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Diploma thesis

Offline Debugging for Continuous Function Charts

(Original Title:Offline-Debugging für Continuous Function Charts)



PLC programming is the most important step in PLC system. In the early age, the programming was performed directly in PLC. With the developing of computer technology, PLC programming tasks, such as program construction, modification and compilation, are done with the help of separate software. PLC program may not achieve the required functions, so there is a need for providing debugging functions in such a tool to efficiently locate and correct faults in PLC program, especially when the program is very large and complex, which makes the bugs more invisible.
This thesis concerns with the design and implementation of such an offline debug component in an existing PLC system called CFC system. In this document, the whole steps for the component development are discussed. It starts with the requirement analysis. Then the design and implementation are described in details. The debug functions in the system are evaluated by each testing case. A LED flashing program with faults is used as an example to show how to detect the faults by step-by-step debugging. Finally, ideas for future work are presented for the improvement of debugging system.

Author: Weifei Tao

Tutor: Dipl.-Inf. Johannes Drexler

In Cooperation with: Siemens PTD Energy Automation