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MODELING programmable logic controllers FOR logic VERIFICATION

IEEE CONTROL SYSTEMS MAGAZINE 1994年第2期14卷 53-59页

作者： MOON, I Dept. of Chem. Eng. Yonsei Univ. Seoul

Verification method has been developed for determining the safety and operability of programmable logic controller (PLC) based systems. The method automatically checks sequential logic embedded in PLCs and provides counterexamples if it finds errors. The method consists of a system model, assertions, and a model checker. The model is a Boolean-based representation of a PLC's behavior. Assertions are questions about the behavior of the system, expressed in temporal logic. The model checker generates a state space based on the above two inputs, searches the space efficiently, determines the consistency of the model and assertions, and supplies counterexamples. A modeling technique has been developed to verify relay ladder logic (RLL), a PLC programming language. The performance of the model checker is studied in a series of alarm designs

关键词： Boolean based representation Boolean functions PLC programming language alarm designs alarm systems assertions logic testing logic verification model checker modeling operability programmable controllers programmable logic controllers relay ladder logic safety sequential circuits sequential logic state space system model temporal logic

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Simulated false data injections attacks on emulated and hardware programmable logic controllers of the pressurizer in a representative pressurized water reactor plant

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Journal of Cyber Security Technology 2022年第4期6卷 216-241页

作者： El-Genk, Mohamed S. Schriener, Timothy Institute for Space and Nuclear Power Studies and Nuclear Engineering the University of New Mexico AlbuquerqueNM United States

Manipulating sensors data and/or programmable logic controllers (PLCs) in Instrumentation and Control (I&C) systems could potentially compromise operation and safety of nuclear reactor power plants. This work utilizes the LOBO Nuclear CyberSecurity (LOBO NCS) Platform, developed recently at the University of New Mexico’s Institute for Space and Nuclear Power Studies, to investigate and contrast responses of an emulated PLC with OpenPLC and a commercial Allen-Bradley PLC. This is during nominal operation and simulated surge-in and surge-out transients of the pressurizer in a representative PWR plant. Investigations evaluate the effect of manipulating the control of linked PLCs to a physics-based Simulink model of the pressurizer on its operation during simulated transients. Simulated FDIAs introduced during the surge-in transient manipulate either input pressure or the rate of water spray into the pressurizer, to increase system pressure beyond nominal. Simulated FDIAs inconsistently overwrite holding registers of the PLCs during the duration of the attack. As a result, the immersed heaters and the water droplets spray nozzle switch off and on repeatedly, to reduce the pressure rise within the pressurizer. Manipulating a commercial Allen-Bradley PLC is more consistent than emulated OpenPLC and percentage of FDIAs’ successful overwrites increased with increasing input scan time of the PLC. Despite noted response differences iof emulated and hardware PLCs, results demonstrate using emulated PLCs in the LOBO NCS platform is suitable for current and future cybersecurity investigations. © 2022 Informa UK Limited, trading as Taylor & Francis Group.

关键词： programmable logic controllers

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programmable logic controllers and Petri Nets: A Comparative Study

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IFAC Proceedings Volumes 1982年第7期15卷 83-88页

作者： M. Silva S. Velilla Departamento de Automática Escuela Superior de Ingenieros Industriales Universidad de Zaragoza Spain

In a Petri Net (PN) model of a system, a small subset of transition can usually be fired. Therefore several special programmable logic controllers (PLCs) have been proposed looking for more performant simulation schemas. Some of them are general purpose microcomputer-based. Others are constructed using specialised microprocessors (microprogrammed or not). This paper presents a conceptual framework to systematize concepts introduced in different PLCs specifically designed for safe (1-bounded) PN simulation. To compare their “conceptual” performances, basic proposed schemas(and other new ones) were programmed on a same microcomputer (M 6801). The technique used for comparison of performances consists of: (1) building different data structures to represent PN and its marking and (2) building performance models using a small set of parameters that caracterizes the complexity of PN-models. It is shown that there is no “optimum” schema. The “best” one is a function of the net to be realised.

关键词： Computer control machine oriented languages microprocessors programming language programmable logic controllers performances Petri nets

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By the Numbers: Towards Standard Evaluation Metrics for programmable logic controllers' Defenses 2

By the Numbers: Towards Standard Evaluation Metrics for Prog...

