<HTML ><HEAD ><TITLE >Configure modem to ignore DTR and assert DCD</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK REL="HOME" TITLE="Remote Serial Console HOWTO" HREF="index.html"><LINK REL="UP" TITLE="Upgrading Red Hat Linux from a serial console" HREF="rhl.html"><LINK REL="PREVIOUS" TITLE="Configure the BIOS to use the serial port" HREF="rhl-biosserial.html"><LINK REL="NEXT" TITLE="Prepare a network install floppy diskette" HREF="rhl-preparefloppy.html"></HEAD ><BODY CLASS="SECTION" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >Remote Serial Console HOWTO</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="rhl-biosserial.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Appendix C. Upgrading <SPAN CLASS="PRODUCTNAME" >Red Hat Linux</SPAN > from a serial console</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="rhl-preparefloppy.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECTION" ><H1 CLASS="SECTION" ><A NAME="RHL-IGNOREDTR" ></A >C.3. Configure modem to ignore <SPAN CLASS="ACRONYM" >DTR</SPAN > and assert <SPAN CLASS="ACRONYM" >DCD</SPAN ></H1 ><P >The computer reboots a few times during the upgrade. These reboots hang up the modem. Having to dial in a number of times during the upgrade can become annoying. Altering the modem's configuration to ignore Data Terminal Ready will cause the modem not to hang up when the computer is rebooted. To ignore <SPAN CLASS="ACRONYM" >DTR</SPAN > send the command <B CLASS="COMMAND" >AT&D0</B > to the modem.</P ><P >We may also wish to disconnect during the install to reduce transmission charges. Configuring the modem to hold Data Carrier Detect on will prevent any disconnection and reconnection from being apparent to the installer. Use the command <B CLASS="COMMAND" >AT&C0</B > to always hold <SPAN CLASS="ACRONYM" >DCD</SPAN > high.</P ><P >Apply these changes using the procedure in <A HREF="modem-hayes.html" >Section 12.3</A >, retaining all of the other <TT CLASS="LITERAL" >AT</TT > commands.</P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="rhl-biosserial.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="rhl-preparefloppy.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Configure the <SPAN CLASS="ACRONYM" >BIOS</SPAN > to use the serial port</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="rhl.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Prepare a network install floppy diskette</TD ></TR ></TABLE ></DIV ></BODY ></HTML >