993 lines
17 KiB
HTML
993 lines
17 KiB
HTML
<HTML
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><HEAD
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><TITLE
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>Select a serial speed and parameters</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
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HREF="preparation.html"><LINK
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TITLE="Select a serial port "
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HREF="preparation-setport.html"><LINK
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TITLE="Configure the modem or the null-modem cable"
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HREF="preparation-modem.html"></HEAD
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Remote Serial Console HOWTO</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="preparation-setport.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 2. Preparation</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="preparation-modem.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECTION"
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><H1
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CLASS="SECTION"
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><A
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NAME="PREPARATION-SETSPEED"
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></A
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>2.3. Select a serial speed and parameters</H1
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><P
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>This <I
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CLASS="CITETITLE"
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>HOWTO</I
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> does not discuss the
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<SPAN
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CLASS="ACRONYM"
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>RS-232</SPAN
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> standard, which is formally known as
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<I
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CLASS="CITETITLE"
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><SPAN
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CLASS="ACRONYM"
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>ANSI/TIA/EIA-232-F-1997</SPAN
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> Interface
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Between Data Terminal Equipment and Data Circuit-Terminating
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Equipment Employing Serial Data Interchange</I
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>. For an
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explanation of <SPAN
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CLASS="QUOTE"
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>"bits per second"</SPAN
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>, <SPAN
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CLASS="QUOTE"
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>"start
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bits"</SPAN
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>, <SPAN
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CLASS="QUOTE"
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>"data bits"</SPAN
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>, <SPAN
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CLASS="QUOTE"
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>"parity"</SPAN
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>,
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<SPAN
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CLASS="QUOTE"
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>"stop bits"</SPAN
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> and <SPAN
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CLASS="QUOTE"
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>"flow control"</SPAN
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> refer to the
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<A
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HREF="http://www.tldp.org/HOWTO/Serial-HOWTO.html"
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TARGET="_top"
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><I
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CLASS="CITETITLE"
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>Serial-HOWTO</I
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></A
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>
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and the <A
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HREF="http://www.tldp.org/HOWTO/Modem-HOWTO.html"
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TARGET="_top"
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><I
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CLASS="CITETITLE"
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>Modem-HOWTO</I
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></A
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>.</P
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><P
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>The description of the command syntax for setting the serial
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parameters in the kernel, boot loaders and login applications uses
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the following variables which describe <SPAN
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CLASS="ACRONYM"
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>RS-232</SPAN
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>
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parameters.</P
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><P
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></P
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><DIV
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CLASS="VARIABLELIST"
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><DL
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><DT
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><TT
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CLASS="REPLACEABLE"
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><I
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><speed></I
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></TT
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></DT
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><DD
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><P
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>The speed of the serial link in bits per second.</P
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><P
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>The <SPAN
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CLASS="SYSTEMITEM"
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>Linux</SPAN
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> kernel
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on a modern <SPAN
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CLASS="ACRONYM"
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>PC</SPAN
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> supports a serial console
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speeds of 1200, 2400, 4800, 9600, 19200, 38400, 57600 and 115200
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bits per second.</P
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><P
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>The kernel supports a much wider range of serial bit rates
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when the serial interface is not being used as a serial
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console.<A
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NAME="AEN472"
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HREF="#FTN.AEN472"
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><SPAN
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CLASS="footnote"
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>[1]</SPAN
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></A
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></P
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><P
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>Very recent <SPAN
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CLASS="SYSTEMITEM"
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>Linux</SPAN
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>
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kernels can also offer a serial console using a
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<SPAN
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CLASS="ACRONYM"
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>USB</SPAN
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> serial dongle at speeds of 1200, 2400,
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4800, 9600, 19200, 38400, 57600 and 115200 bits per
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second.</P
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><P
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>Most boot loaders only support a different range of speeds
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than are supported by the kernel.
