Modem Tricks and HintsThis section should get the fearful started on the (not so) arcane art of
modem tweaking. The commands here are all Hayes AT standard, but all modems are
not equal, so your mileage may vary.Modem SessionsA Modem session allows you to interact with the modem directly. You type
commands, and it will respond. To obtain a modem session, when no connection is
active, go into Setup, then ModemTerminal dialog. This will open a window for interactive
configuration of the modem. Try typing
ATZ (which resets your modem) Your
should get an OK response. Use
FileClose
to end the session.Modem ProfilesOne reason you might want to send the modem commands directly is if you
have a set of modem configurations you want to keep, and not have to specify for
every connection. A good way to do that is via modem profiles. Modems can have
several stored profiles numbered 0,1,... AT&V can be used to
view them all. The default profile is usually 0 (this can be changed via
AT&Y.) The profile currently in use is called the
active profile.When you change a setting, the active profile is modified. The
ATZ command will have the modem load the default profile,
erasing any changes you have made. To save changes, Load the profile you want to
change via ATZn (where
n is the profile number). Make the changes you want,
then save it with AT&Wn. To
have kppp use the profile you want, change the modem initialization string
(SetupModemModem
CommandsInitialization String.) For example
ATZ1 will have the kppp reset the modem and use stored
profile #1.If you want reset you modem to get back to some known starting point, use
AT&F&W to set the active profile to the factory
defaults, and store those settings as the default profile.Examples of profile changes are in the next sectionGetting the modem to hang upSometimes you may find that &kppp; has difficulties hanging up the modem.
This is likely the result of a mismatch between &kppp; settings and those of the
modem. A standard modem uses two methods to decide to hangup: Command, and DTR. The Command method involves
sending an escape sequence to the modem, which puts it in command mode, then
issuing the hangup command (ATH).Outside of &kppp;, when configuring the pppd
package manually, it's often helpful to use the command method, so that one can
exit a terminal session, and then start pppd without
having the modem hangup. In most other situations, the DTR
method is preferred, as it is simpler.DTR (AT&Dn) methodThe DTR method will have the modem hangup whenever
&kppp; stops using the modem. If you obtain a modem session, and query the
state via AT&V, and you can see among the displayed
settings for the active profile a &D0, then the
DTR hangup method is disabled. To enable the
DTR method, use the Terminal button to
get a modem session, then:ATZ# reset to default profileAT&D2# Set to hang up on DTR dropAT&W# Write to default profileHow the DTR method worksWhenever the Data Terminal Ready (DTR) line on the
serial line between the host computer and the modem goes high, the modem hangs
up. When &kppp; opens the serial port, the DTR line is pulled
low, on an external modem, you can see the DTR (or
TR) light come on when this happens. When the
TR light goes out (because &kppp; has closed the serial port,
or something worse!), the modem will hangup.Command methodThe other way to have a modem hang up when connected (used when
AT&Dn where
n is not 2) is to have the
modem accept the command when a session is in progress. To have it hang up
properly, get a modem session, and set the guard time to a short interval like
so:ATZATS12=5AT&WThen use the Guard Time slider in the Modem commands
section to match the register (S12 to this value
5. The modem should then hangup properly.How the Command Method WorksWhen the local modem is connected to a remote modem, it is in the
connect state, where it passes all characters it receives to the
remote modem without interpretation. To have the modem accept the characters
as commands for itself, one must put the modem into the command state. The
escape code does this.The escape code is defined as being three intervals of time whose length
is defined by S12 in fiftieths of a second.Quiet (must last more than S12/50 seconds)Escape character (defined by the register S2, the
default is +), repeated three times (less than
S12/50 seconds between each.Quiet (must last more than S12/50 seconds)Once the modem is in the command state, you can send it commands. To have
it hang up, send the command ATH. The escape codes and the
hangup string used by &kppp; are shown in the Modem Commands dialog.
These should match your modem.Make Tone dialing fasterIf you can use tone dialing, the amount of time it takes to dial can be
changed using the S11 register. It gives the duration (in
100hundreds of a second) to send each tone while dialing. The default is
usually 95 (almost a second.) How fast you can dial depends on the phone
company's switching equipment which handles your line. The minimum duration is
50, almost twice as fast, and that speed often works. ATZ# reset to default profileATS11=50# fastest possible dialing, use a higher number if it doesn't workAT&W# write to default profile