The PLC (programmable logic controller) has been widely used in the industrial world as a controller for manufacturing systems, as a process controller and so on. The conventional PLC has been designed and verified as...
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The PLC (programmable logic controller) has been widely used in the industrial world as a controller for manufacturing systems, as a process controller and so on. The conventional PLC has been designed and verified as a pure Discrete Event System (DES) by using an abstract model of a controlled plant. In verifying the PLC, however, it is also important to take into account the physical behavior (e.g. dynamics, shape of objects) of the controlled plant in order to guarantee such important factors as safety. This paper presents a new verification technique for the PLC-based control system, which takes into account these physical behaviors, based on a Hybrid Dynamical System (HDS) framework. The other key idea described in the paper is the introduction of the concept of signed distance which not only measures the distance between two objects but also checks whether two objects interfere with each other. The developed idea is applied to illustrative material handling problems, and its usefulness is demonstrated.
Modern industrial control systems (ICSs) regulate operations over a variety of different applications. Of most interest to national security is the role ICSs play in the management of critical infrastructure (CI) such...
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ISBN:
(纸本)9781909507111
Modern industrial control systems (ICSs) regulate operations over a variety of different applications. Of most interest to national security is the role ICSs play in the management of critical infrastructure (CI) such as the national power grid, water treatment, and chemical industry. The control systems used in such sectors are developing into highly networked collections of distributed devices. Unfortunately, security has only recently become a topic of major concern for these devices. This leaves many implementations without secure configurations due to their long lifespan compared to the rate of advancing threats. In the paradigm of ICSs, programmable logic controllers (PLCs) represent the front line between the cyber world and physical systems. Attacks like Stuxnet have already proven the effectiveness of cyber-physical attacks by altering and disguising PLC programming, but the next generation of threats will likely focus on PLC firmware. Just as traditional computer malware evolved to hide itself using operating system-level rootkits, so will ICS attacks evolve to embed themselves in the PLC equivalent: the firmware. Since little research has been done in the area of PLC firmware security, this paper begins by addressing the related security concerns. One such concern is the application of digital forensics to a potential incident of ICS attack. Forensic investigations of digital devices have traditionally been limited to the analysis of typical computer systems like desktops or laptops. As forensic capabilities begin to expand into the scope of embedded devices like smartphones, parallels can be drawn to PLCs that will enable the development of more advanced forensic tools and processes. By performing a firmware analysis through reverse engineering, a PLC can be exploited for both malicious and forensic purposes. This paper discusses the techniques and procedures required to access, inspect, and manipulate firmware for an Allen-Bradley PLC to suit the purpos
The purpose of this project is to create a new lab apparatus for the Machine Element Design course at the McCoy School of Engineering at Midwestern State University. The apparatus is designed so that future students c...
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ISBN:
(纸本)9780791887653
The purpose of this project is to create a new lab apparatus for the Machine Element Design course at the McCoy School of Engineering at Midwestern State University. The apparatus is designed so that future students can visualize and understand how a car transmission system works, specifically in regards to the concepts of mechanical advantage, gear ratios and efficiency. The transmission control system utilizes pneumatic-mechanical clutches and electro-mechanical brakes to realize one of the six possible gear ratios. The system is automated by a programmable logic controller (PLC) that is able to shift the transmission into the different gear configurations and allow the students to determine the mechanical advantage and the efficiency of each configuration. To achieve the stated goals, necessary modifications have been made to a transmission built and modified by previous senior design groups. The current team of senior design students used the SolidWorks CAD software to design a new clutching and braking system that works more effectively. The team also created a new PLC program. The PLC controls the pneumatic cylinders for the clutch system, the linear actuators for the braking system, and it reads and displays the torque readings from two transducers. The PLC is used in conjunction with a Human Machine Interface (HMI). The HMI has been programmed so that the user may select a gear configuration simply by tapping a digital button on the touch screen.
programmable logic controller (PLC) is a reliable platform for regulatory control in industrial environment. Capability of PLC as an automation solution platform is getting enhanced over the years. Advancements in PLC...
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ISBN:
(纸本)9781479977871
programmable logic controller (PLC) is a reliable platform for regulatory control in industrial environment. Capability of PLC as an automation solution platform is getting enhanced over the years. Advancements in PLC capability open up possibility of deploying advanced control and optimization solutions on PLC. Optimization solver is primary building block of the advanced automation solutions;feasibility of deploying open source optimization solvers on PLC is uncertain because of platform related constraints. This work evaluates feasibility of deploying open source optimization solvers on PLC and highlights deployment challenges for PLC platform. Optimization complexity is varied using widely used generalized test functions to assess limitations of PLC platform. A realistic case study of parallel compressor train load allocation optimization is presented to validate the analysis findings and discuss a practical application of optimization on PLC platform.
