Operation Of Self-Healing Ring - TC Communications TC2400 User Manual

Operation of Self-Healing Ring

In a poll-response environment, the host controller broadcasts poll messages to every RTU. Because the
poll message is embedded with a specific RTU's ID (or address), only the RTU with the correct ID responds
to the Master's polling. The TC2400's function is to convert the electrical signal from the Host controller
to a fiber optic signal and transmit that signal in both ring directions, as shown in Figure 2.
The first Slave unit in the ring intercepts the Master's broadcast message and forwards it to the downstream
Slave unit. Each subsequent Slave forwards the broadcast message until it reaches the last Slave in the ring.
The RTU with the correct ID then sends a response message. Each Slave then forwards the response
message through the ring until it eventually reaches the Master unit.
Figure 2. Ring Broadcast Directions
Figure 3. Ring Operation Under Normal Conditions
- 4 -
TC2400 & TC2401
Ring User's Manual
Rev. 1.7