Programmable Logic Controllers

Abstract: Modern software systems are becoming increasingly complex and for that reason extremely difficult to develop and maintain. The size of the development team usually depends on the size and complexity of the software system developed in the project. Good coordination and organization of the team is necessary. One of the main problems of software engineering is that it is a relatively new technical discipline, compared to well-established disciplines such as mechanical and electrical engineering. Plenty of software development projects are still performed in an ad-hoc manner and many of them yield bad and unreliable products or even fail to deliver a working software system. Another issue that makes software engineering techniques difficult to standardize and foment their use in a wider range of software development projects is the extremely rapid development of computer hardware on one hand, and development of programming languages and software development environments on the other hand. Nevertheless, in the last three decades, several software engineering modeling languages and computerized tools have been developed and successfully used. In the late sixties and throughout the seventies, procedural programming languages were dominant and thus the modeling languages were also designe