In this paper, we propose a dedicated architecture for a ladder solving processor (LSP) for programmable controllers. For this purpose, a mathematical representation of the ladder language is suggested for the first t...
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In this paper, we propose a dedicated architecture for a ladder solving processor (LSP) for programmable controllers. For this purpose, a mathematical representation of the ladder language is suggested for the first time and algorithms for solving this ladder language are presented using abstract notation. The proposed LSP is designed to be suitable for the above algorithm, and contains a logic solving unit, column execution unit and box solving unit, which employ array, pipeline and microprogrammed architectures, respectively, in order to enhance the processing speed. The performance of the proposed architecture is demonstrated by an experimental prototype of the LSP. It is also shown by computer simulation that, under reasonable assumptions, the proposed LSP can process a pure logic instruction group at 45.5 MIPS using eight cells. In the case of a ladder program, a quarter of which is a box instruction group, the LSP can process at a rate of 0.27 ms kstep-1 using a single cell architecture, and at a rate of 0.18 ms kstep-1 using four cells. This is much faster than for existing programmable controllers.
Cleaning-in-Place (CIP) is a crucial part to be automated in batch process industries. In many Process industries after completion of a batch, the equipment cleaning is done by using CIP process. There are many method...
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ISBN:
(纸本)9781509020805
Cleaning-in-Place (CIP) is a crucial part to be automated in batch process industries. In many Process industries after completion of a batch, the equipment cleaning is done by using CIP process. There are many methods used for cleaning the industrial equipments like tanks in food and pharmaceutical industries, such as 3-step, 5-step and 7-step CIP. In any industry, once the batch product is manufactured, the equipments used for manufacturing should be cleaned to have hygienic products. The tanks, pipes are cleaned with different chemical solutions, such as caustic, acids, enzymes etc. To have an economical production, sometimes the solutions are recovered and reused. This paper is primarily addicted with a scene to provide combination of the concepts and application of automation of CIP in the process industries like food, dairy, beverage and pharmaceutical verticals. Proposed work for dairy industries contains CIP defined for cleaning and sterilizing of tanks, valves, and pipes with the help of acid, lye and consequent sterilization with high energy efficiency.
The draft IEC standard for programmable controllers contains the elements necessary for the introduction of modern programming practices for the control of processes and machines, while retaining the ease of use of tr...
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Strong timing requirements and complex interactions with controlled elements complicate the design and validation of software controllers. Different techniques have been proposed to cope with these problems during the...
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ISBN:
(纸本)0780365836
Strong timing requirements and complex interactions with controlled elements complicate the design and validation of software controllers. Different techniques have been proposed to cope with these problems during the different development steps: for example, differential equations for modeling controlled elements, the IEC 1131-3 notations for designing the software controller, and formal models for validating the design, but no definitive solutions have been proposed yet. This paper describes PLCTOOLs;a toolbox that exploits all aforementioned techniques to supply an integrated environment for the design, formal validation, and automatic code generation of software controllers.
The draft IEC standard for programmable controllers contains the elements necessary for the introduction of modern programming practices for the control of processes and machines, while retaining the ease of use of tr...
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The draft IEC standard for programmable controllers contains the elements necessary for the introduction of modern programming practices for the control of processes and machines, while retaining the ease of use of traditional graphical programming languages. Widespread acceptance of the standard will lead to increased readability, reliability, and maintainability of control programs. Advanced graphic programming environments and new programmable controller architectures will be required to make optimal use of the new approaches which will be made possible when the standard is finally adopted.
Real-time systems are systems which interact permanently with their environment by receiving external informations and producing output commands on it. They are commonly met in factories for the control of industrial ...
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Real-time systems are systems which interact permanently with their environment by receiving external informations and producing output commands on it. They are commonly met in factories for the control of industrial processes. In this case, they are often implemented with programmable controllers (PC). The GRAFCET language, which is derived from Petri-Nets, is often used for programming such PC. Unfortunately, it is not based on a single semantics, which complicates programs verification, programs exchange and programs simulation. We have expressed its semantics with synchronous processes, implemented them with the synchronous language SIGNAL and investigated methods to make proofs on it.
A method for designing ladder diagrams for sequencing tasks is described. it is systematic, fast, and simple to apply. The method is applicable to both programmable controllers and hard-wired relay circuits. While it ...
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A method for designing ladder diagrams for sequencing tasks is described. it is systematic, fast, and simple to apply. The method is applicable to both programmable controllers and hard-wired relay circuits. While it does not minimize the number of required relays, this should be no problem when working with programmable controllers. The method is based on the idea of dividing the required sequence into groups according to a simple rule. These groups are then encoded using the "one-hot" code, with each group assigned one relay set up to operate as RS-flip-flop. The various operations belonging to a particular group result each in a single ladder-diagram line. The method can also be adapted to systems with multiple-path programs having one or more random inputs. This is of special importance when using simple, low-cost programmable controllers, which usually do not provide conditional jumps. Four examples of such multi-path programs are presented: Two or more simultaneous parallel paths; two or more alternative parallel paths; option of by-passing certain steps; and option of repeating certain steps. The method has been used successfully in an instructional automation laboratory at the author's institute.
programmable network interfaces can provide network servers with a flexible interface to high-bandwidth Ethernet links, but they face critical software and architectural challenges. This article explores architectural...
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programmable network interfaces can provide network servers with a flexible interface to high-bandwidth Ethernet links, but they face critical software and architectural challenges. This article explores architectural and software suport for an programmable 10 Gigabit Ethernet controller. The design is then extended to support a self-securing Gigabit Ethernet controller that performs intrusion detection on all network data frames. Both raw performance and security require highbitrate frame data transfer, low-latency metadata access, and intensive computational capacity while still operating under the area, cost, and power bud et of a peripheral device. These goals are achieved using a combination of parallel lightweight processing cores, an explicitly -partitioned memory system, and dedicated hardware assists. The firmware on the network interface is designed to utilize these resources efficiently by exploiting frame-level, flow-level, and task-level concurrency.
programmable logic controllers (PLCs) are widely used in embedded systems. Timers play a pivotal role in PLC real-time applications. The formalisation of timers is of great importance. The study presents a formalisati...
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programmable logic controllers (PLCs) are widely used in embedded systems. Timers play a pivotal role in PLC real-time applications. The formalisation of timers is of great importance. The study presents a formalisation of PLC timers in the theorem proving system Coq, in which the behaviours of timers are characterised by a set of axioms at an abstract level. The authors discuss how to model timers at a proper and sound abstract level. PLC programs with timers are modelled. As a case study, a quiz machine problem with a timer is investigated. This work demonstrates the complexity of formal timer modelling.
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