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<SPAN
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CLASS="PRODUCTNAME"
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>LILO</SPAN
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>
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<SPAN
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CLASS="PRODUCTNUMBER"
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>21.7.5</SPAN
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> supports 110, 150, 300,
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600, 1200, 2400, 4800, 9600, 19200, 38400, 56000, 57600 and
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115200 bits per second. <SPAN
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CLASS="PRODUCTNAME"
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>SYSLINUX</SPAN
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>
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<SPAN
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CLASS="PRODUCTNUMBER"
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>1.67</SPAN
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> supports 75 to 56000 bits
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per second. <SPAN
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CLASS="PRODUCTNAME"
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>GRUB</SPAN
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>
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<SPAN
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CLASS="PRODUCTNUMBER"
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>0.90</SPAN
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> supports 2400, 4800, 9600,
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19200, 38400, 57600 and 115200 bits per second.</P
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><P
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>You must chose the same speed for both the boot loader and
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for the <SPAN
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CLASS="SYSTEMITEM"
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>Linux</SPAN
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> kernel.
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An operating system may use more than one boot loader. For
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example, <SPAN
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CLASS="PRODUCTNAME"
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>Red Hat Linux</SPAN
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> uses
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<SPAN
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CLASS="PRODUCTNAME"
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>SYSLINUX</SPAN
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> to install or upgrade the
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operating system; <SPAN
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CLASS="PRODUCTNAME"
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>LILO</SPAN
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> as the boot
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loader for <SPAN
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CLASS="PRODUCTNAME"
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>Red Hat Linux</SPAN
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>
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<SPAN
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CLASS="PRODUCTNUMBER"
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>7.1</SPAN
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> and earlier; and
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<SPAN
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CLASS="PRODUCTNAME"
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>GRUB</SPAN
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> as the boot loader for
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<SPAN
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CLASS="PRODUCTNAME"
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>Red Hat Linux</SPAN
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>
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<SPAN
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CLASS="PRODUCTNUMBER"
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>7.2</SPAN
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> and later.</P
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><P
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>If you are using a serial terminal or if you are using a
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dumb modem then the bit rate of the terminal or dumb modem must
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also match the bit rate selected in the boot loader and
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kernel.</P
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><P
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>If the serial console is connected to a Hayes-style modem
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slower than 9600<SPAN
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CLASS="ABBREV"
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>bps</SPAN
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> then configure the serial
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console with the same speed as the modem. Modems faster than
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9600<SPAN
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CLASS="ABBREV"
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>bps</SPAN
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> will generally automatically
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synchronize to the speed of the serial port.</P
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><P
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>The selected bit rate must also be supported by the serial
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port's <SPAN
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CLASS="ACRONYM"
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>UART</SPAN
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> semiconductor chip. Early
