svn commit: r44784 - head/en_US.ISO8859-1/books/handbook/serialcomms
Dru Lavigne
dru at FreeBSD.org
Wed May 7 15:22:52 UTC 2014
Author: dru
Date: Wed May 7 15:22:51 2014
New Revision: 44784
URL: http://svnweb.freebsd.org/changeset/doc/44784
Log:
Editorial review of Serial Terminology and Hardware.
Move signal name table into this section.
Add xml ids to the tables in this section.
More commits to come.
Sponsored by: iXsystems
Modified:
head/en_US.ISO8859-1/books/handbook/serialcomms/chapter.xml
Modified: head/en_US.ISO8859-1/books/handbook/serialcomms/chapter.xml
==============================================================================
--- head/en_US.ISO8859-1/books/handbook/serialcomms/chapter.xml Wed May 7 14:02:29 2014 (r44783)
+++ head/en_US.ISO8859-1/books/handbook/serialcomms/chapter.xml Wed May 7 15:22:51 2014 (r44784)
@@ -88,28 +88,28 @@
<para>Data Communications
Equipment<indexterm><primary>DCE</primary></indexterm>
(<acronym>DTE</acronym>) is the other endpoint in a
- serial communication. Typically, it is a modem.</para>
+ serial communication. Typically, it is a modem or serial
+ terminal.</para>
</listitem>
</varlistentry>
<varlistentry>
- <term>RS-232</term>
+ <term><acronym>RS-232</acronym></term>
<listitem>
<para>The original standard which defined hardware serial
communications. It has since been renamed to
- <acronym>TIA</acronym>-232<indexterm><primary>RS-232C
- cables</primary></indexterm>.</para>
+ <acronym>TIA-232</acronym>.</para>
</listitem>
</varlistentry>
</variablelist>
- <para>When talking about communications data rates, this section
- does not use the term <quote>baud</quote>. Baud refers to the
- number of electrical state transitions that may be made in a
+ <para>When referring to communication data rates, this section
+ does not use the term <firstterm>baud</firstterm>. Baud refers to the
+ number of electrical state transitions made in a
period of time, while <acronym>bps</acronym> is the
- <emphasis>correct</emphasis> term to use.</para>
+ correct term to use.</para>
- <para>To connect a modem or serial terminal to a &os; system, a
+ <para>To connect a serial terminal to a &os; system, a
serial port on the computer and the proper cable to connect to
the serial device are needed. Users who are already familiar
with serial hardware and cabling can safely skip this
@@ -120,30 +120,98 @@
<para>There are several different kinds of serial cables. The
two most common types are null-modem cables and standard
- RS-232 cables. The documentation for the hardware should
+ <acronym>RS-232</acronym> cables. The documentation for the hardware should
describe the type of cable required.</para>
+ <para>These two types of cables differ in how the wires are
+ connected to the connector. Each wire represents a signal,
+ with the defined signals summarized in <xref
+ linkend="serialcomms-signal-names"/>. A standard serial
+ cable passes all of the <acronym>RS-232C</acronym> signals
+ straight through. For example, the <quote>Transmitted Data</quote> pin on
+ one end of the cable goes to the <quote>Transmitted
+ Data</quote> pin on the other end. This is the type of
+ cable used to connect a modem to the &os; system, and is also
+ appropriate for some terminals.</para>
+
+ <para>A null-modem cable
+ switches the <quote>Transmitted Data</quote> pin of the
+ connector on one end with the <quote>Received
+ Data</quote> pin on the other end. The connector can be
+ either a <acronym>DB-25</acronym> or a
+ <acronym>DB-9</acronym>.</para>
+
+ <para>A null-modem cable can be constructed
+ using the pin connections summarized in <xref
+ linkend="nullmodem-db25"/>, <xref
+ linkend="nullmodem-db9"/>, and <xref
+ linkend="nullmodem-db9-25"/>. While the standard
+ calls for a straight-through pin 1 to pin 1
+ <quote>Protective Ground</quote> line, it is often
+ omitted. Some terminals work using only pins 2, 3, and 7,
+ while others require different configurations. When in doubt,
