IBM RS/6000 7025 manual Session

If

your

modem

communicates properly

with

remote users,

it is probably

in control. It

may

be

wise

to

occasionally change

some

of

the

functional

settings and

then

change

them back, just for the sense of

security

that

the

modem

is communicating,

and to

assure

it

has

been initialized recently.

Another strategy, particularly if your system is difficult to access physically, is to protect it with an Uninterruptable Power Source (UPS) and a phone-line surge protector.

In case recovery becomes necessary, your system should be shut down as gracefully as possible. Disconnect the power cable and press the power button to drain capacitance while power is disconnected. Disconnect and reconnect modem

power, then reconnect system power to allow complete reinitialization of your system.

Seamless

Transfer

of a

Modem

Session

There

are

about

as

many modem command variations as there

are

modems. The

sample modem configuration files 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. This

is

the

mechanism

by

which the

server "hangs up" on a connection under normal conditions.

Usually the command &D2 will work, but not always. The sample modem

configuration 2filestake this high percentage position. You should consult

your

modem's

manual

for

its

specific

response

scheme

for

the &Dn

command.

There are two methods for dealing with the modem's response to DTR:

1.Recovery

2.Prevention

Before proceeding with one of these strategies, you need to determine if your server's modem is set up properly to respond to DTR.

D-6IBM RS/6000 7025 F50 Series User's Guide