A method operates a field bus system, wherein the field bus system has: a gateway, which has a network connection for a network of a specified type and a fieldbus connection for a fieldbus, and a number of fieldbus nodes, wherein the fieldbus nodes are coupled to each other and to the gateway via the fieldbus for the purpose of data exchange. Addressing takes place in the network of the specified type by network addresses, wherein the network addresses have a first part which designates a destination address, and a second part which designates a port of the destination address. The method comprises the steps of: creating a bus configuration, wherein the bus configuration assigns a destination address to a port, and performing a network address translation using the gateway based on the bus configuration created.