Features PLC Connection: When connecting the PLC input, the COM terminal is connected to the 24V power supply, the input terminal is connected to the signal output S1‑S8 of the board, and the optocoupler GND is connected to the negative pole of the power supply. Volt Detection: Used to detect whether AC 220V exists, can also use MCU for testing, and the working voltage is 3‑5V. Level Output: When the 220V voltage is normal, it outputs a low level. When the 220V is powered off, it outputs a high level. Working Tips: The blue 5.0 terminal is connected to the 220V voltage, and the yellow pin is the signal output. Good Material: Adopting high quality PCB material, not easy to malfunction, very durable for long term use. Specification: Item Type: Optocoupler Isolation Board Material: PCB Function: Test whether AC 220V exists. Output TTL Level: MCU can be used for testing, the voltage is 3-5V. Connection: Output can be connected to PLC 24Vb.  Package List: 1 x Optocoupler Isolation Board Note: After the module is powered up, do not touch any part of the white wire frame on the board as it is high voltage. Pay attention to electrical safety. Package List 1 x Optocoupler Isolation Board