Abstract: A control system for office machines, in particular copiers or the like, includes a replacement component which must be exchanged after a specific level of use, the system includes at least one detector of level-of-service and a display unit for the level of use associated with the detector to display the level of use and/or any crossing of an upper limit of level of use. The control system further includes a read/write unit for a coded data carrier, in particular a magnetic or chip card, associated with each replacement component to be integrated. Upon introduction of a coded data carrier, the control system shall reset the level-of-use detector. Such a control system lowers the danger of qualitatively inadequate replacement components being installed.