Practical Industrial Data Networks:Design, Installation and ...

116 Practical Industrial Data Networks: Design, Installation and Troubleshootingappropriate use of a route within the message. The route will include the network addressof the network address of the target device, and any inter-network addresses required. Theroute field of a message may be up to 5 layers deep, is terminated with the value 00, andall unused drops are also set to 00.Figure 8.1Format of Modbus Plus message frameEach network supports up to 64 addressable node devices. Up to 32 nodes can connectdirectly to the network cable over a length of 1500 ft (450 meters). Repeaters can extendthe cable distance to its maximum of 6000 ft (1800 meters) and the node count to itsmaximum of 64. Fiber optic repeaters are available for longer distances.Preferably Terminated atEnd of Cable3m or greaterup to 32 nodes maximummaximum length of 450mNODE1NODE2NODE3Figure 8.2Typical Modbus Plus network with terminationMultiple networks can be inter-networked through bridge plus devices. Messagesoriginating on one network are routed through one or more bridges to a destination onanother network. Bridges do not permit deterministic timing of I/O processes. In