A method of operating an agricultural system having a tractor and an implement connected to the tractor, the method comprising - connecting an implement to a tractor; - connecting a tractor control network and an implement control network through a data bus of an agricultural system control network comprising the tractor control network and the implement control network; - transmitting control signals over a signal line of the data bus between the tractor control network and the implement control network; - providing a driving power supply by a tractor power supply to a working unit of the implement connected to the implement control network through a driving power supply line, the tractor power supply being configured to provide a plurality of different driving voltages; - receiving driving power supply control signals in the tractor control network, the driving power supply control signals being sent from the implement control network over the signal line and indicating a present driving voltage which is selected for driving the working unit and is one of the plurality of different driving voltages; - supplying the present driving voltage over the driving power supply line to the working unit; and - operating the working unit by applying the present driving voltage; characterized by - the plurality of different driving voltages being a plurality of different DC driving voltages; - the present driving voltage being a present DC driving voltage; - the receiving of the driving power supply control signals further comprises - receiving driving power supply information signals in the implement control network, the driving power supply information signals indicating the plurality of different DC driving voltages; and - generating the driving power supply control signals by the implement control network in response to the receiving of the driving power supply information signals; and - the driving power supply information signals are updated in the tractor control network during operation of the agricultural system. - connecting an implement to a tractor; - connecting a tractor control network and an implement control network through a data bus of an agricultural system control network comprising the tractor control network and the implement control network; - transmitting control signals over a signal line of the data bus between the tractor control network and the implement control network; - providing a driving power supply by a tractor power supply to a working unit of the implement connected to the implement control network through a driving power supply line, the tractor power supply being configured to provide a plurality of different driving voltages; - receiving driving power supply control signals in the tractor control network, the driving power supply control signals being sent from the implement control network over the signal line and indicating a present driving voltage which is selected for driving the working unit and is one of the plurality of different driving voltages; - supplying the present driving voltage over the driving power supply line to the working unit; and - operating the working unit by applying the present driving voltage; characterized by - the plurality of different driving voltages being a plurality of different DC driving voltages; - the present driving voltage being a present DC driving voltage; - the receiving of the driving power supply control signals further comprises - receiving driving power supply information signals in the implement control network, the driving power supply information signals indicating the plurality of different DC driving voltages; and - generating the driving power supply control signals by the implement control network in response to the receiving of the driving power supply information signals; and - receiving driving power supply information signals in the implement control network, the driving power supply information signals indicating the plurality of different DC driving voltages; and - generating the driving power supply control signals by the implement control network in response to the receiving of the driving power supply information signals; and - the driving power supply information signals are updated in the tractor control network during operation of the agricultural system.