270 lines
4.9 KiB
HTML
270 lines
4.9 KiB
HTML
<HTML
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><HEAD
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><TITLE
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>Making serial cables</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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REL="HOME"
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TITLE="Remote Serial Console HOWTO"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Serial cabling"
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HREF="serial.html"><LINK
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REL="PREVIOUS"
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TITLE="Lengths of serial cables"
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HREF="serial-distance.html"><LINK
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REL="NEXT"
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TITLE="Modem configuration"
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HREF="modem.html"></HEAD
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><BODY
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CLASS="SECTION"
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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="serial-distance.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 11. Serial cabling</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="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="SERIAL-MANUFACTURE"
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></A
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>11.5. Making serial cables</H1
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><P
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>If you use a serial console for densely-racked computers you
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will end up making a lot of null-modem serial cables. This section
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has some hints on making serial cables. If you are making more
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than ten cables and live in a city you will probably find it
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economic to have the cables made by a specialty cabling
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firm.</P
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><P
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>Attempt to minimise noise in your cabling design. Many BIOSs
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and boot loaders will wait forever if they receive a single
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character of line noise. You might choose to use shielded UTP
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cables (these require special RJ-45 plugs but use standard RJ-45
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sockets).</P
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><P
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>If the environment has a lot of radio frequency noise then
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use traditional shielded cable and metal RS-232 connector shells.
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Connect the shield in the cable to the computer at
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<EM
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>one</EM
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> end. This can be done by connecting the
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drain wire of the shield it to the Protective Ground (if present)
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or by soldering the drain wire to the shell of the connector. If
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there is a substantial amount of noise also place a ferrite core
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over the shielded cable at both ends of the cable. Follow the
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usual good practices of making the cable to the correct length and
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screwing home the D connectors into the chassis.</P
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><P
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>If you are making one of these cables and have some soldering
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skill, you can easily do the jumpering of the signal wires within
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the backshell of the <SPAN
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CLASS="ACRONYM"
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>DB9</SPAN
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> or
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<SPAN
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CLASS="ACRONYM"
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>DB25</SPAN
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> connector.</P
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><P
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>If you are making a large number of cables then crimping
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systems are much faster than soldering. Again, pin jumpering can
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be done within the backshell.</P
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><P
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>No matter what system is adopted, use the Resistance setting
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of a multimeter to check for dead and shorted pins. A minute here
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can save hours later.</P
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><P
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>For structured cabling systems, space is tight within
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<SPAN
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CLASS="ACRONYM"
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>DB9/RJ-45</SPAN
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> backshells, so the jumpering is better
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done behind the patch panel. The <SPAN
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CLASS="ACRONYM"
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>DB9/RJ-45</SPAN
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>
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connectors present the <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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></SPAN
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> pinout at the DB9 connector and
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present the Yost or Cisco pinout at the <SPAN
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CLASS="ACRONYM"
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>RJ-45</SPAN
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>
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connector.</P
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><DIV
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CLASS="CAUTION"
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><A
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NAME="CAUTION-STRUCTUREDCABLING"
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></A
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><P
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></P
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><TABLE
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CLASS="CAUTION"
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WIDTH="100%"
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BORDER="0"
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><TR
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><TD
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WIDTH="25"
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ALIGN="CENTER"
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VALIGN="TOP"
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><IMG
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SRC="../images/caution.gif"
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HSPACE="5"
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ALT="Caution"></TD
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><TH
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ALIGN="LEFT"
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VALIGN="CENTER"
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><B
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>Incompatible devices in structured cabling systems</B
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></TH
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></TR
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><TR
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><TD
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> </TD
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><TD
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ALIGN="LEFT"
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VALIGN="TOP"
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><P
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>Take care to connect only <SPAN
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CLASS="ACRONYM"
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>RS-232</SPAN
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> devices
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to <SPAN
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CLASS="ACRONYM"
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>RS-232</SPAN
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> devices when patching structured
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cabling systems. Other cables may be carrying ethernet,
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<SPAN
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CLASS="ACRONYM"
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>ISDN</SPAN
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>, telephony, alarm and
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<SPAN
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CLASS="ACRONYM"
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>DC</SPAN
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> power voltages. Connecting incompatible
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voltages may destroy equipment.</P
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></TD
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></TR
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></TABLE
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></DIV
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Footer navigation table"
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WIDTH="100%"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
|
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><A
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HREF="serial-distance.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="34%"
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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="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
|
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WIDTH="33%"
|
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ALIGN="left"
|
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VALIGN="top"
|
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>Lengths of serial cables</TD
|
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><TD
|
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WIDTH="34%"
|
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ALIGN="center"
|
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VALIGN="top"
|
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><A
|
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HREF="serial.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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>Modem configuration</TD
|
|
></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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> |