+ refer to the documentation for the hardware.</para>
+
<indexterm>
<primary>null-modem cable</primary>
</indexterm>
- <para>A null-modem cable passes some signals, such as
- <quote>Signal Ground</quote>, straight through, but switches
- other signals. For example, the <quote>Transmitted
- Data</quote> pin on one end goes to the <quote>Received
- Data</quote> pin on the other end.</para>
-
- <para>A null-modem cable can be constructed for use with
- terminals. The following table shows the RS-232C <link
- linkend="serialcomms-signal-names">signal names</link> and
- the pin numbers on a DB-25 connector. While the standard
- calls for a straight-through pin 1 to pin 1
- <emphasis>Protective Ground</emphasis> line, it is often
- omitted. Some terminals work using only pins 2, 3, and 7,
- while others require different configurations than the
- examples shown below.</para>
+ <table frame="none" pgwide="1" xml:id="serialcomms-signal-names">
+ <title><acronym>RS-232C</acronym> Signal Names</title>
- <table frame="none" pgwide="1">
+ <tgroup cols="2">
+ <thead>
+ <row>
+ <entry align="left">Acronyms</entry>
+ <entry align="left">Names</entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry><acronym>RD</acronym></entry>
+ <entry>Received Data</entry>
+ </row>
+
+ <row>
+ <entry><acronym>TD</acronym></entry>
+ <entry>Transmitted Data</entry>
+ </row>
+
+ <row>
+ <entry><acronym>DTR</acronym></entry>
+ <entry>Data Terminal Ready</entry>
+ </row>
+
+ <row>
+ <entry><acronym>DSR</acronym></entry>
+ <entry>Data Set Ready</entry>
+ </row>
+
+ <row>
+ <entry><acronym>DCD</acronym></entry>
+ <entry>Data Carrier Detect</entry>
+ </row>
+
+ <row>
+ <entry><acronym>SG</acronym></entry>
+ <entry>Signal Ground</entry>
+ </row>
+
+ <row>
+ <entry><acronym>RTS</acronym></entry>
+ <entry>Request to Send</entry>
+ </row>
+
+ <row>
+ <entry><acronym>CTS</acronym></entry>
+ <entry>Clear to Send</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <table frame="none" pgwide="1" xml:id="nullmodem-db25">
<title>DB-25 to DB-25 Null-Modem Cable</title>
<tgroup cols="5">
@@ -151,7 +219,7 @@
<row>
<entry align="left">Signal</entry>
<entry align="left">Pin #</entry>
- <entry/>
+ <entry></entry>
<entry align="left">Pin #</entry>
<entry align="left">Signal</entry>
</row>
@@ -233,9 +301,7 @@
</tgroup>
</table>
- <para>The next two tables show two other common schemes.</para>
-
- <table frame="none" pgwide="1">
+ <table frame="none" pgwide="1" xml:id="nullmodem-db9">
<title>DB-9 to DB-9 Null-Modem Cable</title>
<tgroup cols="5">
@@ -243,7 +309,7 @@
<row>
<entry align="left">Signal</entry>
<entry align="left">Pin #</entry>
- <entry/>
+ <entry></entry>
<entry align="left">Pin #</entry>
<entry align="left">Signal</entry>
</row>
@@ -325,7 +391,7 @@
</tgroup>
</table>
- <table frame="none" pgwide="1">
+ <table frame="none" pgwide="1" xml:id="nullmodem-db9-25">
<title>DB-9 to DB-25 Null-Modem Cable</title>
<tgroup cols="5">
@@ -333,7 +399,7 @@
<row>
<entry align="left">Signal</entry>
<entry align="left">Pin #</entry>
- <entry/>
+ <entry></entry>
<entry align="left">Pin #</entry>
<entry align="left">Signal</entry>
</row>
@@ -422,34 +488,17 @@
to the other single pin.</para>
</note>
- <para>The above designs seem to be the most popular. In
- another variation, SG connects to SG, TD connects to RD, RTS
- and CTS connect to DCD, DTR connects to DSR, and
- vice-versa.</para>
-
- <indexterm><primary>RS-232C cables</primary></indexterm>
-
- <para>A standard serial cable passes all of the RS-232C signals
- straight through. The <quote>Transmitted Data</quote> pin on
- one end of the cable goes to the <quote>Transmitted
- Data</quote> pin on the other end. This is the type of
- cable used to connect a modem to the &os; system, and is also
- appropriate for some terminals.</para>
-
<para>Serial ports are the devices through which data is
transferred between the &os; host computer and the terminal.
