Abstract: In this paper, we discuss about Plc i.e. programmable logic Controllers. This paper explores the roles of PLC in automation engineering which is a cross sectional discipline that requires proportional knowledge in hardware and software development and their applications.Earlier in Industry, We used certain control devices which were controlled and wired directly with the system that leads to certain irregularity in the functioning of the whole system. To overcome the in-functionality of the system which was caused by large number of wires, we came cross towards Programmable logic controllers (PLC). The main reason in order to remove irregularity of relays and wiring issue, we prefer PLC to control and monitor the operation of devices in the industry.

Keywords: PLC, automatic control, Ladder Logic, Automation