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Demon Internet Ltd

Gateway House 322 Regents Park Road Finchley, London, N3 2QQ 0181-371 1234 (Sales - London) 0131-552 0344 (Sales - Edinburgh) 0181-371 1010 (HelpLine) 0181-371 1150 (Fax) 0181-371 1000 (Switchboard) email internet@demon.net

MODEM.TXT - INFORMATION ON CONFIGURING A MODEM FOR CONNECTING TO THE INTERNET Last updated: 19 April 1995

The latest version of this document is available from ftp.demon.co.uk:/pub/doc/Modem.txt

Contents

1. General 2. Essentials 3. Telephone Exchange 4. Internal Modems 5. Which Phone Number 6. Modem and Telephone Leads 7. Serial Chips 8. Speed 9. Trouble Shooting 10. Software and Other Factors 11. Help for Specific Computers 11.0. IBM PC Compatibles running DOS 11.1. OS/2 12. Individual Modem Settings 12.0. Setting up a kind of modem not described below 12.1. Setting Up a US Robotics/Miracom Modem 12.2. Apple Express Modem 12.3. BT NS 2232 M 12.4. Dowty 12.5. Dynalink 12.6. Gateway 12.7. Global Village 12.8. Mistral 12.9. Multitech 12.10. Pace Microlin 12.11. Pace Mobifax 12.12. Racal 12.13. Rockwell chipset modems 12.14. SmartOne 12.15. Supra modems 12.16. Yoriko modems 12.17. Zoltrix 12.18. Zoom modems 12.19. Zyxel 13. Testing 14. Finally

1. General

This document will point out some general essentials and advice on setting up your modem. A section at the end discusses specifics regarding a DOS setup running the KA9Q NET.EXE program. Due to the vast combinations of computer and modem setups it is impossible to give specific help for all types.

Making an Internet (IP - Internet Protocol) connection via a modem is very different from a standard dial-up connection. Do not assume that just because you can download from a BBS (and maybe upload) or use other services that you have your communication (comms) set-up 100% sorted out. Due to the nature of IP, if you get errors, throughput can be hit very badly. Under IP information is sent in packets and for maximum speed these should generally be as large as possible up to a maximum of about 1500 characters. If a packet gets messed up (garbled) its entire contents will have to be resent - hence a large speed degradation may occur.

One exception to this is when an interactive sessions are sharing a TCP/IP link with more voluminous transfers such as NNTP or SMTP. In this case it can be preferable to have smaller transmission units (Maximum Transmission Units setting or MTU) so that keystrokes/screen updates will fit into the data stream with less delay. If a large MTU is used this can lead to what feels like a jerky or intermittent session.

Enough of the technical parts, there follows some sound advice that everybody should take note of.

2. Essentials

        Correct modem settings:
             Full hardware handshaking (CTS/RTS),
             Flow control
             XON/XOFF (software handshaking) set to off
             Settings must be bi-directional where appropriate.
       A full specification modem cable (open yours up - if it has
       only 3 wires it is no good).
       A serial chip that can cope with the high speeds (if using a
       high speed modem).  Extended memory drivers and Terminate Stay
       Residents (TSRs) etc. can interfere with the handling of
       interrupts from serial chips.

3. Telephone Exchange

        The Demon Internet Service (DIS) is on modern digital exchanges
        so you should have little trouble with ringing tones etc when
        connecting to us.  If you are on an older exchange, your modem
        may not recognise the dialling tone.  If this happens, look in
        your manual and change the setting that overrides the dial tone
        recognition.
        Note that when you make changes to a modem's settings you
        should always reset the modem first, make the change and then
        save the settings.  You will need a comms or "terminal
        emulation" package such as Telix, Procomm, Window's Terminal, Z-
        Term, Microphone etc.  Look in your modem manual for
        instructions.  Mostly you will be able to type ATZ <return> to
        reset your modem.  On a US Robotics/Miracom modem you could
        type:
        ATZ            Reset the modem
        ATX3           Alter a setting
        AT&W           Write the settings to Non-Volatile RAM (NVRAM)
        The last bit (AT&W) is useful as it means that when the modem
        is reset, it will remember the settings you have stored.
        If going through a private telephone network (or PABX) first,
        you will probably need to dial a number such as 9 to get an
        outside line.  Make sure your dial string has this in.  You may
        need to separate this from the number to dial by a separator
        such as a comma so that there is a pause to give your telephone
        system time to give you an outside line:
        9,01813434848

