The design and implementation of an object-oriented process control loop framework

Control loop is an essential part of the process control system that must control physical processes in which it is difficult or impossible to compute correct output value with input values alone. In this paper, we describe the design and implementation of a highly reusable object-oriented control loop framework to support the efficient development of real time process control applications. The basic building block in our control loop framework is the Point class. The Point class encapsulates process variables of a control loop together with control algorithms so that it can be easily adapted and extended to process control applications that have various structures and behaviors. The core of this paper is the design pattern of event/time-triggered Point class that can be used for flexible implementation of monitor and control functions required of target processes through the interaction of point objects performing continuous re-computation.