Petri nets have been extensively applied for specification, design, verification, performance evaluation, and simulation of discrete event control systems (DECS). This paper proposes a real-time stage Petri net (RTSPN...
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ISBN:
(纸本)0780372727
Petri nets have been extensively applied for specification, design, verification, performance evaluation, and simulation of discrete event control systems (DECS). This paper proposes a real-time stage Petri net (RTSPN), to represent the stage programming of a programmable logic controller (PLC) for DECS. The new technique is able to simplify the design process of the complex PLC program without considering the interlocking problem within the ladder diagram. An illustrated example is used to explore the new methodology. The proposed method contains the power and flexibility of the Petri net analysis. It is believed that this technique is significant for the industry practice.
This paper presents an overall view of the architecture and design of a programmable logic controller (PLC). The main objectives of the work are to design, develop, and implement a versatile PLC processor module (PLCP...
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This paper presents an overall view of the architecture and design of a programmable logic controller (PLC). The main objectives of the work are to design, develop, and implement a versatile PLC processor module (PLCPM) based on an industrial open bus architecture called VMEbus (IEEE 1014 Versa Module Euro-standard). The controller is inserted inside the VME crate and controls the industrial process via input and output modules that reside in the crate. The PLCPM is designed to be an intelligent module through the use of a Motorola MC68000 CPU. A method of distributed arbitration protocol, based on an algorithmic state-machine design approach, is added to the design of this module. This facility makes PLCPM suitable to work inside a VMEbus environment. The PLCPM therefore becomes adequate for use in multiprocessing PLC systems. The controller uses a host personal computer (IBM-PC) as a versatile and indispensable system component for process development, monitoring, control and supervision. Software and firmware programs are developed and written for both host-PC and PLCPM using standard C-language and 68000 assembly language, respectively. This results in a sequential control algorithm for the PLCPM and windowing user interface for the host-PC. Ladder diagram programming language is supported by this user interface. (C) 1998 Elsevier Science B.V.
The functions of the crawler for mining and driving are all remotely controlled from the control computers on the ship. Various sensors allow comprehensive monitoring of the performance of the crawler. The crawler com...
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ISBN:
(纸本)1880653567
The functions of the crawler for mining and driving are all remotely controlled from the control computers on the ship. Various sensors allow comprehensive monitoring of the performance of the crawler. The crawler computer is based on PC/104 modules in connection with a standard industrial field bus system (Interbus) for data acquisition and control. The software used in the sand mining system consists of the process visualisation software in the control room, the control software for development and implementation of the main control program, and the operating systems of the crawler computer and the control computers.
This paper proposes PC based data acquisition and load control system (DAALCS) to fulfill load. management functions for high voltage load customer. programmable logic controller (PLC) associated with digital power me...
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ISBN:
(纸本)0780347544
This paper proposes PC based data acquisition and load control system (DAALCS) to fulfill load. management functions for high voltage load customer. programmable logic controller (PLC) associated with digital power meter have been applied to fulfill major application functions of DAALCS. In the data acquisition subsystem,;two PLCs with redundant configuration are responsible for directly collecting power measurements via star connection telephone network with real time mode. 15 digital power meters with Standard RS485 protocol are installed on each building substation to record more than 20 parameters for data acquisition subsystem. In the load control subsystem, six sets of PLCs with the mixture of PLC network and RS 485 channel are constructed to execute load control schemes;The load control schemes compose of load shedding for demand monitoring, cycling on/off load control, timer control, and direct load control. The proposed system has been successfully installed and continuously operated on academic power system. The statistic data retrieved from data base shows that the DAALCS can effectively reduce the daytime peak load during summer season and significantly save electric energy consumption.
The poster describes the equipment based on PLC for measuring of effectiveness of the accumulator matters. Main part of the equipment is control system with programmablecontroller Tecomat TC 600. The controller provi...
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The poster describes the equipment based on PLC for measuring of effectiveness of the accumulator matters. Main part of the equipment is control system with programmablecontroller Tecomat TC 600. The controller provides measurement according to setting parameters and saves acquired data to the memory. The parameters could be set on the computer with SCADA system. This system also processes measured data. The results are time characteristics of charging and discharging of tested matter, values of effectiveness in each cycle.
The aim of this paper is to apply and adapt methods and formalisms from the computer science to the field of automation. It describes a method to enable formal verification of PLC programs written in the LD language (...
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The aim of this paper is to apply and adapt methods and formalisms from the computer science to the field of automation. It describes a method to enable formal verification of PLC programs written in the LD language (IEC 61131-3) . The principle of the method is to define an operational semantics for the language (description of the behavior of its primitives in terms of state automaton), to encode this definition using a symbolic model-checking tool and check if safety and liveness properties are held by the system. These properties are expressed using the LTL and CTL temporal logics.
The paper presents a module of PID controller builds in FPGA structure of Reconfigurable logiccontroller. It presents algorithms used to built the controller and implementation process. Implementation process shows t...
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The paper presents a module of PID controller builds in FPGA structure of Reconfigurable logiccontroller. It presents algorithms used to built the controller and implementation process. Implementation process shows the ways of minimising the controller structure and increasing it performance in FPGA structures. Finally it discuses achieved result.
Main topic of the poster is the communication between PLC Simatic S7 200 and SCADA system Intouch 7.0 via serial link RS 485. On side of the PLC is used freeport communication mode with our own protocol. The interface...
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Main topic of the poster is the communication between PLC Simatic S7 200 and SCADA system Intouch 7.0 via serial link RS 485. On side of the PLC is used freeport communication mode with our own protocol. The interface between PLC and Intouch is made by conversion program that use Dynamic Data Exchange (DDE). This makes possible with keeping protocol to communicate with other types of PLC&s too. In this manner is also possible to build a communication between several nodes.
The purpose of this paper is to present a programmable logic controller (PLC) control system that is applied to the main feedwater process of a pressurized water reactor, construct a structure that the alternative sys...
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ISBN:
(纸本)0780335457
The purpose of this paper is to present a programmable logic controller (PLC) control system that is applied to the main feedwater process of a pressurized water reactor, construct a structure that the alternative system is a hot backup to the operating system between PLC and the original analog instrument control system, overcome the draw backs of TI545 type PLC control module, and implement an advanced digital control algorithm to improve the control performance simultaneously. Successful results are obtained from this scheme. Implementation indicates that the PLC control system improves the performance of both steam generator water levels regulation and disturbance rejection.
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.
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