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<SPAN
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CLASS="ACRONYM"
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>UART</SPAN
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>s without on-chip receive buffers could
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only reliably receive at up to 14400<SPAN
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CLASS="ABBREV"
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>bps</SPAN
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>, this
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includes models 8250A, 82510, 16450 and 16550 (with no
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<I
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CLASS="WORDASWORD"
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>A</I
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>). Recent <SPAN
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CLASS="ACRONYM"
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>UART</SPAN
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>s with
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receive buffers will work at all serial console bit rates, this
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includes models 16550A, 16552, 16650, 16654, 16750, 16850 and
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16950.</P
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><P
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>Unless you have good reason, use the popular bit rate of
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9600 bits per second. This is the default bit rate of a great
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many devices.</P
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><P
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>The speeds that are supported by the kernel, the three
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common boot loaders, and all <SPAN
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CLASS="PRODUCTNAME"
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><SPAN
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CLASS="ACRONYM"
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>IBM</SPAN
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>
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<SPAN
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CLASS="ACRONYM"
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>PC</SPAN
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>s</SPAN
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> capable of running
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<SPAN
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CLASS="SYSTEMITEM"
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>Linux</SPAN
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> are: 2400, 4800,
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9600 and 19200 bits per second. This is a depressingly small
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selection: not slow enough to support a call over an
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international phone circuit and not fast enough to upload large
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files. You may need to choose a speed that will result in a
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less robust software configuration.</P
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><DIV
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CLASS="FIGURE"
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><A
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NAME="PREPARATION-SETSPEED-BPS"
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></A
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><P
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><B
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>Figure 2-2. Syntax for serial bits per second rate, in extended
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Backus-Naur form</B
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></P
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><P
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CLASS="LITERALLAYOUT"
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><TT
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CLASS="REPLACEABLE"
|
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><I
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><speed></I
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></TT
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> ::= <TT
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CLASS="REPLACEABLE"
|
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><I
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><digits></I
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></TT
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><br>
|
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<TT
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CLASS="REPLACEABLE"
|
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><I
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|
><digits></I
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></TT
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> ::= <TT
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|
CLASS="REPLACEABLE"
|
|
><I
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><digit></I
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|
></TT
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|
> | <TT
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|
CLASS="REPLACEABLE"
|
|
><I
|
|
><digit></I
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|
></TT
|
|
><TT
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|
CLASS="REPLACEABLE"
|
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><I
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><digits></I
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></TT
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><br>
|
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<TT
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|
CLASS="REPLACEABLE"
|
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><I
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><digit></I
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></TT
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> ::= <TT
