Method for communicating data content within a data network, in particular in an elevator system, the data network comprising a master unit and a plurality of slave units and the master unit and the slave units being connected to one another via data communication paths in order to exchange data telegrams consisting of a large number of bits between one another, each data telegram comprising a header, a datagram region and a checksum, the datagram region being configured for the serial storage of a plurality of datagrams (D 1,..., D n), each datagram (D 1,..., D n) comprising a piece of data content to be communicated and the checksum being calculated uniquely on the basis of the bits in the remainder of the data telegram, the master unit and the slave units being connected to one another in series to form a chain via the data communication paths, the master unit transmitting a data telegram to a first slave unit on an outward data path up to a last slave unit, each of the slave units, with the exception of the last slave unit, forwarding a data telegram received from a direction from the master unit at a first data connection in the direction toward the last slave unit via a second data connection and forwarding a data telegram received from a direction from the last slave unit at the second data connection in the direction toward the master unit via the first data connection, the last slave unit initiating a data return path by returning a datagram (D 1,..., D n) received from the direction from the master unit at a first data connection in a direction toward the master unit via the first data connection, and the data telegram being modified by the slave units exclusively during the data return path, characterized in that the slave units have a processor unit for forwarding and modifying the data telegram and at least one processor unit is configured to read and evaluate the data telegram on the outward data path and, if the data telegram contains a request to the particular slave unit to transmit information to the master unit on the data return path, to begin compiling the requested information immediately after receiving and evaluating the corresponding instruction. the data network comprising a master unit and a plurality of slave units and the master unit and the slave units being connected to one another via data communication paths in order to exchange data telegrams consisting of a large number of bits between one another, each data telegram comprising a header, a datagram region and a checksum, the datagram region being configured for the serial storage of a plurality of datagrams (D 1,..., D n), each datagram (D 1,..., D n) comprising a piece of data content to be communicated and the checksum being calculated uniquely on the basis of the bits in the remainder of the data telegram, the master unit and the slave units being connected to one another in series to form a chain via the data communication paths, the master unit transmitting a data telegram to a first slave unit on an outward data path up to a last slave unit, each of the slave units, with the exception of the last slave unit, forwarding a data telegram received from a direction from the master unit at a first data connection in the direction toward the last slave unit via a second data connection and forwarding a data telegram received from a direction from the last slave unit at the second data connection in the direction toward the master unit via the first data connection, the last slave unit initiating a data return path by returning a datagram (D 1,..., D n) received from the direction from the master unit at a first data connection in a direction toward the master unit via the first data connection, and the data telegram being modified by the slave units exclusively during the data return path, characterized in that the slave units have a processor unit for forwarding and modifying the data telegram and at least one processor unit is configured to read and evaluate the data telegram on the outward data path and, if the data telegram contains a request to the particular slave unit to transmit information to the master unit on the data return path, to begin compiling the requested information immediately after receiving and evaluating the corresponding instruction.