Toa SR-D8- M Installation Manual page 21

[connection example 1: redundant configuration of switching hubs]
3
SW-HUB
SW-HUB
2
1 SW-HUB
As shown in the example above, when the CobraNet unit A is operating via the CobraNet PRIMARY and the
CobraNet unit B is operating via the CobraNet SECONDARY, 6 switching hubs are used for communications
between both units. Therefore, in a redundant configuration of switching hubs*, the number of hubs cascade-
connected from the SR-D8-M should be 3 or less.
* A method of connecting a single unit's CobraNet PRIMARY and SECONDARY terminals to each different
switching hub to prevent the system from going down when a cable is broken or power fails.
[connection example 2: Non-redundant configuration of switching hubs]
Star connections
3
SW-HUB
SW-HUB
2
1
SW-HUB
CobraNet unit A
As 7 switching hubs are on the communication path from the CobraNet unit A to the CobraNet unit B, there is
no problem for the system. However, as the number of hubs from the CobraNet unit A to the CobraNet unit C is
8, there may be a system failure.
SR-D8-M
CobraNet PRIMARY
CobraNet PRIMARY
CobraNet unit A
(Operating)
CobraNet unit B
CobraNet
PRIMARY
SR-D8-M
4
SW-HUB
SW-HUB SW-HUB
SW-HUB SW-HUB
SW-HUB
CobraNet SECONDARY
CobraNet
SECONDARY
CobraNet
SECONDARY
(Operating)
CobraNet PRIMARY, SECONDARY
5
SW-HUB
SW-HUB
6
SW-HUB 7
CobraNet unit B
8
SW-HUB
CobraNet unit C
4
SW-HUB
SW-HUB
5
6
SW-HUB
21