This paper is devoted to the presentation of the main lines of an unified functional formalism for modelling complex industrial systems, that is to say systems that typically mix a big number of different software and physical devices. Our approach is based on a discrete non-standard representation of time. It captures both the hierarchical architecture and the temporal and data multi-scale structures of a complex industrial system. We show in particular in this paper how our formalism allows to recover in an totally unified way various sorts of simple systems such as Turing machines, elementary conservative physical systems and low level software/physical interfaces (sampler, modulator).