The invention relates to a system comprising a plurality of medical devices preferably dialysis devices which are connected to a common supply system wherein the system has an evaluating unit which is connected to all devices of the system and is designed in such a way that values set in the different devices and/or specified in the different devices and/or measured values determined in the different devices by means at least one sensor that relate to corresponding quantities are compared with at least one expected value in order to detect faults of the supply system and/or of an individual device.
