Explanation About PLC

1. Central Processing Unit (CPU)

CPU functions to control and supervise all pengopersian in the PLC, execute a program stored in memory. Besides CPU also monitors the process and calculate the time when the implementation of the software and translates intermediary program that contains the logic and the time required for data communication with the programmer.

BASIC STRUCTURE PLC

2. Memory

Memory contained in PLC function to save the program and give its location - the location where the results - the results of calculations can be stored therein. PLC uses hardware memory semi-conductors such as RAM (Random Access Memory), ROM (Read Only Memory), and PROM (Programmable Read Only Memory) RAM has a rapid access and program - the program contained therein can be programmed reset in accordance with the wishes of the wearer. RAM is also known as volatile memory, meaning programs that are easily lost if the supply of power outages.

Thus for mengatasiu downed power supply is then given a reserve supply of electric power in the form of a battery stored in RAM. Seringkalo CMOS RAM selected for low power consumption. These batteries have a term of about - about five years before they need replacing.

3. Input / Output

As PLC planned to mngontrol a process or operation of the machine, then the role of the module input / output modules is important because it is an intermediary between the control device to the CPU. A peripheral device connected to the PLC which sends a signal to the PLC is called an input device. Signals entered into the PLC via terminals or via the foot - the foot connecting the unit. The place where the signal enters the so-called PLC input points Input points provides a location in memory which represents the circumstances, the memory location is called input bits. There is also the output bit in the memory which is given by the output points on the unit, the output signal is sent to the output device.

Each input / output has a specific order number and address used for creating programs to monitor one by one input and output activity in the program. Order status indication of input output marked Emiting Light Diode (LED) on a PLC or module input / output, it is intended to facilitate checking the operation of the input / output of the PLC itself.

4. Power Supply

PLC will not operate when there is no mains power supply. Power supply input voltage change into a voltage that is required by the PLC. In other words, convert an electrical power supply PLN power supply (220 V) to power the required CPU or module input / output