4. Internal Modems

        Internal modems have the advantage of not having a serial lead
        to worry about but the disadvantage of using an extra interrupt
        and generally don't have any lights to let you know what is
        going on.  Ensure that the interrupt on which the modem sits
        does not interfere with any others - refer to the setup program
        for your computer and your modem manual.  This may require
        altering a jumper (a small connector) on the main computer
        board (mother board) on your computer or on a separate board.
        This should be well documented and is well within the scope of
        the average user.  Ensure that the modem is seated correctly in
        the expansion slot.

5. Which Phone Number

        We have multiple Points of Presence (PoPs) - please see
        /pub/doc/Demon.txt for details.  Thus you will have a choice of
        numbers to ring.  You may use any of our PoPs at any time.

6. Modem and Telephone Leads

        Your modem lead should be in good condition and preferably not
        wrapped in a tight circle or running parallel to high power
        cables etc.  This will normally only affect longer runs and, as
        your cable should be earthed, will not often be a problem.  The
        cable should be connected securely at both ends as should the
        telephone cable.  If you suspect your telephone socket may be
        causing a problem then test it with a standard plug in
        telephone.  Use the correct type of modem lead - they vary from
        country to country.

7. Serial Chips

        The type of serial chip (Universal Asynchronous
        Receiver/Transmitter - UART) in use can make a big difference
        to comms performance/reliability.  At higher speed the computer
        can sometimes not service the serial chip fast enough to catch
        all of the characters arriving down the line.  This problem
        increases if running under a multi-tasker such as Windows,
        certain memory managers and other TSRs.

8. Speed

        Close to every modem user's heart is the speed at which they
        can operate.  There are two different speeds: the first is the
        speed at which a modem can talk to another modem; the second is
        the speed at which the modem can talk to its controlling
        computer (the DTE rate).
        Firstly, we will discuss the connect rate.  A V.22bis modem can
        connect at a speed of 2,400 bits per second.  There are 8 bits
        in a byte (a byte is usually one character) so that is a
        maximum of 300 characters per second (cps).  Due to start and
        stop bits, each byte will take 10 bits reducing the speed to
        240 characters per second.  When running over IP there is a
        slight overhead and so you will never see this maximum.
        However, as you can (and will) have several things happening at
        once, you will be able to make very good use of your available
        bandwidth.
        Many modems have compression protocols built in to them.  MNP/4
        and V42 use synchronous connections to provide an error free
        connection between modems, saving the start and stop bits.
        This gives at least a 20% increase in throughput.  V42bis adds
        compression, provided that the DTE rate is higher than the
        connection rate.  This means that when downloading a plain text
        (or ASCII) file, it is possible to get faster speeds by
        compressing the data.  The data is compressed so that the same
        information can be encoded in to a smaller space.  The
        receiving modem will of course unscramble the data for you.  If
        news normally flows in at say 200 cps, then, on a 2400 cps
        link, you have up to 44 cps left at the same time for mail,
        telnet'ing, ftp'ing etc.  Compression techniques do not work as
        effectively on binary files and make very little difference to
        pre compressed files (such as .zip, .zoo, .lha etc.).
        Note that MNP5 will usually degrade throughput on an IP link
        due to the packet based nature of it's compression method.
        V42bis does not suffer this problem as it is capable of
        optimising itself dependent on the type of data being
        transferred.
        Now we will discuss the second speed - the speed at which the
        modem and computer communicate with each other.  This is called
        the Data Terminal Equipment (DTE) rate.  If you have a slow
        modem, e.g. a 2400 baud one without MNP or V42, then it will
        probably only work correctly when talked to by the computer at
        the same speed.  For the facts on your particular modem and
        computer you should refer to your manuals.  On faster modems
        you will only be able to take advantage of some of the
        compression features by making the computer talk to the modem
        at a faster speed than modem is talking to the remote modem
        down the telephone line.  Thus you should talk to a 9600 modem
        at 19200 or even 38400.  You should check the maximum speed at
        which the serial port on your modem can talk and then set your
        communication package to work at the highest mutually available
        speed.  Don't forget that without a buffered UART you are
        unlikely to sustain reliable high speed comms above 9600 baud.
        Please note that we only support modems capable of V22bis
        (2400) and upwards.  If you have a US Robotics/Miracom HST
        modem, you may not get very good throughput in HST mode.  In
        practice HST mode is fine if FTP'ing from a site without
        anything else happening (sending mail etc.) as it works fine in
        one direction at a time only.

