FidoNet Echomail Archive
comm

<<< Previous Index Next >>>

From: Gord Hannah
To: All
Date: 2010-11-01 01:00:02
Subject: [12 of 12] Comm Primer

   hardware error-control, it is necessary to maintain the DTE rate above
   the DCE rate. This is done so that the modem does not have to wait for
   data to transmit. Serial port locking is typically an optional function
   of one's telecommunications software, and the methods to accomplish it
   are generally detailed in the documentation which accompanies it. As for
   changing the dialing directory entries, this is done for reason outlined
   above to correspond to the DTE rate, the DCE rate will be negotiated by
   the modems upon connection independent of the DTE rate on either end.
   CTS/RTS flow control is necessary to control the flow of data between
   the modem and computer. With data being sent to the modem at a rate
   which is over 2.5 times that at which the modems are exchanging data, a
   method of slowing down the data flow as necessary is required.

Question: When uploading files with my new Generic Xpress, I keep seeing a
message flash up on the screen which says FLOW, what is this, and what
should I do about it?

   Answer: The FLOW message is a normal, non-critical indication that
   CTS/RTS flow control is functioning. It is generated when the data flow
   rate to the modem begins to strain the capacity of its buffer to store
   data which is to be transmitted. With data coming to the modem at a rate
   which is in excess of twice that which it is transmitting, it is a way
   of it saying WHOA MULE! If it is annoying, it can be eliminated by
   allowing the DTE rate to adjust downward to the DCE rate (typically
   referred to as autobaud switching), but it comes at the expense of
   throughput.

Question: I have two computers on the same phone line. Is there anyway I
can transfer files between them with the modems?

    Answer: The answer is yes, you should be able to.  You should be able
    to just simply run a phone extension cord between the two modems, not
    even hooked up to the actual phones in your house.

    When going modem-to-modem, no 'MaBell' hookup is required -- at all:

    1) Get a standard old telephone cable with a modular plug on each,
       (like the one you use to hook a telephone to the wall jack).

    2) Take one end of this phone cable and plug it into the back of one
       of the modems. (Into the jack that you would normally use to hook
       the modem to the wall jack).

    3) Take the other end of this phone cable and plug it into the back
       of the other modem. (Into the jack that you would normally use to
       hook the modem to the wall jack).
              ____________                                 ____________
    Like so: |\           \                               /           /|
             |  \  Back of  \                           /  Back of  /  |
              \   \  External \                       /  External /   /
                \   \__Modem_1__\                   /__Modem_2__/   /
                  \  |          |                   |          |  /
                    \|        | |                   |        | |/
                     ~~~~~~~~~|~~                   ~~~~~~~~~|~~
                              |                              |
                              +------------------------------+
                              Standard Modular Telephone Cable

       Note: You can use the exact same idea with two internal modems or
             a mix of an internal and external.

    4) Now go to the computer hooked up to Modem_1 and load some
       communications program (like Procomm, Telix, Qmodem, etc.) and
       get to the terminal screen.  Type:

         AT

       and press [Enter] to see if the modem is ready.  If it responds
       with:

         OK

       it's ready.

    5) Do the exact same thing (Step "4)") over on the other computer,
       the one hooked up to Modem_2.

    6) On either one of the systems type:

         ATX1D

       This tells this local modem:

         ATtention,
         only give connect responses and ignore the NO DIALTONE,
         and, Dial (originate the call).

    7) On the other other system type:

         ATA

       This tells this local modem:

         ATtention,
         Answer the call.

    That's it.  Now type something -- on either.  They're connected.

This document is a compilation of postings from various venues, with
credits for portions to the following:

           Ted Ball                        Theo Irmer
           Carey Bloodworth                Lawrence Kirby
           David Bowerman                  Bat Lang
           Greg Bretting                   Dave Lyle
           Les Brown                       Ed Mandera
           Patrik Chen                     Bill Mayhew
           Alan Clark                      Paul Munoz-Colman
           Jan Cueleers                    John Navas
           Jeff Derby                      Toby Nixon
           Bill Davidsen                   Stephen Palm
           Floyd Davidson                  Greg Pearson
           Stephen Dunn                    Terry Rutter
           Brett Frankenberger             Stephen Satchel
           Joseph Frankiewicz              Tom Smith
           Vernon Frazee                   Richard Stuart
           Bill Garfield                   Christian Weisgerber
           John Ginnane                    Geoffrey Welsh
           Ed Hall                         Karl Willdig
           Wolfgang Henke                  Mark Young

Comments and/or corrections are welcome either in the echo, Fidonet netmail,
or via Internet e-mail.


Gord Hannah Moderator
Fidonet International COMM Echo
aka: ghannah{at}pris.bc.ca

--- MPost/2 v2.0a
 * Origin: Marsh BBS (c) Dawson Creek BC Canada (1:17/23)
SEEN-BY: 3/0 633/267 640/954 712/0 313 550 620 848
@PATH: 17/23 140/1 261/38 712/848 633/267


<<< Previous Index Next >>>