programmablelogic controller (PLC) is a control device whose only function is to manipulate the relays wired to its discrete output ports, according to the status of the switches wired to its discrete inputs. However...
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programmablelogic controller (PLC) is a control device whose only function is to manipulate the relays wired to its discrete output ports, according to the status of the switches wired to its discrete inputs. However, it soon became apparent that the computer, literally hidden under within the body of PLC, could be configured to process numeric data as well as on/off signals. Analog input and output ports were added to allow the PLC to read continuous values from meters in the plant and to return calculated values to actuators such flow, temperature, pressure regulators. From there, it was relatively simple matter to create completely automatic feedback controls loops using the PLC as the controller. The PID algorithm quickly became the standard control strategy for the PLC, as it had for earlier DCSs and single-loop controllers.
This paper proposes an approach to implement a programmablelogic Controller (PLC) from real-time software components following the International Industrial Standard IEC61499. According to this standard, a Function Bl...
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The ARC Advisory Group, Dedham, Mass. has reported $6 billion worldwide sales of PLCs, I/O and related products and services. The reason for the success of older PLCs over new generation PLCs is that they are robust, ...
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The ARC Advisory Group, Dedham, Mass. has reported $6 billion worldwide sales of PLCs, I/O and related products and services. The reason for the success of older PLCs over new generation PLCs is that they are robust, can survive in hazardous conditions and there is no downtime as a result of PLC failure. Modern PLCs are embedding ethernet and web server capability into their hardware which ensures full compatibility with TCP/IP, SMP and FTP protocols.
The capabilities of programmable logic controllers (PLC) and weight controllers are maximized and costs are reduced when a strong bidirectional interface is used. The PLC is capable of performing a variety of tasks, b...
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The capabilities of programmable logic controllers (PLC) and weight controllers are maximized and costs are reduced when a strong bidirectional interface is used. The PLC is capable of performing a variety of tasks, but a wiser solution is to offload some functions to a dedicated weight controller. The basics of a good process weighing system cannot be ignored, but placement of weight control and decision responsibility will definitely affect the results.
programmablelogic control systems are a rational augmentation of the potentials of electronic control and instrumentation arrangements. Complex safety-orientated and control functions can be cost-effectively and reli...
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programmablelogic control systems are a rational augmentation of the potentials of electronic control and instrumentation arrangements. Complex safety-orientated and control functions can be cost-effectively and reliably combined in a single PLC installation, without impairing operability and flexibility, via the addition of a number of individual components of a standard PLC system. The following article describes the practical use of error-proof control in twelve aluminium melting furnaces at TRIMET ALUMINIUM AG, Essen, Germany, in the context of modernization of the heating system, examining the benefits and disadvantages resulting from installation.
This article presents a process of converting the ladder diagram (LD) into the Petri net (PN) by analysing the attributes of the LD program and the characteristics of the programmablelogic controller (PLC) operation....
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This article presents a process of converting the ladder diagram (LD) into the Petri net (PN) by analysing the attributes of the LD program and the characteristics of the programmablelogic controller (PLC) operation. It also presents a new representative conversion method of obtaining a PN graph from an LD program. It is mainly developed to equip LD programs with the formal analysis capability normally available in the Petri net theory. In order to represent the PLC operations with the PN graph, the concepts of preservation arc, buffer place, and reset arc are introduced, and the conversion table that converts the core LD functions into the PN graph is constructed. In order to analyse mathematically the converted PN, the augmented Petri net state equation is created using firing condition function. The process of a material transport car (MTC) is used as an example to demonstrate the validity of the presented PN. The simulation results for the process of the MTC demonstrate that the presented PN is a valid approach to represent PLC programs.
The use of programmablelogic devices (PLD) to achieve greater system-level integration with the ability to implement networking functions and memory blocks was presented. The approach extended the capability to use t...
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The use of programmablelogic devices (PLD) to achieve greater system-level integration with the ability to implement networking functions and memory blocks was presented. The approach extended the capability to use the communication link to transmit the configuration data to update the PLD remotely. The system containing a PLD with an embedded processor core to support the Transmission Control Protocol (TCP)/Internet Protocol (IP) was also discussed. It was found that the ability to browse the PLD made revision control simpler by making information about the system easily accessible.
This study describes a system that uses the programmablelogic Controller (PLC) to control the motion of a two-axis sun-tracking surfaces. The present study was conducted to monitor the performance of system and measu...
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programmablecontrollers have become the industry's automation workhorses over the past 25 years, but most rely on unique programming languages. There are several problems this situation poses: the difficulty of f...
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programmablecontrollers have become the industry's automation workhorses over the past 25 years, but most rely on unique programming languages. There are several problems this situation poses: the difficulty of finding personnel that are `fluent' in multiple programmable controller programming languages;the time and cost involved in training them;and delays and problems caused by non-intuitive, difficult-to-debug programming languages. These are the problems that the International Electrochemical Commission (IEC) began tackling in the 1980s. The result is the IEC 61131-3 standards which create a level of commonality in the programming of industrial controllers.
The article takes as a starting point the consolidated necessity to verify, in quantitative terms, the reliability and safety levels characteristic of the programmablelogic central devices. An original methodology fo...
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The article takes as a starting point the consolidated necessity to verify, in quantitative terms, the reliability and safety levels characteristic of the programmablelogic central devices. An original methodology for the analysis of the above-mentioned characteristics in here illustrated;these properties are guaranteed in a strongly innovative way in comparison with the traditional systems. The article finally presents the results of a compared experimental application of this methodology to a programmablelogic central device and a relay apparatus.
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