Formal methods provide techniques and tools for constructing models of software systems and more generally of hardware/software systems. Mathematical models are incrementally developed and provide informations validated by proof assistant; the development starts by a simple model and the process enriches current models by adding details from the requirements; the process leads to a sequence of models related by the refinement relation and a sequence of directed acyclic graphs stating dependency among parameters to be computed by the future monitoring tool. Those DAGs together with the events of models, can be used to generate an architecture of the final system and a code for computing each parameter. The resulting architecture and the resulting code are produced from formally validated components; moreover, DAGs help in the organization of computations among parameters. Our work shows how formal models and DAGs can be used to build a system on chip using SystemC.