IT 435 Digital Instrumentation and Controls

1
IT 435 Digital Instrumentation and Controls

• Lecture 7
• Chapter 15

2
Construct a block diagram of a typical PLC

• Programmable Logic Controller
• Microprocessor based computer
• Functions sequentially

3
Major elements of PLC

• CPU
• Memory
• I/O
• Input devices

4
Explain the use of registers and addresses

• Possible to view timer or counter values in a
  register while the device is operating

5
Types of PLCs

• Eptak 200 (Eagle Signal)
• 420 statements
• 32 timers and counters
• 128 internal relays
• Modicon
• Texas Instrument
• Allen Bradley

• Westinghouse
• Square D
• Eaton Corp (Cutler Hammer)
• Reliance Electric
• Omron
• GE Fanuc

6
Typical Prices
7
Sales Features

• Service
• I/O capability
• System compatibility
• Distributed systems

8
Construct a PLC program

• Storage tank flow problem
• Sequence control circuit
• Motor control
• Jogging control
• Plugging control
• Counters
• Counters and Timers

9
Construct a PLC sequencer program

• Dishwasher example