Two wire communication apparatus and method

A system including a controller for controlling and monitoring a base module and a plurality of remote equipment modules, the base module further comprising a power source capable of powering each remote equipment module, the equipment environment further includes a first electrical wire and a second electrical wire forming a two wire bus wherein said base module and each said remote equipment module are electrically attached to said two wire bus, the controller comprising:

• a switch means capable of being either off or on, wherein when on, full power is applied to the first and second electrical wires, wherein when off, power on the first and second electrical wire is current limited, thereby allowing bidirectional low power data transfer along said two wire bus,
• wherein each remote equipment module receives operating power from said base module over the two wire bus only when switch means is on,
• wherein said controller is enabled to transfer data between said base module and each said remote equipment module on said first and second electrical wires when said first and second electrical wires are current limited, using a low power communications protocol the communications protocol deploys a two wire communications cycle, the communication cycle further comprises:
• a first phase, the first phase is a full power cycle phase wherein the current is limited and the base module initiates a command,
• a second phase, the second phase is a communications phase, wherein current is limited and the base module initiates a command that is transmitted on the first and second electrical wire to at least one interface, thereby delivering said command to at least one of said remote equipment modules,
• a third phase, the third phase is a full power phase wherein the command is executed by the device,
• a fourth phase, the fourth phase is a response phase wherein current is limited and the equipment module responds to the command, the response is transmitted to the base module on the first and second electrical wires.