Link connections

The CAB 4n features built-in Buddy Link functionality for creating backup I/O configurations in mission critical systems.

Each CAB 4n features rear panel, dual BNC connectors labeled LINK IN and LINK OUT. These connectors enable you to connect adjacent CAB units for redundancy.

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 via 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.

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 there is a 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.

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.