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CHAPTER - INTRODUCTION TO PLCS. 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.
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CHAPTER - INTRODUCTION TO PLCS 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.
PLC Origin - Developed to replace relays in the late 1960s - Costs dropped and became popular by 1980s - Now used in many industrial designs
Relays and Schematic Symbols
Logical Control with Relays
Relay Logic In a PLC
Sample Problem: 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.