Abstract :
The paper describes some software techniques which have been used at a ceiling board manufacturing site to control the batch weighing and mixing of raw materials in five separate STE-bus Eurocard systems. The well-documented difficulties of creating satisfactory software for any computer system become progressively worse as the complexity of the task increases. Industrial control systems are no exception to this rule and the software has been designed to deal explicitly with six factors of a control system´s complexity: the total number of signals; the number of different types of signal; its degree of configurability; the involvement of human beings in the system´s operation; the number of simultaneous, independent activities; and the number of possible states of each activity