This paper describes how a system, consisting of a discrete controller (e.g. a PLC) that controls a physical plant/process, can be formally verified. The physical process is assumed to be modeled using Sensor Graphs, ...
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ISBN:
(纸本)9781424445783
This paper describes how a system, consisting of a discrete controller (e.g. a PLC) that controls a physical plant/process, can be formally verified. The physical process is assumed to be modeled using Sensor Graphs, a discrete event modeling language directed at physical systems with binary and identity sensors (e.g. RFID). The formal and graphical syntaxes of Sensor Graphs are presented and exemplified. The "semitimed" semantics is defined considering a process model together with a controller model, represented as a discrete state equation. Finally, it is shown how requirements on the closed. loop system, represented by a Sensor Graph and a controller model, can be verified using the model checker Cadence SMV.
Environmental issues are getting widespread international attention. The damage to the plant is immeasurable, too. For monitoring the vegetation conditions, a non-destructive, simplified and low-cost chlorophyll fluor...
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ISBN:
(纸本)9781424429752
Environmental issues are getting widespread international attention. The damage to the plant is immeasurable, too. For monitoring the vegetation conditions, a non-destructive, simplified and low-cost chlorophyll fluorometer was developed. Pulse amplification modulation method and control using programmable logic controller has been employed for that purpose. By measuring the fluorescence from spinach leaf, the performance of the system was checked. It was found that the system was provided empirical data to support theory.
programmable logic controller (PLC) plays a more and more important role in the field of industry. To deal with the heterogeneity of manufacture-dependent programming languages, IEC 61131-3 international standard has ...
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ISBN:
(纸本)9780769535838
programmable logic controller (PLC) plays a more and more important role in the field of industry. To deal with the heterogeneity of manufacture-dependent programming languages, IEC 61131-3 international standard has promoted the PLC openness to developing. In this paper, we present a proposal to implement the IEC 61131-3 standard in a PLC virtual machine (VM), which is a new kind of high-level language VM and takes Instruction List (IL) as the intermediate code. We discuss the syntax and semantics of IL, and show the design architecture for the emulation engine using both interpretation and translation methods. The PLC VM enables developers to rapidly porting an IEC-61131-3 application onto different platforms. We have implemented the PLC VM on a C51 based embedded PLC platform.
This paper introduces Whimori CDK, an integrated development environment for PLC control programs based on IEC 61131-3 standard and TC6 XML schema. Whimori CDK consists of project manifest editor, LD graphic editor, L...
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ISBN:
(纸本)9780769535388
This paper introduces Whimori CDK, an integrated development environment for PLC control programs based on IEC 61131-3 standard and TC6 XML schema. Whimori CDK consists of project manifest editor, LD graphic editor, LD-to-IL translator, IL runtime, LD-to-SMV translator, SMV model checker etc. The components of Whimori are portable and independent since they have been developed as Eclipse plug-ins. Particularly LD-to-IL translator, LD-to-SMV translator and IL runtime are designed to be based on forma( semantics, implemented in Ocaml., and more reliable than other systems. This paper describes the overall structure of Whimori CDK and the features of graphic user interfaces and interior components.
The paper presents modified idea of program execution in PLCs. Instead of serial cyclic execution of control program event-driven execution is proposed. Suggested approach to program execution allows for selective exe...
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The paper presents modified idea of program execution in PLCs. Instead of serial cyclic execution of control program event-driven execution is proposed. Suggested approach to program execution allows for selective execution of program parts or tasks provided calculation condition for this part has changed since last time. There only these blocks from entire program are executed whose variables have changed since last calculation. Proposed method can be implemented as software modification or as hardware accelerated solution. The most important part of the idea is task or subprogram triggering condition computation. Methods of program optimization are discussed. In order to determine program blocks that require recalculation in current program scan execution specific hardware support is planned to be researched. Memory content change detection unit allows to determine changes in memory content since last program block execution.
Abstract This paper makes two key contributions. First there is a definition and implementation of a novel auto-tuned predictive controller. The key novelty is that the modelling is based on relatively crude but pragm...
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Abstract This paper makes two key contributions. First there is a definition and implementation of a novel auto-tuned predictive controller. The key novelty is that the modelling is based on relatively crude but pragmatic plant information. Secondly, the paper tackles the issue of availability of predictive control for low level control loops. Hence the paper describes how the controller is embedded in an industrial programmable logic controller (PLC) using the IEC 1131.1 programming standard. Laboratory experiment tests were carried out in two bench-scale laboratory systems to prove the effectiveness of the combined algorithm and hardware solution. For completeness, the results are compared with a commercial PID controller (also embedded in the PLC) using the most up to date auto-tuning rules.
The dual core bit-byte CPU must be equipped with properly designed circuits, providing interface between the two processor units, and making it possible to exploit all its advantages like versatility of the byte unit ...
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The dual core bit-byte CPU must be equipped with properly designed circuits, providing interface between the two processor units, and making it possible to exploit all its advantages like versatility of the byte unit and speed of the bit unit. First of all, the interface circuits should be designed in such a way, that they don't disturb maximally parallel operation of the units, and that the CPU as a whole works in the same manner as in a standard PLC. The paper presents hardware solutions supporting effective operation of PLC CPU-s. Possibilities of solving problems concerning data exchange between a CPU and peripheral circuits were presented, with a special stress on timers and counters and also on data exchange between the bit unit and the byte unit. The objective of the proposed solutions is to decrease the time necessary for a CPL to access is peripheries.
programmable logic controller (PLC) characteristics for automatic dimensioning and allocation in process control. The automation of an industrial process is invariably faced with the decision of the optimal resources ...
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programmable logic controller (PLC) characteristics for automatic dimensioning and allocation in process control. The automation of an industrial process is invariably faced with the decision of the optimal resources for implementation. It is important to find a way of selecting the most efficient programmable logic controller that is suitable to facilitate a particular control process. Variables such as the number of inputs or outputs, program memory size, data memory size, auxiliary memory, timers and counters have to be given the requisite consideration. The method undertaken considers the use of ladder diagrams and XML in the process of modelling PLC characteristics which are organised in form of a database. Criteria for PLC selection are used to provide a list of PLCs or embedded controllers that best fits the control process envisioned.
Developing PLC software for modern machine tools is becoming more difficult because of the increasing functionality and resulting complexity. An approach for managing this is provided by the model-driven development o...
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Developing PLC software for modern machine tools is becoming more difficult because of the increasing functionality and resulting complexity. An approach for managing this is provided by the model-driven development of the control software. However, this innovative development method requires both a procedure that is adapted to the specific application domain and suitable modeling techniques. The article describes an approach appropriate for machine tools. The focus is on introducing the necessary description techniques and a methodology for their use in product development.
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.
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