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CLASS="LITERAL"
|
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>0</TT
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> | <TT
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CLASS="LITERAL"
|
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>1</TT
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> | … | <TT
|
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CLASS="LITERAL"
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>9</TT
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></P
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></DIV
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></DD
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><DT
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><TT
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CLASS="REPLACEABLE"
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><I
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><parity></I
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></TT
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></DT
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><DD
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><P
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>Number of parity bits and the interpretation of a parity
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bit if one is present.</P
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><P
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>Allowed values are <TT
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CLASS="LITERAL"
|
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>n</TT
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> for no parity bit,
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<TT
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CLASS="LITERAL"
|
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>e</TT
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> for one bit of even parity and
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<TT
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CLASS="LITERAL"
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>o</TT
|
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> for one bit of odd parity.</P
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><P
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>Using no parity bit and eight data bits is
|
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recommended.</P
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><P
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>If parity is used then even parity is the common
|
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choice.</P
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><P
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>Parity is a simple form of error detection. Modern modems
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have much better error detection and correction. As a result
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the parity bit guards only the data on the cable between the
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modem and the serial port. If this cable has a low error rate,
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and it should, then the parity bit is not required.</P
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><DIV
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CLASS="FIGURE"
|
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><A
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NAME="PREPARATION-SETSPEED-PARITY"
|
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></A
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><P
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><B
|
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>Figure 2-3. Syntax for serial parity, in extended Backus-Naur
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form</B
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></P
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><P
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CLASS="LITERALLAYOUT"
|
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><TT
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CLASS="REPLACEABLE"
|
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><I
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><parity></I
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></TT
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> ::= <TT
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CLASS="LITERAL"
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>n</TT
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> | <TT
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CLASS="LITERAL"
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>e</TT
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> | <TT
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CLASS="LITERAL"
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>o</TT
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></P
|
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></DIV
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></DD
|
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><DT
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><TT
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CLASS="REPLACEABLE"
|
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><I
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><data></I
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></TT
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></DT
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><DD
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><P
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>The number of data bits per character.</P
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><P
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>Allowed values are <TT
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CLASS="LITERAL"
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>7</TT
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> bits or
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<TT
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CLASS="LITERAL"
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>8</TT
