programmable logic controller
- 1. WELCOME
- 2. Programmable Logic Controllers (PLC's) A.VETRI MANI Nanotechnology 117012305044 TECHNICAL COMMUNICATION
- 3. The Need for PLCs • Hardwired panels were very time consuming to wire, debug and change. • GM identified the following requirements for computer controllers to replace hardwired panels. – Solid-state not mechanical – Easy to modify input and output devices – Easily programmed and maintained by plant electricians – Be able to function in an industrial environment
- 4. The First Programmable Logic Controllers (PLCs) • Introduced in the late 1960’s • Developed to offer the same functionality as the existing relay logic systems • Programmable, reusable and reliable – Could start in seconds – Used Ladder Logic for programming
- 5. Programmable Logic Controller • A programmable logic controller (PLC) is a specialized computer used to control machines and process. • It uses a programmable memory to store instructions and specific functions that include On/Off control, timing, counting, sequencing, arithmetic, and data handling
- 6. Advantages • Flexible • Faster response time • Less and simpler wiring • Solid-state - no moving parts • Modular design - easy to repair and expand
- 8. PLC System
- 9. PC Based Control Systems Advantages : Lower initial cost Less proprietary hardware and software required Straightforward data exchange with other systems Speedy information processing Easy customization
- 10. PLC Size Classification Criteria Number of inputs and outputs (I/O count) Cost Physical size Nano PLC Smallest sized PLC Handles up to 16 I/O points Micro PLC - Handles up to 32 I/O points
- 11. PLC Size Classification Allen-Bradley SLC-500 Family - Handles up to 960 I/O points Allen-Bradley PLC-5 Family Handles several thousand I/O points