Updating method for coupling a supplementary automation system (AGS) to an overall automation system (AGS) having a basic system and transferring the contents of the main memory area (BAS) of the basic system (BAS) by section-by-section readout and writing to the main memory area (ZAS) of the supplementary system (ZAS), with the same data being written to a buffer memory area both when data is read section-by-section from the main memory area of the basic system and when data is written from and to the main memory area of the basic automation system and being transferred from the buffer memory area to the main memory of the supplementary system.