How to Connect a 3-Wire DC Sensor to a PLC Check out the full blog post over at https://realpars.com/discrete-sensors-part-2/ To connect a “three-wire” discrete DC device to the PLC, we will need to identify whether the device is an NPN or a PNP type. The NPN switches are referred to as “sinking”, and PNP switches are referred to as “sourcing”. These sensors have three wires. Wire 3 (black wire) is always connected to the load, which is the terminal for input on a PLC digital input card. #Automa