Specifications

Excalibur Multirate DAP Installation and Operation
2-14
• Always - the DAP always answers calls.
• DDS Line or Local Loop Down - the DAP only answers calls when the DDS
line goes down (due to Out of Service codes, Abnormal Station codes, loss of
multiport framing, or loss of network framing) or when an invalid DDS signal is
received from the network.
• No Signal - the DAP only answers calls when an invalid DDS signal is received
from the network.
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 optional 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 port’s DTE 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.
Asynchronous/ Synchronous Conversion
The Excalibur Multirate DAP can be set to receive data from asynchronous DTEs. The
DAP performs asynchronous to synchronous conversion using the method specified by
CCITT Recommendation V.14.
Note: Tandem operation between two Excalibur DAPs using the V.14 conversion
method can only be established with cascaded synchronous devices. Therefore, V.14
conversion should only be enabled at both ends of a circuit and not at any intermediate
points.
When set for asynchronous operation, the DAP port places each character of data
received from the transmitting DTE into a one-character buffer. It then sends the
characters to the central DAP, using the port's transmit clock for timing. At the receiving
end of the network, the central DAP passes each received character to the port's buffer,
using its receive clock for timing. The port then passes the data through to the DTE.