the microcontroller. The module also features an LED light indicator. When there is a 220V input, the LED will be on, indicating that the optocoupler is turned on and the output is low. On the other hand, when there is no 220V input, the LED will be off and the optocoupler will not be connected. In this case, the output is pulled high by the resistor. 100% Satisfaction: Our customers are our top priority. If you find any product problems after receiving the goods, such as damage and incorrect quantity of goods, please contact the seller immediately. We try our best to provide you with satisfactory after-sales service. Thank you for choosing our Opto Isolator Module!