ПРОТОКОЛЫ ВЫЧИСЛИТЕЛЬНЫХ СЕТЕЙ ДЛЯ УПРАВЛЕНИЯ ПРОМЫШЛЕННЫМИ ПРОЦЕССАМИ. Protokoly vyčislitel'nyh setej dlâ upravleniâ promyšlennymi processami

Abstract

The technical development made the application of principle of "distributed control" in· process control possible. Appearance of local networks gave new possibilities for creating distributed process control systems. The paper-after having summarized the main features of local networks-introduces the architecture of local networks through the Reference Model of computer networks. Since access methods determine the applicability of local networks for process control, the second part of this paper presents the two fundamental access methods: the CSMA/CD and token concepts. Оп the basis of virtual ring concept the paper reports оn the applicability of the token access method for bus topology networks.