64 lines
2.6 KiB
Text
64 lines
2.6 KiB
Text
<!-- This is an SGML document in the linuxdoc DTD of the Tutorial for
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Configuring a FreeBSD for Dialup Services by Guy Helmer.
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$Id: serial.sgml,v 1.1 1996-11-28 18:09:30 jfieber Exp $
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The FreeBSD Documentation Project
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<!DOCTYPE linuxdoc PUBLIC "-//FreeBSD//DTD linuxdoc//EN">
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<linuxdoc>
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<article>
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<title> Serial Basics
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<author> FAQ
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<date> 24 Nov 1996, (c) 1996
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<abstract> This section outlines some of the basics to get your serial ports working. This is really just a stepping stone into the section on PPP or Dialout if you are interested in modems.
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</abstract>
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<toc>
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-->
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<sect><heading>Serial Basics<label id="serial"></heading>
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<p><em>Assembled from FAQ.</em>
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This section should give you some general information about serial ports. If you do not find what you want here, check into the Terminal and Dialup sections of the handbook.
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<p>
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The <tt/ttydX/ (or <tt/cuaaX/) device is the regular device
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you will want to open for your applications. When a process opens
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the device, it will have a default set of terminal I/O settings.
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You can see these settings with the command
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<verb>
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stty -a -f /dev/ttyd1
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</verb>
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When you change the settings to this device, the settings are in
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effect until the device is closed. When it is reopened, it goes
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back to the default set. To make changes to the default set, you
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can open and adjust the settings of the ``initial state'' device.
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For example, to turn on <tt/CLOCAL/ mode, 8 bits, and
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<tt>XON/XOFF</tt> flow control by default for ttyd5, do:
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<verb>
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stty -f /dev/ttyid5 clocal cs8 ixon ixoff
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</verb>
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A good place to do this is in <tt>/etc/rc.serial</tt>. Now, an
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application will have these settings by default when it opens
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<tt/ttyd5/. It can still change these settings to its liking,
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though.
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You can also prevent certain settings from being changed by an
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application by making adjustments to the ``lock state'' device.
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For example, to lock the speed of <tt/ttyd5/ to 57600 bps, do
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<verb>
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stty -f /dev/ttyld5 57600
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</verb>
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Now, an application that opens <tt/ttyd5/ and tries to change the
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speed of the port will be stuck with 57600 bps.
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Naturally, you should make the initial state and lock state
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devices writable only by <tt/root/. The <tt/MAKEDEV/ script does
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<bf/NOT/ do this when it creates the device entries.
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