Application of graphical specification methodologies to manufacturing control logic development: a classification and comparison

Robust formal specification of control logic is vital for efficient developmentof discrete-event control software for real-time manufacturing systems.This paper classifies real-time control specification methodologies into three types based on their levels of abstraction. Representative methodologies in each class are briefly introduced, including a new methodology called discrete-event control networks (DECN). An example of a manufacturing discrete-event control system is presented and the logic is developed under each of the methodologies for comparison. The desirable characteristics and functions of real-time manufacturing systems specifications are identified. The paper then discusses the relative abilities of the representative methodologies to address these characteristics.