Decentralized automatization structures are a prerequisite for flexible and economic production. Enchainment of these structures with local networks ensures the neccessary information flow. On the plant and cell level the communication on the basis io stable standards has been a firm component of automatization concepts for quite some lime. Ethernet has been established as an acceptable solution and has become part of the MAP specification. The field area, i.e., the lower automatization plane is in discussion at present This area requires a most universal field bus standard for different tasks in the automatization technique. This sector is also penetrated by PRONBUS as a stable base for open communications. For process automation applications the communication system PROFIBUS is supplemented by functional blocks and a devise description language. Producers and users are working together to define the international field bus.