Dezentrales Mikroprozessorsystem mit Farbbildschirmen Zentral Geführt

Growing requirements on process control systems accompanied by increasing system complexity and the advances in applicable new technologies like high performance VLSI’s and fiber optic transmission links lead to distributed multi-microcomputer systems for industrial applications. In this paper it is reported on a computing system being designed in 1975 and supported by the government of the Federal Republic of Germany. The objective of this granted project was to develop a real-time computer system with very advanced features and to test the practicability by an industrial pilot implementation. The system was called RDC-system (Really Distributed Computer Control System) and is described in detail in [10].It is a fault-tolerant real-time computer system with locally distributed microcomputer stations, located in the field near to the technical process. They communicate via a common fiber optic ring bus with a completely decentralized high performance communication protocol. In order to achieve a high reliability use is made of redundancy techniques whether functional and dynamical or in special cases statical masking incorrect outputs.The system is managed by colour TV-displays (EAF-System) being located in the central master control room, input actions are performed by a lightpen, addressing final elements directly via the displayed flowchart of the process. This system is also linked to the optical ring bus, and is fault-tolerant by structural measures, too. Moreover, the whole system is programmed in the high level langwage PEARL, made applicable for multicomputing. The programs are produced in the master control room and down line loaded into the microcomputer stations. By these means the user is able to program the application algorithms by himself.The pilot system was installed at a steel plant of THYSSEN AG. and has been operating since June 1979. Nearly all physical defects were tolerated with graceful degradation of system performance. The system availability attained after some corrections is near to 1 (A_s=1-3,7 η 10-4). The repair actions could take place during normal day-turns.