Communication system and method utilizing message frames having multiple thresholds for a multi-device vehicle occupant protection system

The present invention is generally directed to a communication system and method of a vehicle occupant protection system. Specifically, the present invention is directed to communication within a distributed protection system. A communication system () includes a communication bus () through which a power/voltage transmitter () conveys electrical energy and messages to a plurality of units (). The power/voltage transmitter () includes components for adjusting voltage of the electrical energy past a first predetermined threshold to provide a first type message frame and modulating the voltage of the electrical energy during the first type message frame to convey a first type message. The power/voltage transmitter () also includes components for adjusting the voltage past a second predetermined threshold to provide a second type message frame and modulating the voltage of the electrical energy during the second type message frame to convey a second type message.