PLC programmable logic controller

The objective of the study is to create a low-cost Programmable Logic Controller (PLC) interfaced with a microcomputer. The PLC consists of the central control unit or the central processing unit, input/output interface, and programming capability which is used to perform such functions as control logic, counting and timing. The PLC is mainly used for the control of industrial sequences and for the monitoring of installations. The establishment of such device allows the performance of several tasks in the field of automation. The PLC is interfaced with the microcomputer through the RS232. The microcomputer is used for programming the PLC through the ladder diagrams and the statement list. These programs process input signals from the attached input devices that would drive output field devices connected to the PLC. The main feature of the PLC is that it is reprogrammable. Such inherent capability allows ease of control of devices instead of the difficult usual rewiring of connections of such devices. The PLC that has been made has its limitations, it is, of course expandable in terms of its hardware design and further enhancement in the software is also recommendable