The output terminal is wired to one side of the circuit. The other side is ground or L2. Multiple L2 terminals are provided for convenience. Sensors are connected to input terminals. When a output terminal is energized by the computer, there will be a red LED glowing.
White modules are inputs from flowmeters and other sensors.
A sensor is wired from L2 to the sensor and from the other side of the sensor switch to the input terminal. When contacts are closed, there will be a red LED glowing. Communications Communications is normally via 2 pair RS-485 cable. Satellite boxes may be placed up to 5000 feet from the central computer with cable. Radios may also be used for communication.