As programmable logic controllers (PLCs) are widely used in the digital instrumentation and control (I&C) systems of nuclear power plants (NPPs), the safety of PLC software has become the most important considerat...
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As programmable logic controllers (PLCs) are widely used in the digital instrumentation and control (I&C) systems of nuclear power plants (NPPs), the safety of PLC software has become the most important consideration. In this work, we propose a method to perform effective verification activities on the traceability analysis and the software design evaluation in the software design phase. In order to perform the traceability analysis between Software Requirement Specification (SRS) written in a natural language and Software Design Specification (SDS) written in Function Block Diagram (FBD), this method uses Extended-Structured Decision Table (ESDT). ESDTs include information related to the traceability analysis from SRS and SDS, respectively. Through comparing with two ESDTs, an effective traceability analysis can be achieved. For the software design evaluation, we use model checking as a formal verification method. FBD-style design specification is translated into Symbolic Model Verifier (SMV) input language and then the FBD-style design specification can be formally analyzed using SMV model checker.
The contribution describes a distributed control system design method that is developed at Department of Measurement and Control, TU Ostrava. The method is focused in distributed control systems with programmable cont...
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We investigate the class of disjoint NP-pairs under different reductions. The structure of this class is intimately linked to the simulation order of propositional proof systems, and we make use of the relationship be...
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ISBN:
(纸本)3540240586
We investigate the class of disjoint NP-pairs under different reductions. The structure of this class is intimately linked to the simulation order of propositional proof systems, and we make use of the relationship between propositional proof systems and theories of bounded arithmetic as the main tool of our analysis. Specifically we exhibit a pair which is complete under strong reductions for all disjoint NP-pairs representable in a theory. We use these pairs to explain the simulation order of NP-pairs under these reductions. As corollaries we also get simplified proofs of results obtained earlier in [3] and [5].
A programmable logic controllers (PLC) which include digital logic, timers, counters, interger math, real math and table lock-ups is discussed. The PLC had used digital I/O, analog I/O, high speed counter, thermocoupl...
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A programmable logic controllers (PLC) which include digital logic, timers, counters, interger math, real math and table lock-ups is discussed. The PLC had used digital I/O, analog I/O, high speed counter, thermocouples, remote I/O and PID control of a DC motor/tachometer arrangement. A studio classroom environment was created where students work on their laptops and short example ladder logic exercises to reinforce the PLC concepts. An increased confidence level among the students was observed and they also derived a very high level of satisfaction from this course.
This work explores various solutions to implement an application using runtime reconfigurable field programmable gate arrays (FPGA). The example is a mechatronic control system which has to adapt its behavior from tim...
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ISBN:
(纸本)0769521320
This work explores various solutions to implement an application using runtime reconfigurable field programmable gate arrays (FPGA). The example is a mechatronic control system which has to adapt its behavior from time to time. Our model is a task-graph where every task is associated with an hardware module characterized by its required FPGA resource and its execution time. We propose various mappings of the tasks onto the FPGA. For the implementation of the tasks themselves the computation technique known as distributed arithmetic is used. We achieve numerous alternatives with different resource consumptions and execution times for every task. We estimate these characteristics and compare them to synthesis results. The received values are used to get the characteristics of the over-all system. The results show that the optimal mapping depends on the application timing constrains, on the complexity of the tasks as well as on the reconfiguration speed of the used FPGA1.
A formal algebraic model of programmablelogic controller (PLC)-based control systems to formulate various kinds of optimization problems was developed. The model unifies the discrete logical behavior of Sequential Fu...
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A formal algebraic model of programmablelogic controller (PLC)-based control systems to formulate various kinds of optimization problems was developed. The model unifies the discrete logical behavior of Sequential Function Chart (SFC) and the continuous behavior of a plant harmoniously. The optimization problem of the sensor parameters, such as the location of the limit switch in the material handing system, are addresses based on the developed model. The optimization problem has been formulated by extending the proposed algebraic form with regarding the sensor parameters as constant states and by transforming the extended model into the Mixed logical Dynamical Systems (MLDS) form.
Due to the growing complexity of PLC programs there is an increasing interest in the application of formal methods in this area. Formal methods allow rigid proving of system properties in verification and validation. ...
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Due to the growing complexity of PLC programs there is an increasing interest in the application of formal methods in this area. Formal methods allow rigid proving of system properties in verification and validation. One way to apply formal methods is to utilize a formal design approach in PLC programming. However, for existing software that has to be optimized, changed, or ported to new systems there is the need for an approach that can start from a given PLC program. Therefore, formalization of PLC programs is a topic of current research. The paper outlines a re-engineering approach based on the formalization of PLC programs. The transformation into a vendor independent format and the visualization of the structure of PLC programs is identified as an important intermediate step in this process. It is shown how XML and corresponding technologies can be used for the formalization and visualization of an existing PLC program.
This paper presents the evaluation technique of the mean time to failure (MTTF) and reliability corresponding to a programmablelogic controller (PLC) structures such as a single controller, a dual controller and a tr...
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This paper presents the evaluation technique of the mean time to failure (MTTF) and reliability corresponding to a programmablelogic controller (PLC) structures such as a single controller, a dual controller and a triple modular redundancy (TMR) controller. The failure and repair period of PLCs are surveyed, and the failure rate of each unit composing a PLC is calculated. The MTTF of a single PLC system and a dual PLC system is computed with failure rate and compared. Reliability and MTTF with respect to a dual controller and a TMR controller are calculated and analyzed by using the Markov model in order to present the operation standards of a PLC.
This paper addresses the problem of improving immunization of programmable logic controllers (PLC) to electro-magnetic interference with impulsive characteristics. A filtering structure, based on Weighted Median (WM) ...
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In the Oil & Gas as well as Petrochemical industries there is an increased concern on the safety performance of the Safety Instrumented System (SIS) as one of the plant/equipment layer protection system. The Compr...
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In the Oil & Gas as well as Petrochemical industries there is an increased concern on the safety performance of the Safety Instrumented System (SIS) as one of the plant/equipment layer protection system. The Compressor Protection Control Panel (CPCP) plays an important role on the compressor protection system as the control panel controlling the start up, operation and shutdown system on the compressor unit. The current diagnostic capability on "general" PLC input output module opens chances to increase the diagnostic of the compressor protection system, which in turn will increase the safety and reliability. Copyright 2004 by ISA - The Instrumentation, Systems and Automation Society.
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