Abstract: A monitoring system for several process control stations includes a redundancy station having a central processing unit and an operating memory to take over the functions of a dropped out process control station. The takeover involves internal bus separation to separate auxiliary and long term storage facilities from immediate processing facilities in each of the process control stations so that upon separation of the latter from the former the redundancy station can effectively take over together with the peripheral equipment and auxiliary devices. The redundancy station cyclically monitors the operating state of the several process control stations and particularly tests status information contained in the particular buffer portion of each of the processing stations. Moreover, relevant data is copied into a standby buffer during each cyclic monitoring step to be used if, pursuant to the next reoccurring supervising and monitoring step, the particular process control station is found to be defective.