This paper describes the application of programmable logic controllers (PLCs) to control and protection of bulk power and regional supply substations. PLC requirements are discussed and the concept of ''zones ...
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This paper describes the application of programmable logic controllers (PLCs) to control and protection of bulk power and regional supply substations. PLC requirements are discussed and the concept of ''zones of control'' is explained as applied to standard PP&L substation arrangements. The use of a peer-to-peer communication network between logiccontrollers and other substation equipment is also discussed. Details of an installation completed in spring, 1992, are presented, including experience acquired from power system faults.
Total automated process control of a full-scale wastewater treatment facility was successfully achieved using a programmable logic controller. This facility includes three (3) sequencing batch reactors, three (3) down...
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Total automated process control of a full-scale wastewater treatment facility was successfully achieved using a programmable logic controller. This facility includes three (3) sequencing batch reactors, three (3) downflow pressure filters, and two (2) ultraviolet disinfection units. The control system routinely manipulates 68 equipment items within the plant, as well as continuously monitoring the operational status of all such equipment. The controller also handles emergency startup/shutdown conditions, cycling of redundant equipment items, and equipment failure situations. In addition, telephonemodem communication with the controller can be obtained to facilitate remote system evaluation and troubleshooting. National recognition of the engineering design excellence and innovation applied to this unique automated facility was recently awarded by the American Consulting Engineers Council, with its designation of this plant as one of the top ten engineering projects within the United States for 1986.
This paper introduces a scheduling method for a programmable logic controller (PLC) working under a multi-tasking, multi-processor and network-based I/O subsystem environment. We construct a generic architectural and ...
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This paper introduces a scheduling method for a programmable logic controller (PLC) working under a multi-tasking, multi-processor and network-based I/O subsystem environment. We construct a generic architectural and behavioral model of a PLC and extract precise timing constraints. A heuristic algorithm is developed to satisfy the two objectives, timing constraints and low resource occupation at the same time. A synchronization scheme between program execution and data transmission is also developed, which enables the developed algorithm to accommodate multi-processor PLCs. We analyze the performance and implement the proposed method to demonstrate feasibility.
In this study, a digital fault location and monitoring technique using programmable logic controller (PLC) for primary overhead power distribution networks is presented. This technique employs pre- and post-fault curr...
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In this study, a digital fault location and monitoring technique using programmable logic controller (PLC) for primary overhead power distribution networks is presented. This technique employs pre- and post-fault current and voltage information along with data from the laterals. By using lateral current data transferred through shielded coaxial cables to the substation, the possibility of multiple fault point locations are eliminated. The effectiveness of this method is verified through Electromagnetic Transients Program (EMTP) simulations. (C) 2011 Elsevier Ltd. All rights reserved.
In this paper, an architecture of the RISC processor for programmable logic controllers is proposed. Execution characteristics of relay ladder logic (RLL) are analyzed with various application programs in order to det...
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In this paper, an architecture of the RISC processor for programmable logic controllers is proposed. Execution characteristics of relay ladder logic (RLL) are analyzed with various application programs in order to determine an optimal architecture for programmable logic controllers (PLCs). A conditional execution mechanism is developed to prevent pipeline hazards caused by the inherent execution behavior of RLL. Instruction sets of three different architectural models are defined. Translators, assemblers, and simulators are developed for three models to evaluate performance and to choose an optimal architecture for PLCs. The proposed processor, which has an accumulator architecture with a four-stage pipeline, exhibits desirable performance much higher than that of recent commercial PLCs.
Critical infrastructures are making increasing use of digital technology for process control. While there are benefits, such as increased efficiency and new functionality, digitalization also introduces the risk of cy...
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Critical infrastructures are making increasing use of digital technology for process control. While there are benefits, such as increased efficiency and new functionality, digitalization also introduces the risk of cyber-attacks to systems that support critical functions. A valuable target in these Industrial Control Systems (ICSs) are the programmable logic controllers (PLCs) controlling the machinery that manages a physical process. PLCs have proven to be vulnerable to a range of cyber-attacks in the past;however, newer technologies such as embedded servers and virtualization have the potential to improve this situation and be used to monitor a PLC's function. In this article, the implementation of a Host-based Intrusion Detection System (HIDS) for a modern PLC is described. This method uniquely makes use of native technologies on the PLC to monitor a dynamic simulated process in real time. Both the PLC's integrity (checksum, file size, etc.) and the process control are monitored to determine whether the PLC has been compromised in a cyber-attack. The proposed solution detects a range of attacks, even when the PLC's control logic is compromised and-unlike previous PLC HIDS methods-requires no modification of the underlying PLC technology.
