Engineering Documentation

Chapter 2 – Network Electrical Systems
Dual Port Ethernet Controller Topology Basics
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Requirements for Fault Tolerant Loop Topology with STP
● Controllers include embedded 3 port switch supporting STP and one IP Address
● Loop of up to 8 controllers installed in a line configuration with maximum cable
distance of 810 m (2655 ft) consisting of 9 × 90 m (295 ft) runs between RJ45
jacks
● Managed Ethernet switches with STP support complete the loop configuration
providing active 10/100BaseTX switch ports at each end of the controller line
● Forwarding is enabled on switch port connected to first controller upstream port 1
● Forwarding is disabled (blocking) on switch port connected to the last controller
downstream port 2 to prevent loop from creating communication storm
● Controller fault such as power loss, malfunction or disconnect from the RJ45 jacks
causes blocking switch port to changes state to forwarding so that downstream
controllers are reconnected
● Controller fault correction causes downstream switch to resume blocking
● Network management using Internet Group Management Protocol (IGMP) allows
alarming as otherwise, a line failure by the customer remains unknown
● Multiple STP loops may be installed in parallel as long as no two loops exceed 17
controllers
● No third-party devices or other switches will be installed in the loop
Fig. 5: Wiring Diagram one Line of up to 8 Dual Port Ethernet Controllers within a STP Loop Configuration
(fault tolerant).
Issues with Non-Fault Tolerant Line Topology
● Controller fault such as power loss, malfunction or disconnect from the RJ45 jacks
causes all downstream controllers to lose connectivity until fault is corrected
● No network management for alarming a line failure so the fault location and status
remains unknown by Customer
Fig. 6: Wiring Diagram one Line of Dual Port Ethernet Controllers (not fault tolerant downstream will lose
connectivity).