Architecture and performance of CR4 - a transparent communication mean for field buses and LANs

CarRing 4 (CR4) allows to save cables in wiring harnesses by multiplexing heterogeneous field buses as well as LANs such as Ethernet onto one high-speed, low latency backbone that implements both, hard and isochronous real-time. All existing as well as future field buses and LANs are potentially connectable to CR4, and they do not notice their intermediate backbone. This is called by us `transparent' operation. The maximum source-to-target bandwidth of one CR `ring' is 1.8 Gbps, and its smallest elapsed time for transferring a data frame is 243 ns. The maximum distance of a ring is 40 m, while a whole CR4 system of up to 256 rings can reach 10 km. Applications for CR4 are in real-time communication-systems for buildings and vehicles for land, sea, air and space, as well as for process and factory automation.