2. Easy
• Acronym of PLC----
• First manufacturer & year
• Types of PLC
– Based on size
– Based on modularity
– Based on application
• Difference b/w PC and a PLC
• Benefits of PLC
• Disadvantages of PLC
3. Medium
• Block diagram and functions
• Types of IO devices
• Symbols
• Scan time and typical values
• Need for optical isolation
• Power supply module
4. Tough
• Relay logic Vs Programmable logic
• Sourcing & sinking
• Power supply modulation at the IO
• Solenoid functioning
• Relay operation
• Proximity sensing