Programmable Logic Contoller

PLC known as a series of advance technology on systems modelling, analysis and control, prepared by control system principles. In control system, there are number of generic systems and methods which are encountered in all areas of industry of technology.

PLC is important because all production processes go through a fixed repetitive sequence of operations that involve logical steps and decisions. A PLC is used to control, time and regulate sequence. This controller is important for mechanical application in order to control any mechanical system be more systematically function.

PLC has four main units :-

1. The programme memory - the instructions for the logical control sequence are stored here.

2. The data memory - the status of switches, interlocks, past values of data and other working data is stored here.

3. The output devices - there are hardware/software drivers for the industrial process actuators, such as solenoid switches, motors and valves.

4. The input devices - these are hardware/software drivers for the industrial process sensors such as switch status sensors, proximity detectors, interlock settings and so on.

In order to completing my planning thesis to analysis an elevator system by using a PLC. The purpose use of this PLC controller is to control all the functional system of the elevator. The mechanical system in the lift will controlled by PLC.