Specifications

Operating Modes
2-9
The DAP constantly monitors the dial line for a ringing signal. When ringing is detected,
the DAP automatically answers the call in response to the selected condition. When the
dial backup connection is successfully established, the DAP displays the message
Switched To Dial on the front panel followed by an audible beep. When automatic
answering is disabled or when the selected condition is not present, the DAP informs the
front panel that ringing is detected, but it will not answer the call.
Call Disconnection
Dial line calls can be disconnected automatically or manually. When automatic call
disconnection is enabled, the DAP disconnects the dial line and switches data
transmission back to the dedicated line when the Data Terminal Ready (DTR) signal
from the dial backup port goes Off.
Manual call disconnection requires that you enter commands through the DAP's front
panel or the CMS system console. The DAP then switches transmission back to the
dedicated line.
Switched 56 Integral Dial Operation
The Excalibur DAP's Switched 56 IDBU feature enables both the primary and secondary
channels to transmit data across the dial-up telephone line when the dedicated line fails.
To establish the dial-up connection, the originating DAP must place a telephone call to
the answering DAP. The call can be initiated in three ways: 1) automatically by the
DAP, 2) manually through the DAP's front panel, or 3) manually through the CMS
system console.
The DTE data rate can not be selected when the DAP is in dial backup operation. The
rate selected for normal operation is maintained during dial backup operation with two
exceptions:
• 64 Kbps is automatically changed to 56 Kbps (CC64, LADC, and LDM
operating modes).
• 57.6 Kbps is automatically changed to 52.8 Kbps (C64NI operating mode with
multiport framing disabled). Dial backup operation is not provided for C64NI
operating mode when the data rate is 57.6 Kbps with multiport framing enabled.
When the DAP is in dial backup operation and the DTE data rate is 56 Kbps, no
secondary channel is provided. Therefore, if the unit is a remote, the CMS link that
exists during normal operation is lost when the unit is in dial backup operation. When
the DAP is in dial backup operation and the DTE data rate is 52.8 Kbps or below, a non-
interruptive secondary channel is provided. This channel is compatible with the Milgo
T7 channel. For remote units, the DAP provides an NMI connector for Second Level T7
devices except when the operating mode is DDS.