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SUPPORT SOFTWARE FOR THE DEVELOPMENT OF programmable logic-CONTROLLER APPLICATIONS

REAL-TIME SYSTEMS 1995年第2期9卷 173-193页

作者： HASSAPIS, G PAPADOPOULOS, J Division of Electronics and Computer Engineering Department of Electrical Engineering Aristotle University Thessaloniki Greece

Enhancements to the sofware aids, used for the development of programmable logic Controller programs, are proposed in this work. A possible architecture of the software realizing these enhancements and the language constructs required for its configuration to a specific application are also presented. Based on this architecture, experimental software aids have been developed to demonstrate that it is quite feasible to provide the major services considered in this proposal. These services allow the program developer to emulate the dynamic operation of a specific programmable controller to alternative scenarios of input variations and relationships over a defined time horizon, and configure displays of graphics and timing diagrams which may assist him in following up and testing the program execution.

关键词： programmable logic controllers REAL-TIME SYSTEMS SEQUENTIAL CONTROL INDUSTRIAL CONTROL

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ICA - EVOLUTION IS BETTER THAN REVOLUTION

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WATER SCIENCE AND TECHNOLOGY 1989年第1-11期21卷 1325-1331页

作者： COMLEY, AR United Kingdom

This paper describes how the impact of I.C.A. can cause considerable difficulties to the unknowledgeable user. It is proposed that a programme of gradual evolution is devised to improve understanding and confidence in new *** are given on developing expertise, the specification and selection of equipment, installation and commissioning and overcoming operational problems.

关键词： Instruments Control Automation programmable logic controllers Maintenance

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Industrial hydraulics and electronics converge for synergy

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CONTROL ENGINEERING 1996年第7期43卷 71-74页

作者： Phillips, F Vickers Inc Rochester Hills United States

Hydraulics is respected as a highly responsive and robust control technology, with a tolerance for extremely hostile environments. Recent product developments are leading to opportunities for even broader application of fluid power. The industry's latest developments are significantly influenced by several factors. Among these are energy efficiency, ease of use, and global standards compliance and support.

关键词： machine control hydraulics fluid power position control proportional and servo valves programmable logic controllers

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ELEGANT: Security of Critical Infrastructures With Digital Twins

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IEEE ACCESS 2021年 9卷 107574-107588页

作者： Sousa, Bruno Arieiro, Miguel Pereira, Vasco Correia, Joao Lourenco, Nuno Cruz, Tiago Univ Coimbra CISUC DEI Polo Pinhal Marroco 2 P-303290 Coimbra Portugal

The past years have witnessed an increasing interest and concern regarding the development of security monitoring and management mechanisms for Critical Infrastructures, due to their vital role in ensuring the availability of many essential services. This task is not easy due to the specific characteristics of such systems, and the natural resistance of Critical Infrastructures operators against actions implying downtime. Digital Twins, as accurate virtual models of physical objects or processes, can provide a faithful environment for security analysis or evaluation of potential mitigation strategies to be deployed in face of specific situations. Nonetheless, their on-premises deployment can be expensive, implying a significant CAPEX whose return will depend on the ability to plan and deploy a suitable support infrastructure, as well as implementing efficient and scalable data collection and processing mechanisms capable of taking advantage of the acquired resources. This paper presents an off-premises approach to design and deploy Digital Twins to secure critical infrastructures, developed in the scope of the ELEGANT project. Such Digital Twins are built using real-time, high fidelity replicas of Programming logic controllers, coupled with scalable and efficient data collection processes, supporting the development and validation of Machine Learning models to mitigate security threats like Denial of Service attacks. The validation approach of ELEGANT, which leveraged from the capabilities of the Fed4Fire federated testbeds evaluated the feasibility of using cloudified Digital Twins, thus converting a significant part of the projected CAPEX for the in-premises model into on-demand, pay-as-you-go OPEX, eventually paving the way for the establishment of a DTaaS (Digital Twin as a Service) paradigm. The achieved results demonstrate that the data pipelines providing support for the ELEGANT Digital Twins have low impact in terms of resource usage in Denial of Service and

关键词： Security Digital twin Monitoring Integrated circuits Process control SCADA systems Analytical models Digital Twins SCADA pipelines security programmable logic controllers DTaaS

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Introducing X-machine models to verify PLC ladder diagrams

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COMPUTERS IN INDUSTRY 2001年第3期45卷 277-290页

作者： Chambers, C Holcombe, M Barnard, J Hlth & Safety Lab Sheffield S3 7HQ S Yorkshire England Univ Sheffield Dept Comp Sci Sheffield S10 2TN S Yorkshire England

Ladder diagram is a ubiquitous PLC programming language often used in safety-related control and protection systems. The design and analysis of ladder diagram programs by engineers is often ad hoc using a variety of techniques that may be applied with varying levels of rigour. This paper introduces X-machines, a state-based formalism, to consistently model and verify PLC ladder diagrams. X-machines model control and data flow unambiguously, and have associated with them a test set generation method that is amenable to automation. This work shows by an example, namely an oil tank warning system, how ladder diagram programs, can be successfully modelled using variants of the X-machine model. Crown Copyright (C) 2001 Published by Elsevier Science B.V. All rights reserved.

