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.