Abstract
In a distributed, object-oriented, hierarchical shop control system, there are many ways of organizing the interactions between supervisory controllers and subordinate controllers. Depending on what model of job control is used, objects will be allocated differently among the levels of control, and the interactions between controllers will vary considerably. This paper describes five models of job control that are equally functional, but use different paradigms for managing jobs. Although each is attempting to serve the same purpose in the same context, the five ways of viewing the system lead to distinct implementations that cannot interoperate. This demonstrates the importance of specifying the control model when designing an object-oriented manufacturing system.
Beamline operation using an industrial control system and distributed object-oriented hardware access
