CHAPTER 12 : PROGRAMMABLE LOGIC CONTROL (PLC)

Programmable Logic Control (PLC) is a digitally operating electronic which uses a programming memory for internal storage of instructions for implementing specific functions such as logic, sequencing, timing, counting and arithmetic to control through digital or analog modules, various types of machines or process.

There are some components in PLC :

Power Supply : provides the voltage needed to run the primary PLC components.

I/O Modules : Provide signal conversion and isolation between the internal logic and also level signals inside the PLC and fields high level signal.

Processor : provide intelligence to command and govern the activities of the entire PLC systems.

Programming Device : used to enter the desired program that will determine the sequence of operation and control of process equipment or driven machine.

Memory : used to save the programming in PLC device. There are several memory like flash memory, EPROM, PROM, EEPROM.

There are 2 kind of PLC : fixed/compact PLC and modular PLC.

Advantages of PLC :

• Flexible
• A lot of contact.
• Low Cost
• Safe
• Sort time

Disadvantages of PLC :

• Training for users.
• Required a relay system for safety.

Reference :

Petruzella, D. Frank (1996). Industrial Electronics. New York : McGraw-Hill