Information flow between agricultural machines and tractor is standardised by ISO 11783 (former DIN 9684). ISO-Bus connection between board computers of different agricultural machines and tractor is the solution of the complicated communication problems between electrical and electronic systems. However information transmission between machines and tractor is only a part of the information system inside farm and information system connecting farm with outside production environment (market, banks etc). From the ergonomic point of view whole system should be adapted to the user (operator). In ergonomics such problem is called as compatibility. Compatibility problems were presented in relation to technical equipment of the modern farm.