Nortel Networks 553-3001-211 manual NT7D16 Data Access card Page 429

NT7D16 Data Access card Page 429 of 894

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 86 on page 430 for more details.

Circuit Card Description and Installation