9. Trouble Shooting

        If you are getting garbled characters on the screen then
        something is wrong!  Garbled characters are often a sign of
        mismatched speeds, lack of handshaking or a non-locked DTE
        rate.  If you get as far as the login prompt but no further
        then make sure that your dialler script is working on 8 bit
        standard comms: 8 bits, no parity, 1 stop bit. See
        /pub/doc/Demon.txt for the full logon script details.
        Having checked your setup according to the information above,
        try reducing the speed at which the computer talks to the modem
        (if using a high speed modem) until the connection works.  If
        you have to do this then either you are attempting to drive
        your computer or your modem at too high a speed, or you have
        other processes running which interfere with the correct
        running of your serial communications (as per Serial Chips
        above).
        If you have finished your live session and log off you may
        sometimes find that your phone line is not dropped.  This can
        result in an unwelcome phone bill!  There are a number of
        computer/software specific solutions to this problem and some
        answers are given in /pub/doc/Support.faq which may have been
        included in your installation.  One thing to check on your
        modem is that the setting that makes the phone line drop when
        the computer tells the modem that it has finished, is on.  The
        computer uses the serial port and drops DTR (Data Terminal
        Ready) and the modem spots this and hangs up the line.  The
        setting often &D2 and you should read the section below which
        tells you how to set this.  It is definitely &D2 for US
        Robotics, SupraFax and Dowty Quattro modems.
        If your modem sometimes seems to fail to recognise a ringing
        tone, reporting it as BUSY.  This can be cured by adding a
        comma after the dial number, e.g. "ATDT0813434848,".  This
        makes the modem pause and ignore the first rings which it
        sometimes things is a busy single.  Some US Robotics modems can
        exhibit this problem.
        ATZ is the command that resets the modem.  Setting your
        initialisation string to ATZA0 etc where A0 is the
        initialisation string is very likely to fail.  This is because
        the modem takes a while to reset and throws away the data being
        sent to it in the meantime.  Some people beg to differ on this
        point.  However it is certainly true on US Robotics modems.
        Just to confuse matters further there are often some switches
        on the modem which you can use to make further settings or to
        default to different options.  These are referred to as DIP
        switches.  Mostly, the advice contained in this document,
        refers to modems that have not had their switches tampered
        with.  If you have the manual for your modem (and I hope you
        have!) then that will probably tell you what the default
        factory switch settings were.  Make a careful note of the
        current settings and then change back to the factory defaults.
        If you already use your modem with other packages, make sure
        they still work.  These DIP switches must be set to ensure that
        the reset command ATZ resets the modem to the stored values.
        On some modems it is possible to make ATZ restore to factory
        settings which rather defeats the object of configuring it!
        Some modems have ATY commands instead of DIP switches and so it
        is important that the correct ATY command has been used.
        Fortunately, the default will ok if no ATY command has been
        issued.
        If you are getting a no response from the modem before dialling
        (eg. The dialler in KA9Q reporting "INPUT LINE WAIT 3000 OK")
        then that means that either your modem is not connected
        properly (check the cables, or for internal modems, check
        jumper settings, and check software configuration to check that
        the dialer is trying to talk to the modem on the correct port),
        or your modem is not configured for verbal result codes.
        Normally the command to accomplish this is ATV1 .
        There is a section below which specifically refers to problems
        that may be encountered by PC users.

10. Software and Other Factors

        By configuring your software correctly you can make significant
        improvements to an under performing communications connection.
        Things to check for include badly fragmented disks (run a disk
        de-fragmenter such as Norton's Speed Disk), no disk cache, no
        or insufficient buffering inside the software and unnecessary
        checking protocols or indexing taking place.  Refer to your
        software's instructions for details on these.

