Real-time network in the manufacturing plant: Intelligence, not just a link
Joshua Etkin · Robotics and Computer-Integrated Manufacturing · 1989
Local area network (LAN) architecture and protocols have been designed mainly for the office environment. Even with controlled accessing methods the delay is sometimes unacceptable for a large class of real-time applications. Moreover, managing the system-wide control of the manufacturing process is limited by partial knowledge of the system's global state, as viewed by every distributed element. The concept advocated in this paper is adding intelligence to the communication sub-system, thereby reducing the complexity of the application-level computers and enabling them to carry out their mission. The paper supports an adaptive and robust protocol on the lower layers by limiting the waiting time and adding a burst-in mechanism to the contention protocol. A specification and conceptual architecture for a distributed operating system is proposed, in order to minimize the uncertainty gap caused by partial knowledge of the system's global state. The operating system responds quickly to new tasks by establishing a “synthetic” view of the system's global state. The paper presents algorithms that overcome incoherent views, and advocates an architecture that separates system management functions into mechanistic and intelligent categories