The RTFN transport layer of SafetyNET p can be used at process control and manufacturing cell level, where standard Ethernet protocols are in demand and the real-time requirements are lower. RTFN is used to network the RTFL real-time cells and to connect standard Ethernet subscribers, such as visualization devices or service PCs. The RTFN level typically has a tree topology as used in office communication, i. e. with conventional Ethernet. Switches are used to connect the network subscribers in individual point-to-point connections.
RTFN can use two different mechanisms:
The Ethernet MAC frame is used in closed networks. The devices are addressed directly via their MAC address. Then there's the UDP protocol, which is available on most offi ce PCs. In this case the devices are addressed by their IP address. If IP based communication is used, the RTFN frames may also be routed from network to network.
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