Local Area Networks (LANs)

As automation in the factory increases, the need for communication between computers, controllers, and other “intelligent” machines has become critical. In the past, when factory automation was limited to the use of programmable controllers (PCs), numerical control (NC) of machines, and similar traditional approaches, communication was not a major limiting factor. Each tool was essentially self-contained, and the communication requirement was primarily a user interface for controlling and updating machine operation. With the accelerated growth of automated tools and processes, however, communication between these entities is required to control not only their operation but their interrelationships as well. To this is added the desire to overlay environmental control, energy management, and materials requirements planning (MRP) to the factory operation. The end result is that intercomputer/controller communication has become the largest single problem to be addressed for factory automation. These interrelationships are shown in Fig. 12.