Software PIC Design On Linux Operating System: Integrated Logic Controllers

The programmable logic controller (PLC) has been used in automation for more than40years, yet these controllers are not interoperable. Vendors are seeking for integration, reuse,flexibility and optimization to adapt to a rapidly changing and competitive market.Standardization is a key to achieve integration and reuse in this type of applications. Withoutstandardization there can never be harmonization. The direction towards internationalstandardization led to the definition of the IEC61131standard of which Part3defines asoftware model for defining automation projects as well as5programming languages.However, there is still no true reusability and interoperability among programming tools.This thesis analyses the PLC Integrated Development Environment (IDE) and proposes anovel approach to achieve interoperability of PLCs through file architecture specification ofLadder Diagram program and Ladder Diagram elements. The thesis shows the variousinterfaces to be supported by the files. We show that there are3interfaces to be satisfied bythe Ladder Diagram Program File:(1) Graphical User Interface;(2) Input/output Interface;(3) Interface to other Programming languages. Similarly there are3interfaces to be satisfiedfor a function block:(1) Graphical User Interface;(2) Input output Interface (3) Interface toother Programming languages. The architecture shows that the interface to otherprogramming languages is the file specification itself. When we have a standardized filespecification, we have interface to other programming languages but we won’t achieveinteroperability until we have the other two interfaces also satisfied. If these interfaces aresatisfied by the file specification then we have interoperability and therefore we haveintegrated PLCs.We further discuss the IDE in terms of the Compiler and the Graphical user interface. Inthis research we developed algorithms for the compiler between Ladder Diagram andInstruction list. The algorithms brought us to graphical manipulations which are useful toachieve integration on graphical user interface. We further showed that auxiliary variables canbe eliminated in the IEC61131-3IL program by adding two instructions to the instruction setto handle a second data stack.