Method, system, and bus coupler for exchanging data between a higher-level network and a lower-level network

A method for exchanging data between a network (209), on which Ethernet telegrams may be transmitted, and multiple bus users (40-70) via a bus coupler (30), the network being connected to an external interface of the bus coupler (30), and the multiple bus users (40-70) being connected in series to a ring-shaped transmission path via an internal interface (34, 35) of the bus coupler (30), the method comprising:

• converting, in a converter device (33), an Ethernet telegram (170) received via the external interface of the bus coupler (30) to an internal data telegram (180) that contains no control data of the Ethernet telegram and that contains at least one state information field (201) for internal control data;
• relaying the internal data telegram (180) to the internal interface of the bus coupler (30);
• outputting, from the internal interface of the bus coupler, the internal data telegram (180) on the ring-shaped transmitted path;
• and
• when the internal data telegram passes through the corresponding bus user on the ring-shaped transmission path, exchanging, by each bus user connected to the internal interface, the payload data intended for the bus user with the internal data telegram circulating on the transmission path;
• wherein the bus user is able to extract payload data from a data block, associated with the bus user, in the data field (211) of the internal data telegram (180), and to extract internal control data from the at least one state information field (201) of the internal data telegram (180), and to insert payload data into the data block, associated with the bus user, of the data field (211) of the internal data telegram, and to insert internal control data into the at least one state information field (201) of the internal data telegram.