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> bits, as Linux uses the
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<SPAN
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CLASS="ACRONYM"
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>ASCII</SPAN
|
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> character set which requires at least
|
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seven bits.</P
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><P
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>Eight data bits are recommended. This allows the link to
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easily be used for file transfers and allows non-English text to
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be presented.</P
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><DIV
|
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CLASS="FIGURE"
|
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><A
|
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NAME="PREPARATION-SETSPEED-DATA"
|
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></A
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><P
|
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><B
|
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>Figure 2-4. Syntax for serial data bits, in extended Backus-Naur
|
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form</B
|
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></P
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><P
|
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CLASS="LITERALLAYOUT"
|
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><TT
|
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CLASS="REPLACEABLE"
|
|
><I
|
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><data></I
|
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></TT
|
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> ::= <TT
|
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CLASS="LITERAL"
|
|
>7</TT
|
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> | <TT
|
|
CLASS="LITERAL"
|
|
>8</TT
|
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></P
|
|
></DIV
|
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></DD
|
|
><DT
|
|
><TT
|
|
CLASS="REPLACEABLE"
|
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><I
|
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><stop></I
|
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></TT
|
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></DT
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><DD
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><P
|
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>The number of stop bit-times.<A
|
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NAME="AEN563"
|
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HREF="#FTN.AEN563"
|
|
><SPAN
|
|
CLASS="footnote"
|
|
>[2]</SPAN
|
|
></A
|
|
></P
|
|
><P
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>Allowed values are <TT
|
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CLASS="LITERAL"
|
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>1</TT
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> or
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<TT
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CLASS="LITERAL"
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>2</TT
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>.</P
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><P
|
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>One stop bit-time is recommended.</P
|
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><P
|
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>If the <SPAN
|
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CLASS="ACRONYM"
|
|
>RS-232</SPAN
|
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> cable is very long then
|
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two stop bit-times may be needed.</P
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|
><P
|
|
>You may occassionally see 1.5 stop bit-times. The intent
|
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is to gain 4% more data throughput when a link is too long for
|
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one stop bit-time but is too short to require two stop
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bit-times. 1.5 stop bit-times is now rare enough to be a hazard
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to use.</P
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|
><DIV
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CLASS="FIGURE"
|
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><A
|
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NAME="PREPARATION-SETSPEED-STOP"
|
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></A
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><P
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><B
|
|
>Figure 2-5. Syntax for serial stop bits, in extended Backus-Naur
|
|
form</B
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></P
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><P
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CLASS="LITERALLAYOUT"
|
|
><TT
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CLASS="REPLACEABLE"
|
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><I
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><stop></I
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></TT
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> ::= <TT
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CLASS="LITERAL"
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>1</TT
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> | <TT
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CLASS="LITERAL"
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>2</TT
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></P
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></DIV
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></DD
|
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><DT
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><TT
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CLASS="REPLACEABLE"
|
|
><I
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><flow_control></I
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></TT
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></DT
