Distributed control systems and computer aided manufacturing are a few of the contemporary factory automation tools of today. programmablelogic controller (PLC) manufacturers are offering both soft logic, and a choic...
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Distributed control systems and computer aided manufacturing are a few of the contemporary factory automation tools of today. programmablelogic controller (PLC) manufacturers are offering both soft logic, and a choice of platforms to run it on. PLCs application in the process industry is being further enhanced by process-based technology. Software tools are a vital component for today's PLC user. Hence, every major industry is reconstructing its plant layout to join the trend of emerging factory automation by connecting everything to the Internet.
The implementation of programmable logic controllers (PLC) based control system in a gas transmission pipeline by Delevan compressor station of Pacific gas and electric company is discussed. The station control system...
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The implementation of programmable logic controllers (PLC) based control system in a gas transmission pipeline by Delevan compressor station of Pacific gas and electric company is discussed. The station control system allows operators to designate each unit as the base unit or as a stand by. The system also allows the various units to operate in parallel into the header and change of unit designations while the units are on line.
programmable logic controllers (PLCs) have a major role in assembly automation. They employ a novel language called ladder logic. The ladder logic was developed based on the relay ladder logic wiring diagram. Five cat...
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programmable logic controllers (PLCs) have a major role in assembly automation. They employ a novel language called ladder logic. The ladder logic was developed based on the relay ladder logic wiring diagram. Five categories of PLCs are available in various capabilities, from micro PLCs to very large PLCs. The parts of the PLCs include the processor, power supply, and input/output modules. A number of factories have been using PLCs to cut production costs and increase quality.
programmablelogic Controller's (PLC's) have been utilized in Power Plant control for over two decades. Until recently this has been limited to discrete logic systems, and systems with a small regulatory requi...
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programmablelogic Controller's (PLC's) have been utilized in Power Plant control for over two decades. Until recently this has been limited to discrete logic systems, and systems with a small regulatory requirement. Advancement in programming languages and graphic packages and combined with the PLC's historic ruggedness to produce a platform that rivals the DCS in capability, with a very attractive footprint and cost structure.
In this paper, a scheduling algorithm is proposed for a programmablelogic controller (PLC) with remote I/Os, assuming the multi-tasking facilities. Since sequence programs are executed on the application processor an...
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In this paper, a scheduling algorithm is proposed for a programmablelogic controller (PLC) with remote I/Os, assuming the multi-tasking facilities. Since sequence programs are executed on the application processor and I/O data are transmitted by the network processor concurrently, the proposed algorithm schedules the data transmission as well as the sequence program execution. The suggested algorithm guarantees the bounded response time, which is the one third of the worst case response time in the absence of scheduling. Computer simulation shows that the algorithm can be easily applied to a real PLC without critical constraints on utilization of resources and inter-relation among tasks.
The intelligent analogue operation and fault detection for PLC logic circuits are implemented in expert system technology, and special circuits and their application are introduced in this paper. The designation resol...
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The intelligent analogue operation and fault detection for PLC logic circuits are implemented in expert system technology, and special circuits and their application are introduced in this paper. The designation resolves the contradiction between fewer PLC programming panels and more users. The practicability and the efficiency of the means mentioned in the paper have been proved by the results of simulated operation.
An approach to the formal verification of logiccontrollers for processes with switched continuous dynamics is presented. The method builds on modular, timed discrete event models of the plant and the controller. Subs...
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An approach to the formal verification of logiccontrollers for processes with switched continuous dynamics is presented. The method builds on modular, timed discrete event models of the plant and the controller. Subsystems with continuous dynamics are approximated algorithmically. The formal verification consists of determining the reachable discrete states of the resulting model and comparing it to a set of undesired states. For this purpose, the tool HyTech is applied. The approach is illustrated by the treatment of a process engineering example. (C) 1999 Elsevier Science Ltd. All rights reserved.
This paper addresses the potential applications of power-line-carrier (PLC) communications technology within the field of industrial plant/equipment control. The special needs and requirements for this application (in...
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This paper addresses the potential applications of power-line-carrier (PLC) communications technology within the field of industrial plant/equipment control. The special needs and requirements for this application (in terms of such factors as system integrity and response times) will be considered in comparison with those for other types of PLC application. Existing PLC technologies will be discussed and their suitability (or otherwise) for this application considered.
A tool environment for the formal verification of logiccontrollers for switched continuous systems is presented. It supports a model-based verification approach which builds on different models of the controller and ...
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A tool environment for the formal verification of logiccontrollers for switched continuous systems is presented. It supports a model-based verification approach which builds on different models of the controller and the plant. The architecture consists of a hierarchical plant modeling editor, a translator for the input of controllers given in IL code, and an interface to integrate available model-checkers, e.g., for Timed Automata. In the paper, each architecture component is described and the modeling interface is illustrated by an example.
An automated continuous measurement system for the monitoring of formaldehyde (HCHO) and acetaldehyde (CH3CHO) in the urban atmosphere was developed by using an annular diffusion scrubber in conjunction with a high-pe...
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An automated continuous measurement system for the monitoring of formaldehyde (HCHO) and acetaldehyde (CH3CHO) in the urban atmosphere was developed by using an annular diffusion scrubber in conjunction with a high-performance liquid chromatograph (HPLC). With this technique, atmospheric HCHO and CH3CHO were effectively collected by the annular diffusion scrubber which consists of a porous polytetrafluoroethylene (PTFE) tube disposed concentrically within a Pyrex-glass tube and a scrubbing solution. 2,4-Dinitrophenylhydrazine (DNPH) was selected as the scrubbing solution for collecting HCHO and CH3CHO, which are derivatized to 2,4-dinitrophenylhydrazone-formaldehyde (DNPH-HCHO) and 2,4-dinitrophenylhydrazone-acetaldehyde (DNPH-CH3CHO), respectively. An aliquot of the sample solution was automatically injected into an HPLC equipped with a semi-micro ODS column and a UV-VIS detector for separating and determining DNPH-HCHO and DNPH-CH3CHO. All the operations are sequenced by a programmable controller, and automated continuous measurements are performed with a typical temporal resolution of 1 h. The collection efficiencies of HCHO and CH3CHO were about 97% and 93%, respectively, at an air flow rate of 0.2 L/min. The lower detection limits (3 sigma of the blank hydrazones) of HCHO and CH3CHO were 0.05 ppbv and 0.10 ppbv, respectively, in the case of 12-L air sample volume. Analytical response of a standard solution of DNPH-HCHO and DNPH-CH3CHO by the HPLC during a 10-day continuous measurement was unchanged and the relative standard deviation (RSD) was < 1.0%. Interferences from O-3 and NO2 were insignificant in this annular diffusion scrubber method. Both for HCHO and CH3CHO measurements, concentrations from this developed system well agreed with those measured by a DNPH Silica cartridge method.
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