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diff --git a/doc/kppp/tricks.docbook b/doc/kppp/tricks.docbook new file mode 100644 index 00000000..c2abc3bf --- /dev/null +++ b/doc/kppp/tricks.docbook @@ -0,0 +1,175 @@ +<chapter id="modem-tricks"> +<title>Modem Tricks and Hints</title> + +<para>This 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.</para> + +<sect1 id="modem-sessions"> +<title>Modem Sessions</title> + +<para>A 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 <guibutton>Setup</guibutton>, then <guilabel>Modem</guilabel> +<guibutton>Terminal</guibutton> dialog. This will open a window for interactive +configuration of the modem. Try typing +<userinput><command>ATZ</command></userinput> (which resets your modem) Your +should get an OK response. Use +<menuchoice><guimenu>File</guimenu><guimenuitem>Close</guimenuitem></menuchoice> +to end the session.</para> + +</sect1> + +<sect1 id="modem-profiles"> +<title>Modem Profiles</title> + +<para>One 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,... <command>AT&V</command> can be used to +view them all. The default profile is usually 0 (this can be changed via +<command>AT&Y</command>.) The profile currently in use is called the +<quote>active</quote> profile.</para> + +<para>When you change a setting, the active profile is modified. The +<command>ATZ</command> 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 <command>ATZ<replaceable>n</replaceable></command> (where +<replaceable>n</replaceable> is the profile number). Make the changes you want, +then save it with <command>AT&W<replaceable>n</replaceable></command>. To +have kppp use the profile you want, change the modem initialization string +(<guibutton>Setup</guibutton> <guilabel>Modem</guilabel> <guibutton>Modem +Commands</guibutton> <guilabel>Initialization String</guilabel>.) For example +<command>ATZ1</command> will have the kppp reset the modem and use stored +profile #1.</para> + +<para>If you want reset you modem to get back to some known starting point, use +<command>AT&F&W</command> to set the active profile to the factory +defaults, and store those settings as the default profile.</para> + +<para>Examples of profile changes are in the next section</para> + +</sect1> + +<sect1 id="modem-hangup"> +<title>Getting the modem to hang up</title> + +<para>Sometimes 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: <link +linkend="hangup-command-method">Command</link>, and <link +linkend="hangup-dtr-method"><acronym>DTR</acronym></link>. The Command method involves +sending an escape sequence to the modem, which puts it in command mode, then +issuing the hangup command (<command>ATH</command>).</para> + +<para>Outside of &kppp;, when configuring the <application>pppd</application> +package manually, it's often helpful to use the command method, so that one can +exit a terminal session, and then start <application>pppd</application> without +having the modem hangup. In most other situations, the <acronym>DTR</acronym> +method is preferred, as it is simpler.</para> + +<sect2 id="hangup-dtr-method"> +<title><acronym>DTR</acronym> (<command>AT&Dn</command>) method</title> + +<para>The <acronym>DTR</acronym> method will have the modem hangup whenever +&kppp; stops using the modem. If you obtain a modem session, and query the +state via <command>AT&V</command>, and you can see among the displayed +settings for the active profile a <command>&D0</command>, then the +<acronym>DTR</acronym> hangup method is disabled. To enable the +<acronym>DTR</acronym> method, use the <guibutton>Terminal</guibutton> button to +get a modem session, then:</para> + +<screen> +<userinput><command>ATZ</command></userinput> <lineannotation># reset to default profile</lineannotation> +<userinput><command>AT&D2</command></userinput> <lineannotation># Set to hang up on DTR drop</lineannotation> +<userinput><command>AT&W</command></userinput> <lineannotation># Write to default profile</lineannotation> +</screen> + +<sect3> +<title>How the <acronym>DTR</acronym> method works</title> + +<para>Whenever the Data Terminal Ready (<acronym>DTR</acronym>) 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 <acronym>DTR</acronym> line is pulled +low, on an external modem, you can see the <acronym>DTR</acronym> (or +<acronym>TR</acronym>) light come on when this happens. When the +<acronym>TR</acronym> light goes out (because &kppp; has closed the serial port, +or something worse!), the modem will hangup.</para> +</sect3> + +</sect2> + +<sect2 id="hangup-command-method"> +<title>Command method</title> + +<para>The other way to have a modem hang up when connected (used when +<command>AT&D<replaceable>n</replaceable></command> where +<replaceable>n</replaceable> is not <returnvalue>2</returnvalue>) 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:</para> + +<screen> +<userinput><command>ATZ</command></userinput> +<userinput><command>ATS12=5</command></userinput> +<userinput><command>AT&W</command></userinput> +</screen> + +<para>Then use the <guilabel>Guard Time</guilabel> slider in the Modem commands +section to match the register (<varname>S12</varname> to this value +<returnvalue>5</returnvalue>. The modem should then hangup properly.</para> + +<sect3> +<title>How the Command Method Works</title> + +<para>When the local modem is connected to a remote modem, it is in the +<quote>connect</quote> 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.</para> + +<para>The escape code is defined as being three intervals of time whose length +is defined by <varname>S12</varname> in fiftieths of a second.</para> + +<itemizedlist> +<listitem> +<para>Quiet (must last more than <varname>S12</varname>/50 seconds)</para> +</listitem> +<listitem> +<para>Escape character (defined by the register <varname>S2</varname>, the +default is <quote>+</quote>), repeated three times (less than +<varname>S12</varname>/50 seconds between each.</para> +</listitem> +<listitem> +<para>Quiet (must last more than <varname>S12</varname>/50 seconds)</para> +</listitem> +</itemizedlist> + +<para>Once the modem is in the command state, you can send it commands. To have +it hang up, send the command <command>ATH</command>. The escape codes and the +hangup string used by &kppp; are shown in the <link +linkend="modem-commands"><guilabel>Modem Commands</guilabel></link> dialog. +These should match your modem.</para> + +</sect3> +</sect2> +</sect1> + +<sect1 id="tone-dialing-speedup"> +<title>Make Tone dialing faster</title> + +<para>If you can use tone dialing, the amount of time it takes to dial can be +changed using the <varname>S11</varname> 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. </para> + +<screen> +<userinput><command>ATZ</command></userinput> <lineannotation># reset to default profile</lineannotation> +<userinput><command>ATS11=50</command></userinput> <lineannotation># fastest possible dialing, use a higher number if it doesn't work</lineannotation> +<userinput><command>AT&W</command></userinput> <lineannotation># write to default profile</lineannotation> +</screen> + +</sect1> +</chapter> |