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Programmable Logic Controllers (PLCs) - Coggle Diagram
Programmable Logic Controllers (PLCs)
Programmable Logic Controllers (PLCs)
1.2 Evolution of PLCs
Replacement for relay-based systems
Reduced hardwiring complexity
Adapted to changing industrial needs
1.3 Key Characteristics
High reliability
Immunity to noise & vibration
Designed for harsh environments
1.1 Definition of PLC
Operates in real-time environment
Designed for machine/process control
Industrial-grade digital computer
Advantages of PLCs over Relay Systems
2.2 Flexibility
Easy system upgrades
Software-based control logic
Program changes without rewiring
2.3 Cost Effectiveness
Reduced maintenance
Compact panel design
Lower installation cost
2.1 Increased Reliability
Reduced wiring errors
Consistent performance
Solid-state components
Basic Parts of a PLC
3.2 Input/Output (I/O) Section
Output devices (motors, lamps)
Electrical isolation
Input devices (switches, sensors)
3.3 Power Supply
Powers PLC modules
Ensures stable operation
Converts AC to DC
3.1 Central Processing Unit (CPU)
Performs logic operations
Manages communication
Executes control program
PLC Operating Principle
4.1 Input Scan
Detects ON/OFF conditions
Updates input image table
Reads status of field inputs
4.2 Program Execution
Solves logic rung by rung
Determines output status
Executes ladder logic
4.3 Output Update
Energizes output devices
Controls process operation
Updates output image table