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Programmable Logic Controller (PLC)

Programmable Logic Controller (PLC). Brian Caldwell Michael Davis November 28 th , 2007. Definition Dedicated computer for rapid processing of simple logic instructions in a defined time.

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Programmable Logic Controller (PLC)

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  1. Programmable Logic Controller(PLC) Brian Caldwell Michael Davis November 28th, 2007

  2. Definition • Dedicated computer for rapid processing of simple logic instructions in a defined time. • A solid state control system with a user programmable memory that can read input conditions and set output conditions to control a machine or process.

  3. Where are they Used? PLC’s are widely available and used in several, in fact almost all automated processes. • Aerospace • Automotive Industry • Entertainment • Petroleum Industry • Food, Beverage, and Packaging • AND EVERYTHING IN-BETWEEN

  4. Required Technology Here is a simplistic view of a PLC system which consists of three main components: an Input/Output Section, the Processor and a Programming Unit. Machine or Process Programmable Logic Controller Output Devices Input Devices Programming Unit

  5. Costs • The most simple and basic PLC will cost around $50 • The most advanced and sophisticated PLC run around $10,000 Http://web4.automationdirect.com/adc/overview/Catalog

  6. LADDER LOGIC • Ladder logic is really just a symbolic representation of an electrical circuit. Symbols were chosen that actually look similar to schematic symbols of electrical devices. • Three broad Categories • Contacts (Inputs) • Coils (Outputs) • Special Function blocks (timers, counters…etc.)

  7. Sample Problem In the figure, will the power on the first wrung normally be on or off? And for the second wrung?

  8. Standards & limitations • Standards • Work in severe conditions (dust, moisture, heat, cold, etc) • Have the facility for extensive input/output (I/O) arrangements • Uninterrupted production • Long life of equipment • Limitations • Limited by the number of input/output ports • More sophisticated = harder to program

  9. Vendors • Allen-Bradley • Mitsubishi Electric • ABB Ltd. • Honeywell • Siemens • Modicon • Omron • General Electric • Square-D • Panasonic

  10. Video Clip • http://video.google.com/videosearch?q=plc+application+duration%3Ashort&num=10&so=0&start=0

  11. REFERENCES • Dr. Red- Professor Brigham Young University • http://www.eod.gvsu.edu/~jackh/books/plcs/chapters/plc_intro.pdf • http://en.wikipedia.org/wiki/Programmable_logic_controller • http://www.tri-plc.com/applications/m-plc2.htm • http://www.tri-plc.com/applications.htm • http://etidweb.tamu.edu/hsieh/LadderLogic/Symbols_vers5.5.html • http://web4.automationdirect.com/adc/Overview/Catalog/PLC_Hardware

  12. Summary • PLC are used Everywhere • Controls processes with inputs and outputs • Cost range for $50 - $10,000 • Ladder logic is commonly used to program PLC’s • Built to perform in severe conditions

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