DATA COMMUNICATION LINK IN A HIERARCHICAL COMMUNICATIONS NETWORK WITH A BUS, OPERATED USING AN INTERROGATION/RESPONSE PROTOCOL, THE SO-CALLED POLLING PROTOCOL

摘要

The invention relates to a data communication link in a hierarchical communication network with a bus, operated according to a polling protocol. Communication elements are arranged in the communications network in several hierarchically classified levels. Optionally, the bus contains hops consisting per se of non-busable point-to-point links. Communication elements are basically fitted with one connecting port each for connection with the upper and lower hierarchical level. The communication elements (KE B1, KE B2) used in the second highest hierarchical level (B) are provided with an interface with the lower level (C) that can be switched in the active direction and an interface with the higher hierarchical level (A). The communications elements (KE C1-3) used in the third highest hierarchical level (C) are provided with an interface with the higher hierarchical level (B) than can be switched in the active direction and an interface with the lower hierarchical level (D). When operating in the second highest hierarchical level, the communication elements are actuated with a permanently adjusted, activated interface in the direction of the lower hierarchical level (C).