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2024 International Workshop on Re-design Industrial Control Systems with Security

作者： Lopez-Morales, Efren Hopkins, Jacob Cardenas, Alvaro A. Abbasi, Ali Rubio-Medrano, Carlos Texas A&M Univ Corpus Christi Corpus Christi TX 78412 USA Univ Calif Santa Cruz Santa Cruz CA USA CISPA Helmholtz Ctr Informat Secur Saarbrucken Saarland Germany

ISBN: (纸本)9798400712265

Our modern society relies on important utility infrastructures such as water treatment plants and electric energy distribution grids. These infrastructures are managed by Industrial Control Systems (ICS), which include devices such as sensors, actuators and programmable logic controllers (PLCs). PLCs are a key component of ICS as they serve as a bridge connecting the cyber and physical worlds. A cyberattack on a PLC could have disastrous real-world consequences, such as longstanding energy blackouts. Researchers have produced a plethora of security defenses in order to safeguard PLCs from cyberattacks, e.g., PLC-specific Intrusion Detection Systems (IDS). However, most of these defenses report incomplete or no performance evaluation metrics. Worse, the defenses that do report metrics evaluate them in an, ad-hoc way without providing details. As a consequence, PLC defenses cannot be compared or built upon, which is one of the main ways science progresses. It also makes it difficult to assess the effectiveness of such defenses against attacks. In this paper, we propose a standard set of performance evaluation metrics designed specifically for PLC security defenses. We propose three types of metrics: security, overhead, and effectiveness metrics. We then lay out what are the challenges faced when collecting these metrics, e.g., the heterogeneity of PLC architectures, and provide recommendations on how these challenges can be addressed to obtain accurate metrics. Obtaining and reporting these metrics will enable researchers to move PLC security research forward ultimately improving the security of ICS and our critical infrastructure.

关键词： programmable logic controllers Cyber-Physical Systems Industrial Control Systems Security

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Changeability of Manufacturing Automation Systems using an Orchestration Engine for programmable logic controllers 15

Changeability of Manufacturing Automation Systems using an O...

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15th IFAC Symposium on Information Control Problems in Manufacturing

作者： Buehrer, Ulrich T. Legat, Christoph Vogel-Heuser, Birgit Tech Univ Munich Inst Automat & Informat Syst Garching Germany

To allow companies of the manufacturing domain to satisfy: customer demands and withstand increasing global competition, production automation processes have to become more efficient, stable and flexible. For this purpose. aspects of changeability and adaptiveness of automation systems have to be considered. Within this paper, a concept for an Orchestration Engine is proposed, which aims at providing the required degrees of flexibility within the field level control software. This Orchestration Engine is able to flexibly adapt its behavior during operation and is also able to adapt to physical changes of the production environment. For the implementation of this approach, existing concepts and technologies of model-driven engineering are utilized as a starting point for system modelling and automatic code generation, which is realized by model to text transformations. In order to allow application of the proposed concept to existing PLCs, requirements of the predominant IEC 61131-3 standard, such as cyclic execution, are taken into account. (C) 2015, IFAC (International Federation or Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

关键词： Factory automation flexible manufacturing systems models programmable logic controllers

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Functionalities of multi-agent systems in programmable logic controllers

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IFAC-PapersOnLine 2016年第30期49卷 60-64页

作者： Peixoto, João Alvarez Pereira, Carlos Eduardo de Oliveira, José Barata Federal University of Rio Grande do Sul Porto Alegre Brazil Electrical Engineering Department Federal University of Rio Grande do Sul Porto Alegre Brazil Electrical Engineering Department New University of Lisboa Lisboa Portugal

The consumer market ever more calls for diversified products in small batches and the industry lacks production systems that meet the demands with efficiency and ability to adapt quickly. Integrated manufacturing systems implemented have their management for programmable logic controllers and electrical interconnections, control logic and satisfactory robustness, but they do not attend the needs of diversity and flexibility in production. The solutions to these needs refer the company to migrate to the use of new technologies of control, circuit and logic. However, for an industry migrates is a very big and expensive step. Then, there is an urgent need for methods that implement the interface between logic controllers and multi-agent systems in order to evolve an integrated manufacturing system taking advantage of all electrical circuitry, control logic and the logic controller that installs itself, taking advantage of the self-adapting characteristics that the multi-agent systems provide. © 2016

关键词： Multi agent systems Adaptive systems Agile manufacturing systems Computer circuits controllers logic circuits programmable logic controllers Programmed control systems agility Electrical circuitries Electrical interconnections Industrial manufacturing Integrated manufacturing systems Production system Self adaptive system self x

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Usability Study of Security Features in programmable logic controllers 24

Usability Study of Security Features in Programmable Logic C...

