1 / 17

Programmable Logic Controller

Programmable Logic Controller. Chris Egbert Dec 1, 2008. Current State. A PLC is a small, self-contained digital computer Real time (output of the PLC is produced within a specific time bound relative to input data) Encased in protective housing to allay extreme environmental conditions

moeshe
Télécharger la présentation

Programmable Logic Controller

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Programmable Logic Controller Chris Egbert Dec 1, 2008

  2. Current State • A PLC is a small, self-contained digital computer • Real time (output of the PLC is produced within a specific time bound relative to input data) • Encased in protective housing to allay extreme environmental conditions • Have multiple ports for inputs and outputs (more ports = greater cost) • Connect to sensors, actuators, and other output devices

  3. Current State (continued) • May come in a modular form, such that additional I/O modules may be attached • Programmed directly through the PLC via buttons and lights, text displays, GUIs, or through a connected PC with appropriate software • Utilize networks for communication

  4. Where Used • Automation processes • Machinery on factory lines • Machining, electronics assembly, etc • Control of amusement park rides • Control of lighting fixtures • Interpretation of any type of sensor input

  5. Uses • Who: • Automated factories • Amusement parks • Any type of control system (could be used for a small device that responds to inputs) • What for: • Factory control (machines, conveyors, storage retrieval, etc) • Device response control • Force regulation on park rides • Many more

  6. Uses (continued) • When: • Whenever automation is required or human skill is not great enough to operate a machine • Whenever great precision is required • Under difficult environmental circumstances

  7. Costs • ~ $50 to $5,000 • Cost depends on the number and type of inputs and outputs, PLC processor speed, modularity of the PLC • Additional costs for additional I/O modules • Economic for situations in which production quantities are not very large as to allow a custom-designed control

  8. Supporting Technology • Communications • RS-232, RS-485, Ethernet, coaxial • Personal Computer for software editing • Programming Languages: • FBD (Function block diagram) • LD (Ladder diagram) • ST (Structured text, similar to the Pascal programming language) • IL (Instruction list, similar to assembly language) • SFC (Sequential function chart) • Adequate Sensors

  9. References • http://www.allaboutcircuits.com/vol_4/chpt_6/6.html • http://www.omron.com/products/indu.html • http://www.eod.gvsu.edu/~jackh/books/plcs/chapters/plc_intro.pdf • http://www.jlab.org/accel/ssg/Pss/plc.pdf • http://www.eod.gvsu.edu/~jackh/books/plcs/html/plcs.html#pgfId-864358

  10. Application Rules and Limitations • Useful in situations that require output responses to given inputs • Can only respond as fast as input and output devices can send and receive data • Though rugged, still limited by operating environment (i.e. 0 to 50 deg C, 10-90% humidity, 2000m or less altitude, etc)

  11. Vendors

  12. Standards • IEC 61131-3 • Defines 5 standards-based programming languages (listed earlier)

  13. Technical Paper • Title: • Multi-axes sun-tracking system with PLC control for photovoltaic panels in Turkey. • Authors: • Sungur, Cemil1 • Source: • Renewable Energy: An International Journal; Apr2009, Vol. 34 Issue 4, p1119-1125, 7p • A solar panel, attached to an electromechanical system and controlled by a PLC, is oriented to follow the sun’s position over a year so as to attain greatest solar energy input

  14. Integration • Principles of automation are based upon control systems • Automation breaks down if it cannot respond to variation, which is unavoidable • PLC’s act as the brains of the control system, interpreting real time data to alter the way the system operates

  15. Video • http://video.google.com/videosearch?q=PLC&emb=0&aq=f#q=christmas%20light%20music&emb=0

  16. Class Application • A device must determine temperature, speed, acceleration, and pressure. The device must then take this data and adjust to follow a user defined speed and acceleration (through the use of 2 stepper motors). If a PLC were used to control this system, how many inputs and outputs would it need?

  17. Summary • Modern automation is built upon the backs of PLC’s • PLC’s are highly customizable and may be altered to achieve a variety of tasks • PLC’s are an inexpensive alternative to highly specialized control systems • PLC’s require user defined programming in order to properly adjust for given inputs • As processing capability has increased with time, so too has the ability of PLC’s to perform an even wider range of tasks • A PLC may only be as fast and accurate as the sensor inputs

More Related