What’s Above a Master Recipe, work flows in MES systems?
” The ISA 88 standard provides a powerful model for effective operations and control at the Process Cell and Master Recipe level, but says nothing about the levels above. The ISA 95 standard provides activity models and data exchange models, but does not tie these into the ISA 88 model. This paper discusses how the new models in the ISA 95 updated standard, Work Segments and Work Definitions, can bridge the gap between the ISA 95 models and the ISA 88 models, providing an easy to understand and well integrated solution to the ISA 88 problem, what is above the master recipe. The paper proposes the use of Work Definitions to define the routing of batches between process cells, production lines, storage, and production units. It shows how each of the elements within a Work Definition are used to define product (or general work) specific instructions for an MES area level work flow engine. The paper proposes a natural progression and hierarchy of activities that relate the well defined ISA
