Thursday, March 25, 2010

PLC Hardware Components

PLC consist some main components or hardware which explained as following:

1. Central Processing Unit (CPU)
PLC CPU is PLC component which function of reading and executing program instructions, may allow arithmetic operations, logic operators, block memory moves, computer interfaces, local area network, etc.

2. Memory
Memory is the storage of data in the PLC. Memory is usually inside of CPU module. The data stored in the PLC such, PLC operating system, status of input-output data memory, user-generated programs.

3. Input-Output Module
Input-Output module is the interface of the PLC to the real equipment outside. I/O module in a compact PLC usually is built-in PLC. Then a modular PLC is module I/O separate from the PLC. Generally it divided into two, Digital I/O module and Analog I/O module.

4. System Busses
System busses is the internal paths along which the flow of digital signals within the PLC.

5. Power Supply
Power supply is a source of power for the PLC. It can be an AC voltage and DC voltage. The PLC also has an internal power supply (24VDC) that can be used to provide power to the input/output devices PLC.

6. Programming Devices
Programming devices is a tool to create or edit a PLC program. It was originally a hand held programmer, the benefits of this tool is easy to bring everywhere. But this equipment difficult to use to view the entire program because the program displays are made per line.

PCs and laptops now widely used for programming a much faster and a PC / laptop are also smaller now.

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