“This shield enables you to interface many different devices to Arduino Nano using optically isolated inputs/outputs. The circuit consists of 4 Input channels and 4 Output channels and all 8 I/O lines are optically isolated. This project can help in various industrial applications where EMI noise and high voltage lines can damage the Arduino Nano or other circuits connected to it. Circuit is built using 8 x 6N137 optocoupler. The 6N137 optocoupler can switch at frequency up to 10 MHz.”