Object-Oriented Ladder Logic Development Framework Based on the Unified Modeling Language

Abstract

In order to improve current PLC programming practices, this paper proposes an object-oriented (O-O) ladder logic development framework in which ladder code is generated automatically based on the O-O design results and can be verified by port-level simulation. Proposed ladder logic development framework consists of two phases: First is the design phase. Second is the generation and verification phase. During the first phase, O-O design model is built, which consists of three models: functional model, structure model and interaction model. Two steps are conducted during the second phase. Firstly, ladder code is generated automatically using the interaction model of design phase. Secondly, generated ladder code is verified by input/output port simulation. In order to show the applicability of proposed framework, a software tool for the design and generation of ladder code is also developed.