Design considerations for ISOBUS class 3 machinery system's human-machine interaction

International standard ISO 11783 defines a communication bus for agricultural tractor, implement and other devices. ISO 11783-9 provides functionality definitions for agricultural tractor's electronic control units. Class 3 definition of ISO 11783-9 gives the implement possibility to control tractors functions and create advanced automated control functionalities. Safe operation of these machine combinations has arisen as a problem for designers. In this paper design requirements for human-machine interaction are presented and design principles are deducted from those requirements. It is concluded that design and management of safety in machinery combinations based on ISO 11783 network is a system engineering problem and that design principles are more suitable guidelines than strict design requirements.