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|
><DD
|
|
><P
|
|
>The type of flow control to use.</P
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><P
|
|
>The Linux kernel allows no flow control and
|
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<SPAN
|
|
CLASS="ACRONYM"
|
|
>CTS</SPAN
|
|
>/<SPAN
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CLASS="ACRONYM"
|
|
>RTS</SPAN
|
|
> flow
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|
control.</P
|
|
><P
|
|
>No flow control is the default, this is indicated by
|
|
omitting <flow_control>.</P
|
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><P
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><SPAN
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|
CLASS="ACRONYM"
|
|
>CTS</SPAN
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|
>/<SPAN
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CLASS="ACRONYM"
|
|
>RTS</SPAN
|
|
> flow control
|
|
is recommended, especially if login access is also provided to
|
|
the serial port. This is indicated by a <flow_control> of
|
|
<TT
|
|
CLASS="LITERAL"
|
|
>r</TT
|
|
>.</P
|
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><P
|
|
><SPAN
|
|
CLASS="ACRONYM"
|
|
>CTS</SPAN
|
|
>/<SPAN
|
|
CLASS="ACRONYM"
|
|
>RTS</SPAN
|
|
> flow control
|
|
regulates the flow of chatacters. The computer does not send
|
|
characters until Clear To Send is asserted by the modem. If the
|
|
computer is has enough buffering to recieve characters from the
|
|
modem the computer asserts Ready to Send. Thus neither the
|
|
computer nor the modem's buffers are filled to
|
|
overflowing.</P
|
|
><DIV
|
|
CLASS="CAUTION"
|
|
><P
|
|
></P
|
|
><TABLE
|
|
CLASS="CAUTION"
|
|
WIDTH="90%"
|
|
BORDER="0"
|
|
><TR
|
|
><TD
|
|
WIDTH="25"
|
|
ALIGN="CENTER"
|
|
VALIGN="TOP"
|
|
><IMG
|
|
SRC="../images/caution.gif"
|
|
HSPACE="5"
|
|
ALT="Caution"></TD
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="TOP"
|
|
><P
|
|
>The kernel's
|
|
<SPAN
|
|
CLASS="ACRONYM"
|
|
>CTS</SPAN
|
|
>/<SPAN
|
|
CLASS="ACRONYM"
|
|
>RTS</SPAN
|
|
> flow control is
|
|
currently buggy. Machines can take a significant time to write
|
|
console messages if flow control is enabled but
|
|
<SPAN
|
|
CLASS="ACRONYM"
|
|
>CTS</SPAN
|
|
> will never be asserted (as occurs when
|
|
there is no call present on a modem or no session on a null
|
|
modem cable or cable to a terminal server). As a result of the
|
|
large number of kernel messages when the kernel is started a
|
|
machine configured with the kernel's
|
|
<SPAN
|
|
CLASS="ACRONYM"
|
|
>CTS</SPAN
|
|
>/<SPAN
|
|
CLASS="ACRONYM"
|
|
>RTS</SPAN
|
|
> flow control can
|
|
take many minutes to reboot.</P
|
|
><P
|
|
>The kernel's
|
|
<SPAN
|
|
CLASS="ACRONYM"
|
|
>CTS</SPAN
|
|
>/<SPAN
|
|
CLASS="ACRONYM"
|
|
>RTS</SPAN
|
|
> flow control
|
|
cannot be recommended at this time. The
|
|
<I
|
|
CLASS="CITETITLE"
|
|
>HOWTO</I
|
|
>'s author has a kernel patch
|
|
available which he is seeking to have included in the
|
|
mainstream kernel source code.</P
|
|
><P
|
|
>The <SPAN
|
|
CLASS="ACRONYM"
|
|
>CTS</SPAN
|
|
>/<SPAN
|
|
CLASS="ACRONYM"
|
|
>RTS</SPAN
|
|
> flow
|
|
control in user-space applications does not share the kernel's
|
|
bugs and <SPAN
|
|
CLASS="ACRONYM"
|
|
>CTS</SPAN
|
|
>/<SPAN
|
|
CLASS="ACRONYM"
|
|
>RTS</SPAN
|
|
> flow
|
|
control is still recommended for
|
|
<SPAN
|
|
CLASS="APPLICATION"
|
|
>getty</SPAN
|
|
>.</P
|
|
></TD
|
|
></TR
|
|
></TABLE
|
|
></DIV
|
|
><DIV
|
|
CLASS="FIGURE"
|
|
><A
|
|
NAME="PREPARATION-SETSPEED-FLOW"
|
|
></A
|
|
><P
|
|
><B
|
|
>Figure 2-6. Syntax for serial flow control, in extended Backus-Naur
|
|
form</B
|
|
></P
|
|
><P
|
|
CLASS="LITERALLAYOUT"
|
|
><TT
|
|
CLASS="REPLACEABLE"
|
|
><I
|
|
><flow_control></I
|
|
></TT
|
|
> ::= <TT
|
|
CLASS="REPLACEABLE"
|
|
><I
|
|
><nil></I
|
|
></TT
|
|
> | <TT
|
|
CLASS="LITERAL"
|
|
>r</TT
|
|
></P
|
|
></DIV
|
|
></DD
|
|
></DL
|
|
></DIV
|
|
><P
|
|
>At present the <SPAN
|
|
CLASS="ACRONYM"
|
|
>RS-232</SPAN
|
|
> status lines are
|
|
ignored by the kernel. A kernel message will be printed even if
|
|
Data Carrier Detect and Data Set Ready are not asserted. This
|
|
leads to the kernel messages being sent to a modem which is idle
|
|
and in command mode.</P
|
|
><P
|
|
>The console's slack interpretation of <SPAN
|
|
CLASS="ACRONYM"
|
|
>CTS</SPAN
|
|
>,
|
|
<SPAN
|
|
CLASS="ACRONYM"
|
|
>DSR</SPAN
|
|
> and <SPAN
|
|
CLASS="ACRONYM"
|
|
>DCD</SPAN
|
|
> makes it
|
|
impossible to connect a serial console to an
|
|
<SPAN
|
|
CLASS="ACRONYM"
|
|
>RS-232</SPAN
|
|
> multi-drop circuit. Multi-drop circuits
|
|
have more than two computers on the circuit; they are traditionally
|
|
four-wire, satelite or wireless services.</P
|
|
><P
|
|
>The Linux kernel uses the syntax in <A
|
|
HREF="preparation-setspeed.html#PREPARATION-SETSPEED-MODESYNTAX"
|
|
>Figure 2-7</A
|
|
> to describe the serial
|
|
parameters. Many boot loaders use a variation of the syntax used
|
|
by the Linux kernel.</P
|
|
><DIV
|
|
CLASS="FIGURE"
|
|
><A
|
|
NAME="PREPARATION-SETSPEED-MODESYNTAX"
|
|
></A
|
|
><P
|
|
><B
|
|
>Figure 2-7. Syntax for kernel serial parameters, in extended
|
|
Backus-Naur form</B
|
|
></P
|
|
><P
|
|
CLASS="LITERALLAYOUT"
|
|
><TT
|
|
CLASS="REPLACEABLE"
|
|
><I
|
|
><mode></I
|
|
></TT
|
|
> ::= <TT
|
|
CLASS="REPLACEABLE"
|
|
><I
|
|
><speed></I
|
|
></TT
|
|
><TT
|
|
CLASS="REPLACEABLE"
|
|
><I
|
|
><parity></I
|
|
></TT
|
|
><TT
|
|
CLASS="REPLACEABLE"
|
|
><I
|
|
><data></I
|
|
></TT
|
|
><TT
|
|
CLASS="REPLACEABLE"
|
|
><I
|
|
><flow_control></I
|
|
></TT
|
|
></P
|
|
></DIV
|
|
><P
|
|
>Note that <TT
|
|
CLASS="REPLACEABLE"
|
|
><I
|
|
><mode></I
|
|
></TT
|
|
> does not
|
|
include <TT
|
|
CLASS="REPLACEABLE"
|
|
><I
|
|
><stop></I
|
|
></TT
|
|
>. The kernel
|
|
assumes the number of stop bits to be one. This shortcoming needs
|
|
to be considered when deploying long <SPAN
|
|
CLASS="ACRONYM"
|
|
>RS-232</SPAN
|
|
>
|
|
cables.</P
|
|
><P
|
|
>Most boot loaders default to <TT
|
|
CLASS="LITERAL"
|
|
>9600n8</TT
|
|
>. A
|
|
common default found on older terminals is
|
|
<TT
|
|
CLASS="LITERAL"
|
|
>9600e7</TT
|
|
>.</P
|
|
><P
|
|
>Use <TT
|
|
CLASS="LITERAL"
|
|
>9600n8</TT
|
|
> if possible, as this is the
|
|
default for most Linux software and modern devices.</P
|
|
><P
|
|
>This <I
|
|
CLASS="CITETITLE"
|
|
>HOWTO</I
|
|
> always configures the
|
|
serial speed and parameters, even where not strictly necessary.