11. Help for Specific Computers

  Some extra comments for some operating systems which may be of use
  follows.
  11.0.     IBM PC Compatibles running DOS
  ========================================
        In addition to the above info there is some specific advice
        below for those of you running DOS.
        Some modems send back "OK" when sent ATZ (the reset command)
        even though they are not ready.  This means that the dialer
        program will try to ring out even though the modem is not
        ready.  The effect is that you will see ATZ on the screen
        followed by OK and then the program will not dial.  Eventually
        it will time out.  To avoid this, send AT instead of ATZ in the
        modem initialisation string.
        Extended memory drivers can interfere with the correct
        operation of your serial communications.  If you suspect this,
        rename your CONFIG.SYS and AUTOEXEC.BAT files and then reboot
        your computer to see if the connection improves.
        If you have a V.32bis 14,400 modem you will probably want to
        talk to it at 38,400.  Unless you have a suitable serial chip
        then you will get errors and, as explained at the start of this
        document, this can seriously impact the throughput.  When
        running NET.EXE you can type asystat at the net> prompt and
        information about your serial comms will be printed to the
        screen.  The interesting parameter is the third one on the
        second line, 'hw over'.  This shows how many hardware overruns
        (characters lost because they weren't fetched from the serial
        chip in time) have occurred.  These overruns are usually due to
        lack of either a buffered UART or hardware handshaking.
        As already stated, for maximum performance you will need to
        have a buffered chip.  For this you will need a 16550A - this
        is the number that is written on the chip.  The asystat command
        will tell you if a 16550 is detected.  Unfortunately, even top
        manufacturers overlook this area so it is quite likely that
        your chip is below par.
        If in doubt, open up your computer and locate the serial chip.
        If it is not a 16550 then it might need replacing.  If you are
        handy with a soldering iron you could replace it, but this is
        not advisable unless you are really confident.  If the chip is
        socketed then it can be removed and a 16550 (costing about #16
        - we sell them) be put in its place.  If not then you could buy
        an extra serial card with a 16550 already on it costing from
        around #30 to #70 depending on the specification.
        Some internal modems use a 16450 with a large buffer (1K) and
        this may be enough to stop hardware overruns.
        If you are using a standard serial port then the settings
        offered for COM1, 2, 3 or 4 in the configuration program in
        DIS.EXE will probably be fine.  Otherwise you should refer to
        your manuals and enter the appropriate IRQ number and I/O base
        address.
        If you install an extra serial card then be aware that if you
        have, for example, a mouse on COM1 then you should not use COM3
        for your modem using the default IRQ setting as they share the
        same interrupt.
        There is another factor that can impede throughput and that is
        software overruns.  Using the NET.EXE software, at the net>
        prompt having just received some news or ftp'd a file, type
        asystat and look at the figure before sw over.  If this is not
        0 then you are getting software overruns.  To fix this,
        increase the buffer size in the attach line near the top of
        autoexec.net:
        attach asy 0x3f8 4 ppp sl0 4096 1500 38400
        Alter the 4096 in the above to be 8192, 12288 or higher until
        the software overruns are cured.
        More information on tuning is available in
        /pub/doc/ka9q/Tuning.faq.
  11.1.     OS/2
  ==============
       If intending to run the DIS DOS software in an OS/2 2.x DOS
       session you should get a copy of sio126c.exe and install the
       communications driver in it before running DIS.  sio126c.zip is
       available on our ftp server or via our guest download account.
       This is because the standard communications drivers do not pass
       to DOS the buffering of your 16550A buffered serial chip.

