These protocols exploit the directionality of signal propagation and enforce time constraints to achieve collision-freedom. A correct implementation of such a protocol requires a careful analysis of time-dependent interactions of event occurrences using a formal method. We present a model for broadcast bus networks. The novel features of our model include the ability to specify broadcast channels and the specification of real-time behavior. The broadcast characteristics of cables or buses are captured by some simple axioms.
Real time is modeled as a discrete quantity using clocks and time variables.
Real-time properties are specified by safety assertions. To illustrate our model and analysis method, we present a specification of the Expressnet protocol. We found that to achieve collision-freedom, a small modification to the original Expressnet protocol is needed. Verification The Digital Library is published by the Association for Computing Machinery.