Nortel Networks Circuit Card User Manual
Page 441
NT7D16 Data Access card
Page 441 of 906
Circuit Card
Description and Installation
In the case of outbound modem pooling, the DAC answers the data call and
drives the DTR lead ON (modes 0 and 1). Then the calling data module and
the DAC form a transparent link between the calling DTE and the modem.
The DTE user may then enter the appropriate commands to the modem for
dialing a remote modem. When the call is established, the modem may cause
the DAC to disconnect the call by dropping either DSR or DCD.
In the case of inbound modem pooling, the modem must drive the RI lead ON
to activate the DAC. Then the DAC responds by driving the DTR lead ON
and making the unit busy for outbound calls (modes 0 and 1). The modem is
expected to turn DCD to ON within 35 seconds; otherwise, the call will be
dropped by the DAC. If the modem turns DCD ON before the 35-second
timeout, the DAC validates the incoming call and prepares to accept <CR>
from the remote modem for autobaud. See Figure 89 on
for more
details.