6,902 research outputs found

    LLM4PLC: Harnessing Large Language Models for Verifiable Programming of PLCs in Industrial Control Systems

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    Although Large Language Models (LLMs) have established pre-dominance in automated code generation, they are not devoid of shortcomings. The pertinent issues primarily relate to the absence of execution guarantees for generated code, a lack of explainability, and suboptimal support for essential but niche programming languages. State-of-the-art LLMs such as GPT-4 and LLaMa2 fail to produce valid programs for Industrial Control Systems (ICS) operated by Programmable Logic Controllers (PLCs). We propose LLM4PLC, a user-guided iterative pipeline leveraging user feedback and external verification tools including grammar checkers, compilers and SMV verifiers to guide the LLM's generation. We further enhance the generation potential of LLM by employing Prompt Engineering and model fine-tuning through the creation and usage of LoRAs. We validate this system using a FischerTechnik Manufacturing TestBed (MFTB), illustrating how LLMs can evolve from generating structurally flawed code to producing verifiably correct programs for industrial applications. We run a complete test suite on GPT-3.5, GPT-4, Code Llama-7B, a fine-tuned Code Llama-7B model, Code Llama-34B, and a fine-tuned Code Llama-34B model. The proposed pipeline improved the generation success rate from 47% to 72%, and the Survey-of-Experts code quality from 2.25/10 to 7.75/10. To promote open research, we share the complete experimental setup, the LLM Fine-Tuning Weights, and the video demonstrations of the different programs on our dedicated webpage.Comment: 12 pages; 8 figures; Appearing in the 46th International Conference on Software Engineering: Software Engineering in Practice; for demo website, see https://sites.google.com/uci.edu/llm4plc/hom

    Practice of Industrial Control Logic Programming using Library Components

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    This chapter discusses Programmable Logic Controller (PLC) programming practice, particularly the use of library components, in the automotive industry. A study of program structure and use of library components at two European car manufacturers is presented. The main purpose of the study is to provide understanding of current PLC programming in industry

    Modeling and Analysis of Stage Machinery Control Systems by Timed Colored Petri Nets

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    International audienceThis paper presents an approach and successful experience of applying timed colored Petri nets on modeling and analyzing a stage machinery control system. The programmable logic controllers (PLCs) based system is modeled with timing constraints. The compositionality is incorporated in the modeling process of the entire design. The PLC synchronization problem with the interactions of environment is analyzed by the state space analysis method. The case studies demonstrate the effectiveness of the approach
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