Specifications

Excalibur Multirate DAP Installation and Operation
2-2
Note: Either the RCP feature or the CMS network management system can use the
secondary channel. Both should not be active simultaneously.
The DAP with interruptive diagnostics has two basic modes of operation:
• Normal - In the Normal mode, data transfer between the DTE and DDS (main
channel data) is allowed to pass unrestricted through the DAP. When the DAP is
configured to operate in Normal mode (local and remote diagnostics parameters
disabled), it is compatible with other DSUs that comply with the requirements
defined in AT&T Publication 62310.
• Diagnostic - In the Diagnostic mode, main channel traffic is blocked by the DAP.
Diagnostic testing of the units and the DDS service can be performed. Access to
tail circuits is not supported in this mode.
Primary Channel Interface
Interruptive diagnostic operation affects the following DTE signals:
• Request-to-Send (RTS) - When this circuit is Off, the unit normally transmits
idle sequences to the network. If interruptive diagnostics are active, the unit may
be transmitting diagnostic data to the network even when RTS is Off.
• Clear-to-Send (CTS) - When interruptive diagnostics are active, CTS is Off.
• Data Carrier Detect (DCD) - An Off condition normally indicates that idle
sequences or a fault condition has been detected by the DAP. When interruptive
diagnostics are active, an Off condition indicates that the network is in
Diagnostic mode. Receive data is Marking during interruptive diagnostics.
Network Management Controller
The Network Management Controller (NMC) can be either a CMS network management
system or the front panel depending on whether the Excalibur Multirate DAP is
configured for external control (CMS) or RCP control. When configured for RCP
control, the front panel assumes the role of controller and performs many of the network
management functions. It monitors, executes, and replies to T7 commands received at
the Network Management Interface (NMI) port.
The NMC can communicate with a central unit without interrupting main channel data.
Communication between the NMC and any remote unit requires switching the DAP into
the Diagnostic mode, which interrupts main channel operation.