Interaction of Discrete and Continuous parts of aBatch Process

Through a study taking past Computer-Integrated Manufacturing (CIM) experiences, and the ISA 5] and NAMUR 7] references into account, we tried to see how far techniques developed in the eld of Discrete Manufacturing Systems (DMS) could be extended to Batch Chemical Processes 1]. As a result, a distributed hierarchical control system has been built. The proposed supervisory control system is composed of two main parts: a discrete-state system and a continuous-state system. The discrete aspect of the control system corresponds to a Discrete Event System (DES). The plant, i.e. the process to be controlled by the DES controller, is a continuous state system represented by continuous models such as algebraic or diierential equations. For these continuous models of the process to be consistent with the eeective process state, an Event-Generator (EG) has been introduced. The paper addresses the articulation between the two "worlds", the discrete and the continuous ones, which is based on the notion of event. This is illustrated through a problem of material transfer to and from a storage tank of a batch operated plant.