- This section describes the kinds of ports that exist and how
- they are addressed in &os;.</para>
-
- <para>Several kinds of serial ports exist. Before purchasing or
+ Several kinds of serial ports exist. Before purchasing or
constructing a cable, make sure it will fit the ports on the
terminal and on the &os; system.</para>
- <para>Most terminals have DB-25 ports. Personal computers may
- have DB-25 or DB-9 ports. A multiport serial card may have
- RJ-12 or RJ-45 ports.</para>
-
- <para>See the documentation that accompanied the hardware for
+ <para>Most terminals have <acronym>DB-25</acronym> ports. Personal computers may
+ have <acronym>DB-25</acronym> or <acronym>DB-9</acronym>
+ ports. A multiport serial card may have
+ <acronym>RJ-12</acronym> or <acronym>RJ-45/</acronym> ports.
+ See the documentation that accompanied the hardware for
specifications on the kind of port or visually verify the type
of port.</para>
@@ -462,28 +511,29 @@
<para>Call-in ports are named
<filename>/dev/ttyu<replaceable>N</replaceable></filename>
where <replaceable>N</replaceable> is the port number,
- starting from zero. Generally, the call-in port is used
+ starting from zero. If a terminal is connected to the
+ first serial port (<filename>COM1</filename>), use
+ <filename>/dev/ttyu0</filename> to refer to the terminal.
+ If the terminal is on the second serial port
+ (<filename>COM2</filename>), use
+ <filename>/dev/ttyu1</filename>, and so forth. Generally, the call-in port is used
for terminals. Call-in ports require that the serial line
- assert the Data Carrier Detect (<acronym>DCD</acronym>)
+ assert the <quote>Data Carrier Detect</quote>
signal to work correctly.</para>
</listitem>
<listitem>
<para>Call-out ports are named
- <filename>/dev/cuau<replaceable>N</replaceable></filename>.
+ <filename>/dev/cuau<replaceable>N</replaceable></filename>
+ on &os; versions 10.x and higher and
+ <filename>/dev/cuad<replaceable>N</replaceable></filename>
+ on &os; versions 9.x and lower.
Call-out ports are usually not used for terminals, but are
used for modems. The call-out port can be used if the
- serial cable or the terminal does not support the carrier
- detect signal.</para>
+ serial cable or the terminal does not support the <quote>Data Carrier Detect</quote>
+ signal.</para>
</listitem>
</itemizedlist>
-
- <para>If a terminal is connected to the first serial port
- (<filename>COM1</filename>), use
- <filename>/dev/ttyu0</filename> to refer to the terminal. If
- the terminal is on the second serial port
- (<filename>COM2</filename>), use
- <filename>/dev/ttyu1</filename>, and so forth.</para>
</sect2>
<sect2>
@@ -1066,64 +1116,7 @@ ttyu5 "/usr/libexec/getty std.19200"
<indexterm><primary>modem</primary></indexterm>
<para>When using an external modem, a proper cable is needed. A
- standard RS-232C serial cable should suffice as long as all of
- the normal signals are wired:</para>
-
- <table frame="none" pgwide="1" xml:id="serialcomms-signal-names">
- <title>Signal Names</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry align="left">Acronyms</entry>
- <entry align="left">Names</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><acronym>RD</acronym></entry>
- <entry>Received Data</entry>
- </row>
-
- <row>
- <entry><acronym>TD</acronym></entry>
- <entry>Transmitted Data</entry>
- </row>
-
- <row>
- <entry><acronym>DTR</acronym></entry>
- <entry>Data Terminal Ready</entry>
- </row>
-
- <row>
- <entry><acronym>DSR</acronym></entry>
- <entry>Data Set Ready</entry>
- </row>
-
- <row>
- <entry><acronym>DCD</acronym></entry>
- <entry>Data Carrier Detect (RS-232's Received Line
- Signal Detector)</entry>
- </row>
-
- <row>
- <entry><acronym>SG</acronym></entry>
- <entry>Signal Ground</entry>
- </row>
-
- <row>
- <entry><acronym>RTS</acronym></entry>
- <entry>Request to Send</entry>
- </row>
-
- <row>
- <entry><acronym>CTS</acronym></entry>
- <entry>Clear to Send</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
+ standard RS-232C serial cable should suffice.</para>
<para>&os; needs the <acronym>RTS</acronym> and
<acronym>CTS</acronym> signals for flow control at speeds
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