Transfer of a Modem SessionBecause many modem command variations exist, the sample modem configuration fileslocated at the end of this appendix have been written to capture the largest number ofworkable modem settings.The modem command &Dn (wheren is a number) generally sets the modem responseto the Data Terminal Ready (DTR) signal from the server’s serial port. The desiredresponse is that the modem will hold a connection while DTR is enabled, and drop theconnection when DTR is released. Using this mechanism, the server hangs up on aconnection under normal conditions.Consult your modem manual for its specific response scheme for the &Dn command.Two strategies are available for dealing with the modem’s response to DTR:v Recoveryv PreventionBefore you use one of these strategies, determine if your server’s modem is set upcorrectly to respond to DTR.With the remote terminal connected to serial port 1 and defined as the Primary ConsoleDevice, there are two tests you can perform:1. Will the modem drop the connection after the System initialization completemessage displays at the remote terminal?If Yes, the modem is set up correctly.If No, try another &Dn setting for your server’s modem. See your modem manualfor this information. The &Dn command appears in three places each in three of thesample modem configuration files, as follows:2. Will the server’s modem disconnect when the power drops? You can make thisobservation at the remote terminal by commanding your server to shut down andpower off. (Use the AIX command shutdown -F.) Watch for the message NOCARRIER on your remote terminal.If Yes, this is the correct response. The modem is set up correctly.If No, try another &Dn setting for your server’s modem. See your model manual forthis information. The &Dn command appears in three places each in three of thesample modem configuration files. Only the following sample modem configurationfiles contain the &Dn command (in three places each):v modem_f.cfgv modem_f0.cfgv modem_f1.cfgIf you are using modem_z.cfg or modem_z0.cfg, you cannot control DTR response.If your remote terminal does not disconnect after logging off, you must commandthe remote terminal emulator to hang up. This then breaks the connection.Appendix D. Modem Configurations 331
