Organization of industrial control computers

Rodd, Michael Godfrey

Organization of industrial control computers

Doctoral Thesis

1976

Publisher

University of Cape Town

Department

Department of Electrical Engineering

Faculty

Faculty of Engineering and the Built Environment

Abstract

The efficient use of industrial control computers is recognized as an organizational problem akin to the traffic-switching problem in communications. A systematic approach to this problem is proposed, based on theory developed for the handling of telephone traffic. The application of the approach indicates that it is necessary to re-evaluate traditional hardware/software relationships. A change in these relationships is desirable, since multi-programmed computers spend too much time in handling their own organization. This situation is compounded in time-critical industrial process-control applications. It is proposed that the solution lies in the use of a flexible hardware operating system, working in close relationship with a conventional minicomputer. The unit proposed to implement this function, termed a microcontroller, makes use of the new bipolar microprocessor elements and provides a high-speed, flexible control unit, adaptable to user requirements. To retain a high degree of flexibility the microcontroller is microprogrammable. In essence, the unit executes the principal functions of a real-time operating system, acts as a pre-processor for all incoming requests, and ensures a high rate of task-switching. This system is applied to a series of configurations, each selected to demonstrate, quantitatively, the value of the technique in real applications. Comparisons are made between real-time control configurations based on the software-implemented approach and the identical configurations based on this system. The proposed strategy is shown to result in a better and more economical industrial controller. The wider implication for any aspect of organization is that "bigger" is not necessarily "better". Successful management implies effective use of facilities, rather than a proliferating structure.