NT7D16 Data Access card Page 441 of 906Circuit Card Description and InstallationIn the case of outbound modem pooling, the DAC answers the data call anddrives the DTR lead ON (modes 0 and 1). Then the calling data module andthe DAC form a transparent link between the calling DTE and the modem.The DTE user may then enter the appropriate commands to the modem fordialing a remote modem. When the call is established, the modem may causethe 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 ONto activate the DAC. Then the DAC responds by driving the DTR lead ONand making the unit busy for outbound calls (modes 0 and 1). The modem isexpected to turn DCD to ON within 35 seconds; otherwise, the call will bedropped by the DAC. If the modem turns DCD ON before the 35-secondtimeout, the DAC validates the incoming call and prepares to accept from the remote modem for autobaud. See Figure 89 on page 442 for moredetails.