The paper presents the use of the TM221CE16R and TM241CEC24R programmable machines and the HMISTU855 machine-machine interface. The Learning Platform allows for the study of programming differences between SoMachine B...
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ISBN:
(纸本)9781479975143
The paper presents the use of the TM221CE16R and TM241CEC24R programmable machines and the HMISTU855 machine-machine interface. The Learning Platform allows for the study of programming differences between SoMachine Basic and SoMachine V4.3 software. Another aspect is the programming of HMI with Vijeo Designer 6.2 Software. The set of sensors, the programmable automatic and the user interface involve the creation of various applications. The educational platform monitors the status of the input / output variables and provides solutions for the study, simulation and optimization of production processes.
Recently published scan data on Shodan shows how 105K Industrial Control Systems (ICSs) around the world are directly accessible from the Internet. In particular, highly sensitive components, such as programmable Logi...
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ISBN:
(纸本)9798400707728
Recently published scan data on Shodan shows how 105K Industrial Control Systems (ICSs) around the world are directly accessible from the Internet. In particular, highly sensitive components, such as programmable logic controllers (PLCs), are potentially accessible to attackers who can implement several kinds of attacks. On the other hand, to accomplish non-trivial cyber-physical attacks the attacker must possess a suffcient degree of process comprehension on the physical processes within the target ICS. In this paper, we explore the feasibility of designing obfuscation strategies to prevent the attacker from comprehending the behavior of the physical process within an ICS by accessing PLC memory registers. We propose two generic obfuscation strategies for PLC memories, involving memory registers, PLC code, and simulated physical processes controlled by the obfuscated PLCs. We then measure the effectiveness of the proposed obfuscation strategies in terms of potency, resilience, and cost on a non-trivial case study.
The rise of smart factories is driving the complete automation of manufacturing environments, making anomaly detection a more important task than ever. With highly intelligent equipment deployed on fully-automated pro...
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ISBN:
(纸本)9798350368567;9798350368550
The rise of smart factories is driving the complete automation of manufacturing environments, making anomaly detection a more important task than ever. With highly intelligent equipment deployed on fully-automated production lines, even a slight anomaly may seriously impact the entire manufacturing process. However, most industrial data containing slight anomalous features exhibits strong correlations that are not fully exploited by existing machine learning models. In general, the anomaly detection model needs to run within programmable logic controllers (PLCs) since it is the main controller of the intelligent equipment, and PLCs have limited resources making it difficult to execute larger models effectively. To address the challenge, we propose a graph anomaly detection method in programmable logic controllers based on service computing (PCSC). The model establishes a data relationship graph through clustering and then feeds it into a neural network with a symmetric structure consisting of graph convolutional layers and LSTM units. This approach enables the analysis of correlations within industrial data and facilitates the extraction of slight abnormal features. For efficient execution of the model, we establish service computing nodes in the PLCs that support model splitting. We tested the model on several publicly available datasets and an actual dataset from an injection molding production line. The results show that the model performs well on different datasets.
The adoption of service-oriented architectures based on web services in industrial application domains enables the seamless integration of business software with manufacturing tasks and promises increased interoperabi...
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ISBN:
(纸本)9781424468508
The adoption of service-oriented architectures based on web services in industrial application domains enables the seamless integration of business software with manufacturing tasks and promises increased interoperability. To be able to invoke a manufacturing task running on a programmable logic controller (PLC) as a web service from a business application, the SOAP4PLC engine has been proposed. In this paper, an extension of the SOAP4PLC engine is presented to invoke a web service based business application from a PLC application. A use case is shown in which the extended SOAP4PLC engine is used to interface a PLC application concerned with realizing the functionality of a charging station for electrical vehicles with a web service based accounting system.
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