3 - Systems Theory

Abstract

This chapter summarizes system theory. A system is the collection of elements within a defined boundary, which are interconnected in a specific fashion, to perform a specific set of tasks. Systems can be divided into two broad types: business systems and control systems. The status, characteristics, and behavior of the elements of a control system at any moment in time depend on other elements of the system and the outside systems interfacing with the system. Limit cycle is an undesirable effect and is a direct result of non-linearity. It is necessary for control unit to employ I/O processing cards that can sample, filter, and characterize process signals, independent of the main CPU. Control theory relates the process to the PID controller output. The operator interface requires a teamwork design. The C&I system structure or configuration can be divided into four distinct levels of hierarchy: unit control level, LAN based operator station level, host level, and management computer level. The operating system is a software program whose function is the management and overall control of the computer. It performs the memory allocations, input/output distribution, job scheduling, and interrupt processing. The hardware variety affects two important aspects of C&I systems: spare parts control, cost, and maintenance. All C&I system specifications should adhere to ISO 9000 codes of practice, including development, revisions, modifications, testing, and documentation and the database should be thoroughly tested at various stages of development.