IBM 6H0, Service Manual

Page: 529 / 561

Transfer of a Modem Session
Because many modem command variations exist, the sample modem configuration files
located at the end of this appendix have been written to capture the largest number of
workable modem settings.
The modem command &Dn (where n is a number) generally sets the modem response
to the Data Terminal Ready (DTR) signal from the server’s serial port. The desired
response is that the modem will hold a connection while DTR is enabled, and drop the
connection when DTR is released. Using this mechanism, the server hangs up on a
connection 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
Recovery
v
Prevention
Before you use one of these strategies, determine if your server’s modem is set up
correctly to respond to DTR.
With the remote terminal connected to serial port 1 and defined as the Primary Console
Device, there are two tests you can perform:
1. Will the modem drop the connection after the
System initialization complete
message 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 manual
for this information. The &Dn command appears in three places each in three of the
sample modem configuration files, as follows:
2. Will the server’s modem disconnect when the power drops? You can make this
observation at the remote terminal by commanding your server to shut down and
power off. (Use the AIX command shutdown -F .) Watch for the message
NO
CARRIER
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 for
this information. The &Dn command appears in three places each in three of the
sample modem configuration files. Only the following sample modem configuration
files contain the &Dn command (in three places each):
v
modem_f.cfg
v
modem_f0.cfg
v
modem_f1.cfg
If 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 command
the remote terminal emulator to hang up. This then breaks the connection.
Appendix D. Modem Configurations
509