Nortel Circuit Card, Installation Manual, Page: 432 / 908

Page 432 of 906 NT7D16 Data Access card
553-3001-211 Standard 3.00 August 2005
Call Set-up abort
The user may abandon the call during the dialogue phase using one of the
following methods:
• Terminal off-line This method is useful for RS-232-C interface only.
The equipment drops Data Terminal Ready (DTR) to indicate an idle
connection. For example, if the equipment is turned off, the DAC
interprets that signal as an idle connection.
• Long break The user sends a break (transmit line held in the OFF or
SPACE state) for more than 1.2 seconds. The break is not transmitted to
the far end. At the end of the long break, the DAC port initiates call
disconnect. The AILU converts the dropping of DTR into a long break
for the RS-422 interface. The long break feature can be disabled through
the Modify menu on the DAC port.
• Three short breaks When the user equipment transmits three breaks to
the far end, the DAC abandons the call. Note that the breaks must be
spaced at least 10 msec apart, and all three must occur within 3 seconds.
Make Port Busy on loss of DTR
This feature is implemented by means of the Make Set Busy (MSB) station
feature. When this is activated, any attempt to reach the specified Data DN
will result in a busy signal.
This application, which operates only in the RS-232-C mode, requires a
non-standard RS-232-C interface. Only two of the possible sixteen RS-232-C
modes can be used: Mode 8 (DCE, Host, Normal DTR, Manual dial), and
Mode 12 (DCE, Terminal, Normal DTR, Manual dial). This feature is
configured in the software, and is downloaded to the DAC.
A DTR timeout period is started whenever the DTR signal lead makes the
transition to OFF. If DTR is returned to ON within the set time period
(5 seconds), the DAC port operates as if this feature was not activated. If the
DTR remains OFF beyond the 5 seconds, the system receives an MSB feature
key message. The DAC sends another MSB message when the DTR returns
to ON, and the port is able to receive inbound calls.