The modern stage suspended boom system is automatically controlled by PLC (programmable logic controller), and represents a typical hybrid behavior. It is an important family of stage control machinery systems. This p...
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The modern stage suspended boom system is automatically controlled by PLC (programmable logic controller), and represents a typical hybrid behavior. It is an important family of stage control machinery systems. This paper presents a formal approach to modeling the system behaviors of different scenes. The system is formally characterized and specified in a timed model. System properties are proved in the proof system of the extended duration calculus. The case study illustrates the feasibility of the proposed verification framework. (C) 2011 Elsevier Ltd. All rights reserved.
Voltage sag and short interruption lead to the tripping of sensitive equipment and cause the economic loss of the industry users. A programmable logic controller (PLC) is essential equipment used in the industrial pro...
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Voltage sag and short interruption lead to the tripping of sensitive equipment and cause the economic loss of the industry users. A programmable logic controller (PLC) is essential equipment used in the industrial process. However, there is no detailed understanding of the sensitivity of PLC under voltage sag and short interruption. The response characteristic of PLC under voltage sag is studied. This study proposes a new testing method, called the dichotomy test method (DTM) to do the test. This study builds the testing platform and tests the sensitivity of six PLCs from five famous PLC manufacturers. The testing considers the characteristics of voltage sag, including magnitude, duration, point-on-wave, phase-angle-jump, different supply voltage, slow recovery voltage sag, multiple voltage sags and so on. The tests prove that DTM has the advantage of accuracy, robustness and workload, compared with the traditional test method. The quantitative and qualitative response characteristics of PLC under voltage sag are obtained.
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.
In this work we propose an implementation of IEC 61131-3 programmable logic controller (PLC) software model based on ADA programming language. The guidelines for an IEC 61131-3 to ADA translator are shown. This transl...
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In this work we propose an implementation of IEC 61131-3 programmable logic controller (PLC) software model based on ADA programming language. The guidelines for an IEC 61131-3 to ADA translator are shown. This translator would allow obtaining executable code after compiling the ADA code. In this way, most error conditions that the standard foresees for PLC systems can be managed by the usual ADA compilers or the run-time environment, thus improving software quality. In addition, we show how to manage user- or system-defined error conditions in two ways: first, by proposing ADA-like exception statements in IEC languages;second, by showing an implementation of the error tasks that are explained in part 8 of IEC 61131 standard. Therefore, we conclude that ADA is a suitable target language for PLC. (c) 2006 Elsevier B.V. All rights reserved.
A integrated virtual learning system is being researched and developed to teach students about programmable logic controllers (PLCs). This system, called the Virtual PLC, incorporates intelligent tutoring system, simu...
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A integrated virtual learning system is being researched and developed to teach students about programmable logic controllers (PLCs). This system, called the Virtual PLC, incorporates intelligent tutoring system, simulation, and animation technologies. This article describes the development and evaluation of modules on PLC timer and counter instructions. These modules were first developed using an intelligent tutoring system (ITS) authoring tool and animation tools. After the concept was proved positively, a Web-based ITS was developed to incorporate both modules. The authoring tool-based ITS timer modules were evaluated with 90 undergraduate manufacturing engineering students in 2002. The Web-based ITS timer and counter modules were evaluated by 38 undergraduate students in 2003. In both cases, students made statistically significant learning gains as a result of taking the modules, and rated the modules positively in terms of ease of use and understanding, dear objectives, amount of interaction, ability to motivate, relevance, and pace.
This paper presents a fully automated programmable logic controller (PLC) based direct load control system. Unlike other existing systems, it gives the consumer the privilege to share in the load shedding policy. Afte...
