PLC
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Programmable logic controllers (PLCs) are digital electronic devices used to automate industrial processes. A PLC consists of a central processing unit, input/output modules, and a programming device. PLCs scan their program continuously and cyclically to monitor inputs and control outputs. They are programmed using ladder logic to perform functions like timing, counting, and controlling relays. PLCs are used widely in applications like process control, machinery control, and some CNC machine functions. Factors like the number of I/O points, memory, and scan time are considered when selecting a suitable PLC for an application.
PLC
- 2. Organization of the Presentation Introduction Components of PLC PLC Functioning PLC Programming Example Problems Applications PLC Selection
- 3. Introduction
- 4. PLC Defined Programmable Logic Controller (PLC) is a solid state device designed to perform logic functions. Essentially PLC is an assembly of solid state digital electronic elements designed to make logical decisions and provide outputs
- 5. Why PLC Relay based Process or Machine Control is expensive and Rigid Need for programmable and reconfigurable control Move towards Flexible Automation
- 7. Areas of Application Process control Control of Machinery Control of Equipments Certain Aspects of Control in CNC machines and Machining Centers
- 9. PLC Components Any PLC Has 1. A Central Processing Unit (CPU) Microprocessor based system 2. Input / Output Section (I/O Section) Digital and analog I/O s 3. Programming Device Usually a Computer
- 10. PLC Components
- 11. PLC Functioning
- 12. PLC’s Perform Scans Sequentially and Cyclically
- 13. Typical PLC Scan Sequence
- 14. PLC programming
- 15. Typical Inputs and their Representation
- 20. An Electro Mechanical Relay
- 21. Typical Outputs and Their Representation
- 22. Timers On Delay Timers Off delay timers Retentive Timers
- 23. Counters Up Counters Down Counters Up Down Counters
- 24. Relays Internal Relays External Relays Retentive Relays
- 25. Example Programs
- 26. Design a Control Program for a Water Pump Motor
- 27. Product in Position (LS1 Close) Start button on. Conveyer moves product to A (Limit switch LS1 returns to normal) Conveyer moves the Product to A and stops Distance to A counted by encoder (8 Pulses) Waits at A for 10 s Moves again to LS2 and stops Emergency stop Emergency stop resets counter and timer
- 29. Applications
- 30. Process Control Electroplating Heat Treatment Powder Coating Chemical Processing Refineries Control of Hydraulic and Pneumatic Circuits
- 31. Control of Machinery and Equipment Control of Material Handling Equipments like Conveyer Belts Control of Flexible, Automated Assembly Lines Control of Special Purpose Machines like Bottling Machine etc.
- 32. CNC Machines velocity, displacement and position control is being carried out by exclusive controllers (Hardware interpolators, Closed Loop Controllers etc..) Mostly all ‘M’ codes are transferred to PLC Control PLC Provides one more level of Protection in CNC Machines
- 33. Machining Centers Automatic Tool Changers Automatic Pallet Changers Overall system protection
- 34. PLC Selection
- 35. Criteria for Selecting PLC Number of logical inputs and outputs. Memory Number of special I/O modules Scan Time Communications Software
- 37. Commercial PLC Manufacturers Omron Electronics Inc. Allen Bradley Aromat GE-Fanuc IDEC Keyence Mitsubishi Modicon Omron Automation Direct Siemens Toshiba
- 38. PLC Manufacturers Websites Aromat http://www. aromat .com Keyence http://www. keyence .com/ plc /start. htm Toshiba http://www. toshiba .com.au/ plc /index.html
- 39. Some Interesting PLC Websites http://claymore.gvsu.edu/~jackh/books/plcs/ http://www.plcs.net http://www.geindustrial.com/cwc/solutions ?
- 40. Reference Programmable Logic Controllers by Frank D Petruzella, McGraw – Hill Books Companey, 1989.
- 42. Thank You