PLC - Programmable Logic Control

1. PLC - Programmable Logic Control Jon Pruett December 1, 2008

2. Overview – Current State • Definition – dedicated computer for rapid processing of simple logic instructions in a defined time • Unlike general-purpose computers, PLC’s are designed to handle multiple input and output arrangements, and are resistant to vibration and impact

3. Where Used? • Mostly used in automated processes • Control of machinery on factory assembly lines • Control of amusement rides • Control of lighting fixtures

4. Who Uses and When? • Any industry that utilizes automation, or any machine/device that uses automatic control. • Example: The 1st PLC created was made for GM Hydramatic (Automatic Transition Division for General Motors) • 2 Main Approaches • Logic Control • Closed-loop method • Uses conditions and events to signal completion of an event, then triggers some reactive event • Asynchronous method • Sequencing • Open-loop method • Uses timers to trigger completion and beginning of steps • Synchronous method

5. Cost • As low as $60 • Up to $400 • Depends on size, speed, input/output arrangement

6. Supporting Technology? • How complicated is the Program? • What do you want the PLC to control? • Basic Components of PLC: Processor unit (CPU), Memory, Input/Output, Power supply unit, Programming device • Machine Vision commonly used

7. References • Automation Book • Dr. Red slides • PLC Manual (http://www.plcmanual.com/plc-hardware) • Wikipedia (www.wikipedia.com) • AutomationDirect (www.AutomationDirect.com/plcs) • FactoryMation (www.factorymation.com) • Triangle Research (http://www.tri-plc.com/products.htm) • PLC’s.net (http://www.plcs.net/chapters/links.htm) • http://instrumentation.co.za/article.aspx?pklArticleId=4564&pklCategoryId=67 • Google Scholar (www.byu.edu)

8. Application Rules, Limitations?

9. Vendors

10. Existing and Evolving Standards • The primary standard available for programmable logic controller (PLC) programming is defined in IEC 61131. This standard has been embraced by many other international standards organisations. For example, the American National Electrical Manufacturers Association (NEMA) standard IA 2.3-2005 is based on IEC 61131-3 as is the British Standard BS EN 61131-3. More industries, people are beginning to incorporate PLC’s • Organizations are trying to standardize PLC programming to facilitate training by allowing users to learn on one model of hardware, but apply common techniques to all compatible hardware

11. Technical Paper

12. How it Integrates • Excellent proof of Planning out the program and diagrams of PLC • Models of systems (if accurate) save time and money

13. Kewl PLC Video

14. Class Application • Make a simple ladder logic diagram for the garage PLC solution.

15. Summary • Overview • A dedicated computer for rapid processing of simple logic instructions in a defined time • Used in automated processes (rollercoaster) • Used a lot in automated industry • Logic control and sequencing approaches • Cost: $60-$400 • Machine vision commonly used as supporting technology • Dr. Red = Good reference • Use in Industry • Applications include simple and, or, not diagrams/programs • Few limitations for its function • Main known vendors: Honeywell, Rockwell, Sharp, Unitronics • Standards: IEC 61131. Trying to standardize PLC programs • Application examples • Modeling Programs and Diagnosable functions for PLCs • Useful in planning and determining structure and diagram • Parking garage video • Design your own street light system • End of the line

16. “Applause” • Questions?