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This paper presents a fully automated programmable logic controller (PLC) based direct load control system. Unlike other existing systems, it gives the consumer the privilege to share in the load shedding policy. After receiving the warning alarm from the PC at the utility control center, the consumer has the chance to switch off any desired load. If he does not act within a predefined period, the PLC will take the required action based on the scenario decided by the utility. Having the consumer decide his own priorities release the utility company from blind decisions. This is one of the most important contributions of the proposed system. Also the load restoration process is scheduled to avoid the creation of a new peak during re-energization. This is done using 48 built-in timers with an accuracy of less than one cycle (10 ms). The hardware at the customer side may be integrated with a digital energy meter to form a complete energy management system. (C) 1999 Elsevier Science S.A. All rights reserved.
The execution speed of a programmable logic controller (PLC) depends upon the number of analog and digital input it scans, complication in ladder diagram and the time to store the ladder diagram outputs in memory. Nex...
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The execution speed of a programmable logic controller (PLC) depends upon the number of analog and digital input it scans, complication in ladder diagram and the time to store the ladder diagram outputs in memory. Next to the ladder diagram, scanning of analog signals consume enough time as they have to be converted into digital. The two facts that limit the conversion speed is that the processor used for analog signal scanning can process only one channel at a time and the multichannel analog to digital converter (ADC) has digital output for only one channel. The hardware nature of field programmable gate array (FPGA) allows simultaneous conversion of all the analog signals into digital and storage of digital data in block RAM. The proposed design discusses the design of multichannel ADC using FPGA. The simulation result shows that the conversion time of 'n' channel ADC is 13.17 mu s. This increases the PLC execution speed. (C) 2014 Elsevier B.V. All rights reserved.
As programmable logic controllers (PLC) technology, programming languages and communication capabilities have advanced, PLCs offer many control devices to be attached directly to the PLC. For this reason PLC education...
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As programmable logic controllers (PLC) technology, programming languages and communication capabilities have advanced, PLCs offer many control devices to be attached directly to the PLC. For this reason PLC education became an important issue in many interdisciplinary engineering departments of the Universities. In this paper an automation set for the laboratory of PLC is developed which can be operated in various ways by programming a PLC as desired. The designed set also enables the students to understand the operation principle of an elevator. This developed educational laboratory set can be used as a practice for sensors and actuators, control systems and industrial automation courses. The laboratory tool also provides a method to improve learning outcomes, skills and the real-time experiences in engineering education such as electrical, electronics, mechatronics and control engineering.
programmable logic controllers (PLC) have been one of the most widely used controllers in industry. They have a graphical programming language interface resambling the relay panels which they are intended to replace s...
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programmable logic controllers (PLC) have been one of the most widely used controllers in industry. They have a graphical programming language interface resambling the relay panels which they are intended to replace so that the transition from relay panels might be swift and smooth. Although learning this programming language is easy, real life experiments are essential for students to gain greater understanding of the logic behind the language. However, it is generally too expensive to provide an experimental set-up for students to test their theoretical knowledge. For this reason, a conveyor and feeder system was developed as a low cost 3D printable design using a CAD program and implemented for use in a control laboratory. Using this conveyor set-up, students can experience how to program a practical example of a PLC devices used in industry together with an introduction to actuators and sensors. Reading actual sensors and using actuators via the inputs and outputs of a PLC to control a real life system will be far more effective than simulator alternatives.
This study describes the Virtual programmable logic controller (Virtual PLC), a web-based system for PLC education that consists of (1) educational simulations to help students visualize abstract concepts, practice pr...
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This study describes the Virtual programmable logic controller (Virtual PLC), a web-based system for PLC education that consists of (1) educational simulations to help students visualize abstract concepts, practice programming and device interfacing skills, and understand problem-solving processes;and (2) a simple intelligent tutoring system. Results from two preliminary evaluations are also presented. Index Terms-PLC, intelligent tutoring system, simulation, manufacturing engineering education. (c) 2005 Wiley Periodicals, Inc. Comput Appl Eng Educ 13: 266-279, 2005;Published online in Wiley InterScience (***. com);DOI 10.1002/cae.20052
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