نتایج جستجو برای: programmable logic controllers
تعداد نتایج: 205092 فیلتر نتایج به سال:
Input/Output is the mechanism through which Programmable Logic Controllers (PLCs) interact with and control the outside world. Particularly when employed in critical infrastructures, the I/O of PLCs has to be both reliable and secure. PLCs I/O like other embedded devices are controlled by a pin based approach. In this paper, we investigate the security implications of the PLC pin control system...
Fault diagnosis systems in electric sector companies require precision and flexibility properties in case of events. Currently, there are systems aimed at improving the diagnosis process through various methods and techniques, reducing response time to disturbances. However, few proposals unify graphical models of knowledge with process signals. These signals can be provided by devices such as ...
The rapid automation of automotive body assembly operations has resulted in a proliferation of the process steps to be monitored and displayed, thereby making the task of the worker more complex. The progression of assembly and associated machine cycling is controlled by programmable logic controllers whose states are displayed on control panels. The significance of the interface between a work...
A programmable logic controller (PC) carries out a control algorithm under violations of the ontological assumptions (VOA) when the plant does not meet one or more unstated but essential assumptions used in the design of the control algorithm. This paper presents a recovery technique based on the theory of Fuzzy State Fuzzy Output Finite State Machines (FSFO-FSM). The appeal of this approach is...
The application of Programmable Logic Controllers (PLCs) in safety critical systems demands a failure free behavior considering all possible scenarios. Due to the cost of software development a user program is often in use on different types of PLCs. But one open question is: Behaves the user program equivalent on all PLCs? We propose a framework suitable to prove the equivalence of a user prog...
High performance programmable logic controllers(PLCs) are time critical systems that require deadline-guaranteed response time. This paper describes a processor and network scheduling method for real-time PLCs supporting networkbased I/O systems and multi-tasking facilities. This enhances schedulability under the pre-de ned response time constraints, by adjusting the period as well as the relea...
Nowadays, most control systems are based on programmable logic controllers (PLCs) and on commercial programs, but the use of conventional PCs is becoming an increasing by popularity and competitive alternative. After an introduction that underlines the positive and negative aspects of both solutions, EtherCAT, a hard real-time industrial Ethernet protocol that allows the use of both conventiona...
In this work a set of tools is developed to convert programs for Programmable Logic Controllers (PLCs) into timed automata in order to facilitate the verification of such programs. The construction of the compilers is dicussed and some results are given for small PLC programs. Conclusions: The compilers produced in this work are able to perform the translations given in the figure below: il2i c...
Sequential function charts (SFCs) are defined as a modeling language in the IEC 1131-3 standard [1] and can be used to structure and drive programmable logic controllers (PLCs). It includes interesting concepts as hierarchy, history variables and priority. As the typical application area of this language is the control of industrial processes, it is obvious that safety and reliability is a cruc...
The hardware engineering efforts at the National Synchrotron Light Source facility are currently geared towards the use of programmable logic controllers (PLCs) for the control of machine hardware. The PLC provides a cost-effective solution combined with easy maintenance and upgrade. Modicon control products from Schneider Automation Inc. have been chosen since a wide range of PLC’s, inexpensiv...
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