A field bus system includes at least one bus module designed as a master module with at least one connecting device for connection to a network and with at least one port for connecting a parameterizable IO link device. The field bus system uses a data storage device which is designed as an IO link device and which can be connected to the at least one port for connecting an IO link device and in which all parameters of the IO link devices connected to the master module are stored and can be read by the master module.