3. PLC Hardware Specifications A p

3. PLC Hardware Specifications A programmable logic controller is a digital computer used for automation of electromechanical processes. Industrial PLC describes the computing unit of any industrial automation system and therefore need to meet several challenging requirements such as high reliability, environmental noise and influence immunity and also enhanced protection classes (e.g. water-resistant and dust sealed). PLCs also satisfy the needs of continuous 24 hours/7 days operation and availability over a wide environmental temperature range as well as real-time operation capability and security and safety enhancements. The input/output arrangements may be built into a simple PLC, or the PLC may have external I/O modules attached to a computer network that plugs into the PLC. The communications interface is used to receive and transmit data on communication networks from or to other remote PLCs. It is concerned with such actions as device verification, data acquisition, synchronization between user applications and connection management. Some of the advantages of using PLC include: • Programming the PLC is easier than wiring the relay control panel. • The PLC can be reprogrammed. ConventionalControls must be rewired and are often scrapped instead. • PLC takes less floor space then relay control panels. • Maintenance of the PLC is easier, and reliability is greater. • PLC can be connected to the plant computer systems more easily than relays. We have chosen PLC_200 SeriesProgrammable Logic Controllers with the following features.