The first programmable logic controllers (PLCs) emerged in the 1970s. These PLCs offered the advantages of relay ladder logic emulation, and direct connectivity to data logging and HMI screens. However, unlike the rel...
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The first programmable logic controllers (PLCs) emerged in the 1970s. These PLCs offered the advantages of relay ladder logic emulation, and direct connectivity to data logging and HMI screens. However, unlike the relay circuits they emulated, PLCs outputs were roughly equally likely to fail on as off. With their poor performance, organizations abandoned the use of analogue PLCs. In the mid 1980s, the second generation of PLCs were introduced. It became possible to maintain both Dual Leg 2oo2 voting Basic Process Control Systems (BPCs) logic solvers and 2oo3 voting Safety Instrumented System (SIS) logic solvers in uninterrupted service virtually independently. At the same time, testing and certification have been increasingly delegated to third party agencies. With the increasing regulations of plants by government authorities, assuring fail safe operation of PLCs became more important. This brought about the development of IEC61508 standard for functional safety. The standard has seven parts. PLC solver manufacturers need to meet the requirements of Part 2 (hardware) and Part 3 (software) to successfully enter the market.
As circuit sizes grow ever larger, test data volume and test application time grow unwieldy even in the very efficient scan based designs. Adaptive scan architecture of Design for Test (DFT) technique is used to reduc...
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A programmable digital clock generator that produces a wide range of clock frequencies with fine resolution is described. The clock generator consists of a noise-shaping control loop and a number-controlled oscillator...
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A programmable digital clock generator that produces a wide range of clock frequencies with fine resolution is described. The clock generator consists of a noise-shaping control loop and a number-controlled oscillator. The generated clock has a time-varying period. When this clock is used as the sampling clock in a switched-capacitor filter (SCF) to set its frequency response, the time-varying period causes nonuniform sampling, which is acceptable under certain conditions that are described. Measured performance of a 2-μm CMOS implementation of the clock generator is presented. Also, measured data for the clock generator driving two SCF's are reported.
The contribution deals with an implementation of discrete control logic for a modular production line, with two main objectives pursued. Firstly, the basic ideas of PackML standard should be implemented, in particular...
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The contribution deals with an implementation of discrete control logic for a modular production line, with two main objectives pursued. Firstly, the basic ideas of PackML standard should be implemented, in particular the behaviour of the machine from the operational state viewpoint, and secondly, the implementation should be based on low-end programmable logic controllers, with limitations on the available memory and processing speed. The paper presents a general idea of the implementation with discussion of its relation to PackML standard, and provides relevant details of the implementation case study on a laboratory scale modular production system.
Alzheimer's Disease (AD) is an irreversible, degenerative condition that, while incurable, can have its progression slowed or impeded. While there are numerous methods utilizing neural networks for AD detection, t...
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Hitachi has developed several new nodules for its small-end programmablelogic controller (PLC) of the EH-150 series. The modules have a processing speed of basic commands, programming-memory capacity, and improved co...
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Hitachi has developed several new nodules for its small-end programmablelogic controller (PLC) of the EH-150 series. The modules have a processing speed of basic commands, programming-memory capacity, and improved communication functionality.
In 1992, NDBTohoku introduced the Voith shoepress due to raise dehydration up at press part for the first time in Japan. This press was remodel from import facility, and the control logic had not established. Therefor...
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In 1992, NDBTohoku introduced the Voith shoepress due to raise dehydration up at press part for the first time in Japan. This press was remodel from import facility, and the control logic had not established. Therefore we constructed the control logic with manufacturer (IHI). But. we complained about analyze the factor of sequence delay, because of complicate systems and less operation experience. For speed up of the failure factor analysis, we observed this shoepress control logic in 2003, using by PLC observation monitor.
Wisconsin Public Service Corp. (WPSC), a wholly owned subsidiary of Green Bay, Wis.-based WPS Resources (WPSR), looked at control modernization for its Weston 1 and Weston 2 units with the objective of leveraging the ...
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Wisconsin Public Service Corp. (WPSC), a wholly owned subsidiary of Green Bay, Wis.-based WPS Resources (WPSR), looked at control modernization for its Weston 1 and Weston 2 units with the objective of leveraging the information management benefits of the personal computers (PC) world. They chose to stretch the envelope on PC/programmable logic controllers (PLC) systems by using the just-released Windows NT version 3.5 as the basis for a fast track and somewhat risky upgrade. The resulting system produced faster ramp rates, combustion and burner control improvements, and better overall operator capability that generated both expected savings and more reliable power.
The significance of programmable automation controller (PAC) over programmable logic controllers (PLC) is discussed. The PAC controllers combines the features of PC, including processor, RAM and software, with the rel...
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The significance of programmable automation controller (PAC) over programmable logic controllers (PLC) is discussed. The PAC controllers combines the features of PC, including processor, RAM and software, with the reliability rugedness and distributed nature of PLC. It uses commercial-off-the-shell (COTS) technologies suited for industrial environment, ensuring scalability, easy maintenance and lower downtime. PXI is a fast growing PAC platform. It offers cost savings, advanced control, security, real-time analysis, web connectivity, computing power, scalability and several other features that makes it better than PLC.
In the field of automation technology education, the primary emphasis is on instructing students in the use of programmable logic controllers (PLCs). Practical training for beginners includes sessions on wiring and pr...
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