Industrial local area networks - Concepts, typology, characteristics

Industrial local area networks! "The literature on this subject is prolific. Trade journals regularly address the subject, announcing new products, publishing comparative studies based on a variety of more or less precise criteria, and providing updates on standardization. The ever-increasing number of acronyms does not make the situation any clearer, and many questions arise about the interest of this or that network, its capabilities, its suitability for a given end-user problem. We come across expressions such as corporate LAN, industrial LAN, real-time network, field network, cell network, control room network, factory network, Ethernet network, MMS network, MAP network, TOP, FIP, PROFIBUS, MODBUS, SERCOS, Mini-MAP, MAP-EPA, etc. In fact, what are we talking about here? What's it all about?

That was the introduction to the previous edition of this article. Since then, a few network acronyms have disappeared, but we could add to this a large number of "standards", which often correspond only to highly proprietary products, or even failed attempts at standardization. IEC 61158, EN 50170, EN 50254, IEC 61375, ISO 15745, EN 50325, EN 50295, IEC 62026, ARINC, Safebus, TTP/A and TTP/C, FlexRay, TCN, WTB, MVB are just some of the new acronyms and names to be found in articles [S 7 574], [S 7 575] and [S 7 576] . The question "What's it all about?" is still, if not more, topical. Indeed, as the Internet and the Web have exploded, the economic focus has essentially been on multimedia, telephone, music, video, all these media on digital networks. And today, these technologies are further enriching the choices available in industrial networks. But the need for networks has also continued to grow, and certain industrial solutions have moved into other areas such as embedded systems, home automation with more and more "intelligent" equipment, and telemedicine applications in the home, all of which fall within the scope of industrial local area networks, and which will be studied here.

Our ambition is to clarify the situation of all industrial or embedded local area networks (LANs), by introducing the appropriate concepts and criteria to enable the reader to situate the different networks in relation to each other, but above all in relation to needs. This is why we will first clarify the notion of network and local area network, based on the OSI reference model, whose concepts can be applied to any network, whether public, local, industrial, home automation or embedded, and then the difference between corporate LANs and industrial LANs, even though in both cases certain protocols may be identical.