A Mechanized Formal Refinement Proof of Modbus Communication Using Event-B Proof System

Abstract

Formal methods have been applied in the design of a great number of systems. Many protocols have been specified and verified formally. Some protocol standards are even defined by means of a formal method. This paper studies a based formal approach for testing associated properties of Modbus communication protocol with the Event-B Method. Event-B is a formal method for systems modeling, founded on set theory and predicate logic. It has the benefit of mechanized proof, and it is practicable to model a system in various levels of abstraction using refinement. Our aims are constructing a model with a clear and accurate formulation of the protocol properties and discharge all proof obligations. To satisfy these, attentive choice of invariants and machine theorems was important and eased the proof effort. A major focus of our work has been to explore the use of the Event-B method for formally specifying Modbus protocol. The supported language was sufficiently expressive and all proof obligations could be discharged. We reached a good degree of automatic proof. All interactive proofs involved a small number of steps and were straightforward to reach. The result of this approach was that we achieved a very high degree of automatic proof.