|
|
This is so that people configuring parameters other than the
|
|
recommended and common default value <TT
|
|
CLASS="LITERAL"
|
|
>9600n8</TT
|
|
>
|
|
will know what to alter.</P
|
|
></DIV
|
|
><H3
|
|
CLASS="FOOTNOTES"
|
|
>Notes</H3
|
|
><TABLE
|
|
BORDER="0"
|
|
CLASS="FOOTNOTES"
|
|
WIDTH="100%"
|
|
><TR
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="TOP"
|
|
WIDTH="5%"
|
|
><A
|
|
NAME="FTN.AEN472"
|
|
HREF="preparation-setspeed.html#AEN472"
|
|
><SPAN
|
|
CLASS="footnote"
|
|
>[1]</SPAN
|
|
></A
|
|
></TD
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="TOP"
|
|
WIDTH="95%"
|
|
><P
|
|
>There is no good reason for this
|
|
difference. Feel free to submit a patch to the linux-kernel
|
|
mailing list to correct this oddity.</P
|
|
></TD
|
|
></TR
|
|
><TR
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="TOP"
|
|
WIDTH="5%"
|
|
><A
|
|
NAME="FTN.AEN563"
|
|
HREF="preparation-setspeed.html#AEN563"
|
|
><SPAN
|
|
CLASS="footnote"
|
|
>[2]</SPAN
|
|
></A
|
|
></TD
|
|
><TD
|
|
ALIGN="LEFT"
|
|
VALIGN="TOP"
|
|
WIDTH="95%"
|
|
><P
|
|
>A <I
|
|
CLASS="WORDASWORD"
|
|
>bit-time</I
|
|
> is the time taken to
|
|
transmit one bit. The distinction between
|
|
<I
|
|
CLASS="WORDASWORD"
|
|
>bit-times</I
|
|
> of signal and
|
|
<I
|
|
CLASS="WORDASWORD"
|
|
>bits</I
|
|
> of data is apparent when you
|
|
consider that 1.5 bit-times of signal is possible but that 1.5
|
|
bits of data is impossible.</P
|
|
></TD
|
|
></TR
|
|
></TABLE
|
|
><DIV
|
|
CLASS="NAVFOOTER"
|
|
><HR
|
|
ALIGN="LEFT"
|
|
WIDTH="100%"><TABLE
|
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SUMMARY="Footer navigation table"
|
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WIDTH="100%"
|
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BORDER="0"
|
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CELLPADDING="0"
|
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CELLSPACING="0"
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|
><TR
|
|
><TD
|
|
WIDTH="33%"
|
|
ALIGN="left"
|
|
VALIGN="top"
|
|
><A
|
|
HREF="preparation-setport.html"
|
|
ACCESSKEY="P"
|
|
>Prev</A
|
|
></TD
|
|
><TD
|
|
WIDTH="34%"
|
|
ALIGN="center"
|
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VALIGN="top"
|
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><A
|
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HREF="index.html"
|
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ACCESSKEY="H"
|
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>Home</A
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></TD
|
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><TD
|
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WIDTH="33%"
|
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ALIGN="right"
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VALIGN="top"
|
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><A
|
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HREF="preparation-modem.html"
|
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ACCESSKEY="N"
|
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>Next</A
|
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></TD
|
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></TR
|
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><TR
|
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><TD
|
|
WIDTH="33%"
|
|
ALIGN="left"
|
|
VALIGN="top"
|
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>Select a serial port</TD
|
|
><TD
|
|
WIDTH="34%"
|
|
ALIGN="center"
|
|
VALIGN="top"
|
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><A
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HREF="preparation.html"
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ACCESSKEY="U"
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>Up</A
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></TD
|
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><TD
|
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WIDTH="33%"
|
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ALIGN="right"
|
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VALIGN="top"
|
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>Configure the modem or the null-modem cable</TD
|
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></TR
|
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></TABLE
|
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></DIV
|
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></BODY
|
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></HTML
|
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