A process modeling language for large process control systems

A process modeling language (PML) has been developed which aids the analyst in modeling the processes of large process control systems. Because PML is based on a conceptual framework close to the customer´s view of controlled processes, a PML model is an effective communication medium between the analyst and the customer. PML allows a process to be decomposed into activities and a composite activity to be decomposed into more primitive activities. The structuring facility for these decompositions is the same. PML represents activity sequences by scenarios and uses conditions to control their start and end. The modeling of various operation sequences, interprocess sequence control, and operators´ interactions is made easy. The condition facility also facilitates the specification of various timing constraints. Therefore, PML is a valuable aid for the requirements analysis of large process control systems