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4th European Symposium on Usable Security

作者： Li, Karen Ramokapane, Kopo M. Rashid, Awais Univ Bristol Bristol Avon England

ISBN: (纸本)9798400717963

programmable logic controllers (PLCs) drive industrial processes critical to society, for example, water treatment and distribution, electricity and fuel networks. Search engines, e.g., Shodan have highlighted that PLCs are often left exposed to the Internet, one of the main reasons being the misconfigurations of security settings. This leads to the question - why do these misconfigurations occur and, specifically, whether usability of security controls plays a part? To date, the usability of configuring PLC security mechanisms has not been studied. We present the first investigation through a task-based study and subsequent semi-structured interviews (N=19). We explore the usability of PLC connection configurations and two key security mechanisms (i.e., access levels and user administration). We find that the use of unfamiliar labels, layouts and misleading terminology exacerbates an already complex process of configuring security mechanisms. Our results uncover various (mis-) perceptions about the security controls and how design constraints, e.g., safety and lack of regular updates due to long term nature of such systems, provide significant challenges to realization of modern HCI and usability principles. Based on these findings, we provide design recommendations to bring usable security in industrial settings at par with its IT counterpart.

关键词： programmable logic controllers Usability Security Mechanisms Security Configurations

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Changeability of Manufacturing Automation Systems using an Orchestration Engine for programmable logic controllers

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IFAC-PapersOnLine 2015年第3期48卷 1573-1579页

作者： Bührer, Ulrich T. Legat, Christoph Vogel-Heuser, Birgit Institute of Automation and Information Systems Technische Universität München Garching near Munich Germany

To allow companies of the manufacturing domain to satisfy customer demands and withstand increasing global competition, production automation processes have to become more efficient, stable and flexible. For this purpose, aspects of changeability and adaptiveness of automation systems have to be considered. Within this paper, a concept for an Orchestration Engine is proposed, which aims at providing the required degrees of flexibility within the field level control software. This Orchestration Engine is able to flexibly adapt its behavior during operation and is also able to adapt to physical changes of the production environment. For the implementation of this approach, existing concepts and technologies of model-driven engineering are utilized as a starting point for system modelling and automatic code generation, which is realized by model to text transformations. In order to allow application of the proposed concept to existing PLCs, requirements of the predominant IEC 61131-3 standard, such as cyclic execution, are taken into account. © 2015, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

关键词： programmable logic controllers

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Power Grid Safety Control via Fine-Grained Multi-Persona programmable logic controllers

Power Grid Safety Control via Fine-Grained Multi-Persona Pro...

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IEEE International Conference on Smart Grid Communications (SmartGridComm)

作者： Salles-Loustau, Gabriel Garcia, Luis Sun, Pengfei Dehnavi, Maryam Zonouz, Samara Rutgers State Univ Elect & Comp Engn Dept New Brunswick NJ 08901 USA

ISBN: (纸本)9781538609439

Trustworthy and safe operation of the power grid critical infrastructures relies on secure execution of low-level substation controller devices such as programmable logic controllers (PLCs). Currently, there are very few security protection solutions deployed on these devices to ensure provenance control: to execute controller code on the device that is developed by trusted parties and complies with safety/security policies that are defined by the code developer as well as the power grid operators. Resource-limited PLC controllers have been becoming increasingly popular among not only legitimate system operators, but also malicious adversaries such as the most recent Stuxnet and BlackEnergy malware that caused various damages such as unauthorized infrastructural safety and integrity violations. We present PLCtrust, a domain-specific solution that deploys virtual micro security-perimeters, so-called capsules, and the corresponding device-level runtime power system-safety policy enforcement dynamically. PLCtrust makes use of data taint analysis to monitor and control data flow among the capsules based on data owner-defined policies. PLCtrust provides the operators with a transparent and lightweight solution to address various safety-critical data protection requirements. PLCtrust also provides the legitimate third-party controller code developers with a taint-aware programming interface to develop applications in compliance with the dynamic power system safety/security policies. Our experimental results on real-world settings show that PLCtrust is transparent to the end-users while ensuring the power grid safety maintenance with minimal performance overhead.

关键词： Security Power grids Safety Substations Power system dynamics Monitoring Power grids Power system dynamics Substations programmable logic controllers Consumer safety safety Security Hyalin Security measures controllers CAPSULES Policies Safe handling

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Virtual reality - An approach to improve the generation of fault free software for programmable logic controllers (PLC)

Virtual reality - An approach to improve the generation of f...

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2nd IEEE International Conference on Engineering of Complex Computer Systems / 6th CSESAW / 4th IEEE RTAW / SES 96

作者： Spath, D Osmers, U INST MACHINE TOOLS & PROD SCI D-76128 KARLSRUHEGERMANY

ISBN: (纸本)0818676140

Software development for programmable logical controllers is usually based on low-level languages such as the instruction list or the ladder diagram. At the same time, the programmer looks at a machine or an assembly system in a bit-oriented way;he translates the operational sequences into logical and/or time based combinations of binary signals described by the means of Boolean algebra. This classical method causes a lot of problems in reality so it should be improved. It is the aim of the report to show a way developing PLC-software graphically and interactively within a Virtual Reality (VR) based system (VPLC).

关键词： programmable logic controllers

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