Toa D-2000 Series Installation - Manual (Page 43)

43
D-2000CB
CobraNet unit C
CobraNet unit B
CobraNet unit A
SW-HUB
SW-HUB SW-HUB SW-HUB SW-HUB
SW-HUB SW-HUB SW-HUB SW-HUB
SW-HUB SW-HUB SW-HUB
SW-HUB
1
2
3
4
5
6
7
8
CobraNet PRIMARY, SECONDARY
Star connections
CobraNet PRIMARY CobraNet SECONDARY
CobraNet PRIMARY
(Operating) CobraNet
SECONDARY
CobraNet
PRIMARY CobraNet
SECONDARY
(Operating)
D-2000CB
CobraNet unit B
CobraNet unit A
SW-HUB SW-HUB
SW-HUB SW-HUB
SW-HUB SW-HUB 6
5
4 3
2
1
[Connection example 1: Redundant configuration of switching hubs]
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 D-2000CB 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]
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.