This paper explains the modelling of distributed discrete-event systems in one single simulation model. Our purpose was to evaluate the design of the distributed system and to highlight the communications required between the sub systems. This forms a contrast to the distributed simulation where the system is taken as a whole and the simulation tool makes transparent the communications between the various parts of the system. To illustrate our discussion, the paper also presents the simulation model of a unit for engines regulation coupled with its control system. We modelled it like a single model composed of seven independent models. To proceed, we used a discrete-event simulation language (Arena 8).