State Diagrams: A New Visual Language For Programmable Logic Controllers

Abstract

<p>Ladder Logic has been the dominant defacto method for programming programmable logic controllers for over 30 years. Primarily designed as a replacement for electronic relay boxes Ladder Logic uses the analogies of circuits and wires. With the changes in education and training Ladder Logic has not kept up with the times. Ladder Logic is difficult to understand for a software background trained operators. In addition with increasingly difficult control logic strategies, Ladder Logic has become cumbersome and difficult to use.</p> <p>This thesis seeks to examine a different approach to visual programming that is more suitable to modern software trained individuals. A visual programming language will be established based on finite state machines. We then define both the syntax and semantics of our visual language, demonstrate the correctness of operation and execution. This thesis also defines a reference hardware platform and shows our graphical tool used to construct programs in this new language.</p> <p>The major contributions of this thesis include the development of a prototype programming language, a graphical integrated development environment tool, and a prototype hardware environment.</p>