1. Advantages of PLCs Cost effective for controlling complex systems. Flexible and can be reapplied to control other systems quickly and easily. Computational abilities allow more sophisticated control. Trouble shooting aids make programming easier and reduce downtime. Reliable components make these likely to operate for years before failure. CHAPTER - INTRODUCTION TO PLCS

2. PLC Origin - Developed to replace relays in the late 1960s - Costs dropped and became popular by 1980s - Now used in many industrial designs

3. Relays and Schematic Symbols

4. Logical Control with Relays

5. Relay Logic In a PLC

6. Reading Ladder Logic

7. A Ladder Logic Example

8. Mnemonics

9. SFCs

10. Structured Text

11. PLC in a Control Loop

12. The Four Stages of a PLC Scan

13. Ladder Logic Inputs

14. Ladder Logic Outputs

15. Try to develop (without looking at the solution) a relay based controller that will allow three switches in a room to control a single light. Sample Problem: