Bay Technical Associates BayStack 400-ST1 - Manual (Page 16)

14
Redundant Cascade Stacking Feature
BayStack 400-ST1 Cascade Modules allow you to connect
up to 8 units into a redundant cascade stack. If any single
unit fails or if a cable is accidently disconnected, other
units in the stack remain operational, without interruption.
Figure 6 shows an example of how a stack configuration
reacts to a failed or powered down unit in the stack
configuration:
a. As shown in Figure 6 unit 3 becomes
nonoperational.
This can be the result of a failed unit, or simply
because the unit was powered down.
b. Unit 2 and unit 4, directly upstream and
downstream from unit 3, sense the loss of link
signals from unit 3.
c. Unit 2 and unit 4 automatically loop their
internal stack signals (A and B).
The Cas Up LED for unit 2 and the Cas Dwn
LED for unit 4 turn on (yellow) to indicate the
stack signals are looped.
d. The remaining stack units remain connected.
Although the example shown in Figure 6 shows a failed
unit causing the stack to loop signals at the points of
failure (A and B), the system reacts the same way if a
cable is removed (either deliberately or accidently).