Retrofitting kit to be mounted on an agricultural implement

A retrofitting kit (3) having electrical and/or electronic components to be mounted on an agricultural implement (4), which can be mounted on a tractor (2) and which can be operated in combination therewith, characterized in that the retrofitting kit (3) has implement-specific components for the permanent mounting on the agricultural implement (4), a portable computer unit (6), and a first interface (14) for the electronic connection of the implement-specific components (5) to the portable computer unit (6), which can be used as required, the portable computer unit (6) is designed to be removed from the agricultural implement 4 and to be operated on changing agricultural implements (4), wherein the implement-specific components (5) of the retrofitting kit (3) include sensors (10) for determining process-relevant data and technical transmission means, by means of which the data determined by the sensors (10) can be transmitted to the portable computer unit (6), wherein the portable computer unit (6) includes many building blocks, which are required for the electronic function help of various types of agricultural implements.