Hardware manual

CAB 4n Hardware Manual
March 15, 2010 Version 1.6.0.0 29
In this configuration, one CAB 4n is declared the primary and transmits data via its LINK
OUT connector. The other CAB 4n is the secondary, or backup, and receives data at its
LINK IN connector. A high quality, broadcast grade video cable, RG-59 with male BNC
connectors on each end, is used to make the connection between the primary and secondary
CABs. A single cable is used for dual CABs in this redundant configuration. The connection
is always LINK OUT (Primary) to LINK IN (Slave). Audio input or output signals appear at
both units, in parallel, so if one fails, the redundant unit will have the same connection.
By nature of the Buddy Link functionality, the secondary unit is always off-line until needed
and therefore the paralleling of the audio connections is of no consequence.
Note: Both units must be configured to use the same audio bundle numbers. For more
information, see Setting the audio bundle numbers.
As long as the primary unit is powered on, and it sees a good CobraNet connection (Ethernet
link status good), and it has not experienced a fault, it generates a signal from its LINK OUT
connector which inhibits the secondary unit from taking over until there is a failure or fault.
The action of the switch-over is different for each type of CAB. In the case of the CAB 4n,
input audio is present simultaneously at both units and both units will pass audio internally.
You can see this by the duplication of audio presence on the front panel meters. However,
relays on the output cards prevent audio passing out of the secondary (slave) CAB.
For input audio, the secondary CAB 4n is prevented from transmitting onto the CobraNet
network by the action of the Buddy Link. The fact that audio is present, but is muted by
relays for output, and by the CobraNet transmission being turned off by the Buddy Link,
means the quick response of the redundant CAB is greatly enhanced.
The Buddy Link feature also monitors the integrity of the link cable. When using dual CABs,
a cable failure will cause the secondary unit to take over transmission onto the CobraNet
network. The Buddy Link functionality can also be placed under software control and is used
in systems where remote access to the link is required.
Note: Using the link connectors for redundancy is limited to dual CAB units. Where
additional CABs are used, additional redundant units must also be added.
As a point of explanation, these are the CAB blocks that are configured in NWare. The
Hardware ID that allows software to control the hardware is set here.