Patent ID: 7840713

Claim:
A method for operating a field bus network system having a ring topology, the system including a master unit and a plurality of slave units, which are connected by a field bus in a ring topology, the method comprising: transmitting a data message by the master unit to a slave unit intended for receiving the data message, each of the plurality of slave units having a first counter device and a second counter device, a count of the first counter device being used to display a number of required relay steps via interposed slave units in the ring topology up to the slave unit intended for receiving the data message and a count of the second counter device being used to display a number of completed relay steps via interposed slave units in the ring topology; modifying, by at least one of the slave units, the count of the first counter device using a first predefined algorithm upon receipt of the data message and ascertaining based on the modified count of the first counter device whether it is the slave unit intended to receive the data message; and modifying, by at least one of the slave units, the count of the second counter device using a second predefined algorithm upon receipt of the data message.