关键词： programmable logic controllers X-machines testing ladder diagram

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Compositional Verification of PLC Software using Horn Clauses and Mode Abstraction

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IFAC-PapersOnLine 2018年第7期51卷 428-433页

作者： Bohlender, Dimitri Kowalewski, Stefan Embedded Software RWTH Aachen University Aachen Germany

Real-world PLC software is modular and composed of many different function blocks. Due to its cyclic execution, an engineer's mental model of a single function block often exhibits state machine semantics – partitioning a block's behaviours into different modes of operation. We propose a technique called mode abstraction for automatic computation of such high-level models from program semantics and investigate its impact on the overall model checking performance. To this end, we use constrained horn clauses to characterise the program semantics, mode transitions and safety goals in a compositional way. The resulting verification conditions are discharged using an SMT solver. Evaluation of our prototypical implementation on examples from the PLCopen Safety library shows the effectiveness of both the chosen formalism and mode abstraction. © 2018

关键词： Model checking Abstracting Accident prevention Computer aided software engineering Computer software selection and evaluation Formal verification logic programming programmable logic controllers Semantics Automatic computations Compositional verification High level models Industry automation Modes of operation Prototypical implementation Software safety Verification condition

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Application of an adaptive model predictive control algorithm on the Pelton turbine governor control

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IET RENEWABLE POWER GENERATION 2020年第10期14卷 1720-1727页

作者： Beus, Mateo Pandzic, Hrvoje Univ Zagreb Fac Elect Engn & Comp Dept Energy & Power Syst Unska 3 Zagreb Croatia

Traditionally, hydro turbine governor applications mainly rely on classical proportional-integral-derivative controllers. A classical controller can perform optimally only at the operating point chosen during the controller design. Since hydro power plants are highly non-linear systems alternative control approaches based on adaptive parameters are needed. Historically, due to the limited computation capabilities of microprocessors and programmable logic controllers (PLCs) used in hydro turbine governors, adaptive control schemes were not frequently applied. However, the latest generation of microprocessors and PLCs facilitate the application of adaptive control scheme based on predictive control algorithm for plants with faster dynamic behaviour. In that regard, this study introduces an adaptive controller based on model predictive control (MPC) algorithm developed and applied to a non-linear simulation model of a laboratory hydro power plant. The applied MPC algorithm is based on a linear prediction model whose parameters are identified offline for different operating points across the plant's operating range. The adaptive control scheme updates the prediction model parameters depending on the current operating point. Furthermore, the predictive control algorithm applied in this study is set up as a quadratic programming (QP) optimisation problem that is solved online using a QP solver in a form of Hildreth's algorithm.

关键词： hydraulic turbines linear systems fuzzy control adaptive control power generation control robust control control system synthesis predictive control three-term control quadratic programming nonlinear control systems adaptive model predictive control algorithm Pelton turbine governor control hydroturbine governor applications linear plant model fixed parameter scheme controller design hydropower plants nonlinear systems alternative control approaches adaptive parameters programmable logic controllers hydroturbine governors nonlinear simulation model laboratory hydropower plant MPC algorithm linear prediction model whose parameters adaptive control scheme updates prediction model parameters classical proportional-integral-derivative controllers quadratic programming optimisation QP solver Hildreth's algorithm QP optimisation

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PLC validation during project implementation

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MEASUREMENT & CONTROL 1998年第1期31卷 10-13页

作者： Mitchell, R Roscoe, S Pfizer Ltd Sandwich Kent England

In the paper the validation of programmable logic controllers (PLC) for using in pharmaceutical industry is reviewed. It is shown that the validation is an integral part of the implementation of a PLC application and it is a prerequisite for any project in the pharmaceutical industry. The installation qualification, operational qualification and performance qualification for PLC are discussed.

关键词： programmable logic controllers

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Distributed PLC Based on Multicore CPUs - Architecture and Programming

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IFAC-PapersOnLine 2016年第25期49卷 1-7页

作者： Milik, Adam Hrynkiewicz, Edward Institute of Electronics Silesian University of Technology of Gliwice Poland

The paper presents a complete approach to distributed control system design including architecture and programming. The system consists of distributed controllers connected with a network. A multiple core controller architecture is proposed utilizing independent bit and word units in MIMD structure. Calculation process is efficiently synchronized by original implementation of semaphored memory system. The program partitioning and distribution among processing units is made automatically by proposed compiler. For a purpose of program distribution and scheduling a graph based representation of the standard program is used. Developed conversion model enables compilation of selected standard languages into independent graph based form. The distributed controller architecture has been prototyped with use of PFGA devices that enables specific implementation and evaluation of performance. The data exchange was implemented with use of deterministic protocol based on token passing. © 2016

关键词： Distributed computer systems Closed loop control systems Computer architecture controllers Distributed parameter control systems Electronic data interchange Field programmable gate arrays (FPGA) Graphic methods Multicore programming Network architecture Program compilers programmable logic controllers compiler Control network Controller architectures Deterministic protocols Distributed controller Distributed systems Graph based representations MIMD

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The PLC: a logical development

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MEASUREMENT & CONTROL 2010年第9期43卷 280-284页

作者： Walker, Mark Bissell, Chris Monk, John Open Univ London England

programmable logic controllers (PLCs) have been used to control industrial processes and equipment for over 40 years, having their first commercially recognised application in 1969. Since then there have been enormous changes in the design and application of PLCs, yet developments were evolutionary rather than radical. The flexibility of the PLC does not confine it to industrial use and it has been used for disparate non-industrial control application. This article reviews the history, development and industrial applications of the PLC. The 1960s was a decade of intense technological development influenced by the political circumstances of the time;it was the height of the Cold War and the space-race and in the United Kingdom, Prime Minister Harold Wilson emphasised the role of technology in his famous "White Heat" speech. Sir Leon Bagrit, a leading industrialist, became chairman of Elliot Automation, a newly established company. Bagrit's BBC Reith lectures of 1964 on automation, encapsulated the industrial and technical ambitions of the time. Automation was a hot topic and transistor electronics and computers were unfolding as significant technologies.

关键词： programmable logic controllers

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