ABSTRACT
Generally speaking, in a distributed computer control system the automation func tions are predominantly stored there where they are needed, i.e. the functions needed at a hierarchical level, are also stored at that level. However, to activate and run the functions at a level at a certain time, relevant initial data are needed on which the function should operate. Such data are as a rule provided by the neigh boring levels, from their databases. In this way the system functions and the rele vant data, distributed across the automation levels, are mutually interconnected [41]. This represent the basic interlevel coordination o f automation activities. In a similar way the data, generated by the functions at one functional level and re quired there, are stored at that level. For instance, data required for direct control and plant supervision are allocated at the field level, i.e. next to the plant instru mentation, whereby the data required for production control are allocated at a higher level, close to the plant manager. The stored data are, however, used for interlevel coordination in the following way: a selected data set o f every level is transferred to its neighboring levels, needed there for initiation and run o f automa tion functions.