This paper evaluates experimentally the position control ability of a pneumatic cylinder by using pneumatic proportional valves and a programmable logic controller. An experimental system consisting of a double acting...
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programmable logic controllers (PLCs) are specialized computers for automating a wide range of cyber-physical systems. Since these systems are often safety-critical, software running on PLCs need to be free of program...
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ISBN:
(纸本)9781450351058
programmable logic controllers (PLCs) are specialized computers for automating a wide range of cyber-physical systems. Since these systems are often safety-critical, software running on PLCs need to be free of programming errors. However, automated tools for testing PLC software are lacking despite the pervasive use of PLCs in industry. We propose a symbolic execution based method, named SYMPLC, for automatically testing PLC software written in programming languages specified in the IEC 61131-3 standard. SYMPLC takes the PLC source code as input and translates it into C before applying symbolic execution, to systematically generate test inputs that cover both paths in each periodic task and interleavings of these tasks. Toward this end, we propose a number of PLC-specific reduction techniques for identifying and eliminating redundant interleavings. We have evaluated SYMPLC on a large set of benchmark programs with both single and multiple tasks. Our experiments show that SYMPLC can handle these programs efficiently, and for multi-task PLC programs, our new reduction techniques outperform the slate-of-the-art partial order reduction technique by more than two orders of magnitude.
Rice improvement breeding is one of the most important research fields in China. With the development of modern rice breeding technology, hundreds to thousands of new varieties are produced daily, creating the impetus...
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ISBN:
(纸本)9783642272745
Rice improvement breeding is one of the most important research fields in China. With the development of modern rice breeding technology, hundreds to thousands of new varieties are produced daily, creating the impetus for rapid plant phenotyping evaluation. However, traditional measurement is inefficiency, contact-interferential, and lack-objectivity. Thus a high-throughput and automatic extraction system for rice plant is imperative. In this article we developed a rice phenotyping automatic extraction system and designed the automatic control for the system based on programmable logic controller (PLC). Subsequently, the prototype was test under industrial conditions continuous 24 h workdays and the error probability was less than 0.01%. In sum, base on PLC, we provide an efficient and stable automatic control system for pot-grown rice phenotyping inspection.
This paper presents novel contributions to the field of process mining in programmable logic controllers (PLCs). One significant contribution is the proposal of a new event source for process mining, which can be used...
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ISBN:
(纸本)9789819712731;9789819712748
This paper presents novel contributions to the field of process mining in programmable logic controllers (PLCs). One significant contribution is the proposal of a new event source for process mining, which can be used when PLC logs are absent or insufficient. This research also demonstrated the feasibility of converting the memory states of PLCs into event logs, which can be used to construct a process model of the PLC. This approach requires neither detailed knowledge about control logic nor source code of PLC. The paper also evaluates the use of process confrontation as a means of detecting abnormal or cyber-attacks on PLCs, which can provide an effective method for identifying abnormal behaviors and deviations from the normal process flow. Finally, the paper explores other optimization ideas for process mining in PLCs, provides useful insights, and offers potential solutions for extending research in this area.
The study presents details related to the structure of a two-processor CPU designed for a PLC. The CPU is made up of a 1-bit processor combined with a 32-bit processor and is capable of executing a control routine dev...
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ISBN:
(纸本)9781538667682
The study presents details related to the structure of a two-processor CPU designed for a PLC. The CPU is made up of a 1-bit processor combined with a 32-bit processor and is capable of executing a control routine developed in the IL language according to requirements of the IEC 61131-3 standard. In addition, the CPU is provided with functionalities necessary to handle such functional modules as edge detectors, flip-flops, timers and counters. A dedicated module of interface memory for data exchange was developed to enable synchronization of data transfer between the two processors that are operated in absolute independent and asynchronous way. The entire CPU was implemented in resources of a programmable (FPGA) chip from the Artix-7 family offered by Xilinx. The last part of the study comprises results obtained for execution times for example control routines and these times are compared against respective results achieved for other CPU structures.
Industries rely on numerous processes that require effective control. Whereas conventional controllers are commonly used, they may not be suitable for highly complex processes. In such cases, a feasible solution is to...
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ISBN:
(纸本)9798350315684
Industries rely on numerous processes that require effective control. Whereas conventional controllers are commonly used, they may not be suitable for highly complex processes. In such cases, a feasible solution is to employ model predictive control (MPC), which may offer advanced capabilities to effectively regulate complex processes and optimize performance. This paper focuses on the study and the development of a MPC based on dynamic matrix control (DMC), which is implemented within a programmable logic controller (PLC). In order to evaluate the performance of the controller, a B&R Automation commercial PLC and a didactic level plant were employed. A comparison was made between the real process results and the simulation outcomes obtained using Matlab (R) software.
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