The invention relates to a bus system for transmitting data between data processing units in a network, by means of a bus that consists of two signal lines. The signals at said bus are analog signals which lie within a plurality of non-overlapping frequency bands assigned to the individual data processing units, and these data processing units use a digital communication protocol to communicate with a signal processor unit that comprises a polyphase filter bank, a D/A Converter and a bus-coupling unit being connected downstream of said bank in order to couple the data signal into the bus in a galvanically-isolated manner. The proposed bus system has a simple design with regard to cabling, allows the use of a Standard communication protocol such as Ethernet for the data processing units, and additionally allows data to be transmitted between all network subscribers simultaneously and without restriction.