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The increased complexity of new adaptive passenger restraint systems requires the implementation of a serial communication network, which connects the squibs and sensors to a central electronic module. The requirements on such a safety-critical backbone include the tolerance to serious damage of the bus wires, which may occur also during the event of a crash. This paper describes the concept of an in-vehicle network, which combines economy, robustness and reliability with the exacting performance of high-speed multi-master communication. It needs only two wires for the distribution of power, data and clock in the system. The network offers real-time fault tolerance to all kind of wiring failures, which makes this system superior to all other concepts proposed for this application.

An electronic module in a J1939-compatible network requires to be equipped with a CAN protocol controller, which might be integrated on the main CPU or is attached to the CPU as a separate chip. Besides the fundamental functions required to transmit and receive CAN-compatible messages, the CAN hardware can support the CPU effectively, if the typical communication structure of J1939 was respected during the design of the CAN controller. It is shown that the CPU's management of, especially, received messages can be accelerated, if the CAN controller's architecture reflects the internal structure of the J1939 recommendations.