control system is a major component in an industry which decides the next state of a system. Control system has evolved in a tremendous way with the time. It started with manual control where the human mind plays the logic control processing and it has changed to automatic by representing the logic with hardware electronic relays. Simple logic circuit representing with the relays is advantages where as the complex logic representation is difficult and cost ineffective. The development low cost digital computer has been advantageous in realizing the complex logic. But the general purpose computers are in capable of using at higher temperatures and adverse conditions. So a special purpose computer called PLC (Programmable logic computer) has been implemented in the late 1970 to control the process effectively.