Application of state-event-action logic for controlling complex industrial systems

Traditionally, flow charts have been used to describe industrial control systems. Flow charts provide a nice step-by-step orderliness to complex systems; but unfortunately, real systems do not operate step-by-step, they operate concurrently. In real systems there will be many actions happening simultaneously. Trying to use flow charts to describe concurrent systems becomes a difficult and complex task. Trying to write programs from such flow charts is even more of a chore, and such programs will not usually run efficiently. Nowadays, there is a lot of talk about describing complex industrial systems as "state-action machines." Using state-action machines is a big step in the right direction, but many programmers continue to try to use flow chart techniques to describe state-action machines. This practice leads to diagrams that are in some cases more complex than traditional flow charts. This paper describes a way to create complex control systems as interacting sets of state-event-action (SEA) modules. The SEA method involves dividing any machine, assembly line, or process into distinct modules. Each module progresses through its own particular set of states, and responds with specific actions to external and internal events according to its state.