Plc Systems


  • Introduction

PLC is short for Programmable Logic Controller. PLC is micro-computer system that processes the data it obtains from sensors in compliance with the program given to it and transmits the results to working units. It was developed in order to overcome the negative sides of control system with relay. In time, its features were improved, and it started to be used for industrial purposes such as sequence control, motion control (linear and revolving (temperature, pressure, moisture, speed), data management (collection data about machine or process, monitoring and reporting)

Structure of PLC

PLC is a micro-computer that contains CPU, input-output interfaces and memory. A repeater, which is also called input interface and output interface, is required for the exchange of signal between input, output equipment and PLC.

The memory capacity of PLC varies according to its type.

The advantages of PLC over Control with Relay

  • Economical
  • Work force saving in design
  • Reduction in production time
  • Small size and standardization
  • The improvement in security
  • Easier to maintain

PLC Output Types

  • PLC with Relay output
  • PLC with triac output
  • PLC with transistor output

There are different ways to main the control contents within PLC memory such as using programming console or personal computer. The program can be either done with circuit symbols or directly through commands.