12. Individual Modem Settings

  12.0.     Setting up a kind of modem not described below
  ========================================================
       To change the settings of your modem, use a program that can
       talk directly to the modem, such as a standard communications
       package.
       (*) In Windows, you can use Terminal (in the Accessories
       Group), setting it for the correct connector (COM Port).
       (*) On the Macintosh, you can use ConfigPPP by switching
       Terminal Window on, and clicking Open.  When you are finished,
       switch off Terminal Window again.
       Type the reset command, usually ATZ <RETURN>, and see the
       response OK.  Then continue through the list of settings.  You
       can type ATI4 <RETURN> or AT&V <RETURN> to see what your
       current settings are on a lot of modems.  For connecting to
       Demon we recommend the following:
       Use V.32bis modulation/CCITT protocols rather than HST
       Originator mode
       Local echo ON
       Duplex OFF; receiving system sends duplicate data
       All result codes displayed
       Display result codes in verbal (not numerical) mode, e.g. OK
       not 0
       Enable additional error control indicator, e.g. LAPM/V42BIS
       Serial port remains at fixed setting
       Modem send CD (Carrier Detect) on connection
       Terminal sends DTR (Data Terminal Ready)
       Data Set Ready (DSR) controlled by the computer
       Hardware CTS (Clear to Send) transmit data flow control
       Received Data h/ware (RTS) flow controlled by computer
       Received Data software flow control disabled (make sure the
               modem uses hardware flow control, and switch off
               XON/XOFF flow control, also known as software flow
               control)
       MNP 5 data compression disabled
       Variable link speed negotiation
       1800Hz UK guard tone on. (Probably AT&G2)
       When done, type the command that saves the settings to Non
       Volatile Ram (NVRAM) (usually AT&W) so that they areremembered
       when the modem is reset.
  12.1.     Setting Up a US Robotics/Miracom Modem
  ================================================
        To set up your modem, use a standard communications package.
        Type ATZ <RETURN> and see the response OK.  Then continue to
        make the settings.  You can type ati4 <RETURN> and ati5 to see
        what your current settings are.  For connecting to Demon we
        recommend the following:
        B0     V.32bis modulation rather than HST
        C1     Transmitter enabled
        E1     Local echo ON
        F1     Duplex OFF receiving system sends duplicate data
        Q0     Result codes displayed
        V1     Display result codes in verbal (not numerical) mode
        &A3    Enable additional error control indicator
        &B1    Serial port remains at fixed setting
        &C1    Modem send CD (Carrier Detect) on connection
        &D2    Terminal sends DTR (Data Terminal Ready)
        &G2    1800Hz Guard Tone
        &H1    Hardware CTS (Clear to Send) transmit data flow control
        &I0    Received Data software flow control disabled
        &K3    MNP 5 data compression disabled
        &N0    Variable link speed negotiation
        &R2    Received Data h/ware (RTS) flow controlled by computer
        &S1    Data Set Ready (DSR) controlled by the computer
        e.g. type AT&K3 <RETURN>.  When done type AT&W <RETURN> to save
        the settings to Non Volatile Ram (NVRAM) so that they are
        remembered when the modem is reset.
       Some US Robotics occasionally mistake a System X (and Y?)
       ringing tone for a busy tone and hang up just as the Demon end
       answers.  Sticking a pause on the end of the dialling sequence
       stops the modem's response long enough for the Demon end to
       start its negotiating sequence.  This means that the confusing
       System X tone is ignored.  If the Demon end is busy you just to
       wait a bit longer for the BUSY string, but not as long as the
       setting in S7.  Add a pause by adding a comma to the end of the
       string.
  12.2.     Apple Express Modem
  =============================
   Just AT&F then AT&C0 to disable compression
  12.3.     BT NS 2232 M
  ======================
       (Note this doesn't work reliably with dial, but does work with
       TIP or with an outboard Kermit script.)
       at &f0 s0=0 x7 m2 &u1 &k0 b0 s30=26 &e5 &r1 &d2 &c1 l3
       &f0 - reset to factory default
       s0=0 - suppress auto answer
       x7 - maximum message generation (for diagnostic purposes)
       m2 - speaker always on, so you can hear retrains
       &u1 - RTS flow control
       &k0 - CTS flow control
       b0 - CCITT mode
       s30=26 - CTS follows DCD **, plus defaults
       &e5 - V.42bis (and LAPM)
       &r1 - RTS locked on (??)
       &d2 - DTR is Data Terminal Ready
       &c1 - CD Normal
       l3 - Speaker loud
  • * the theory is that it would otherwise try to track RTS when

that is used for flow control.

  12.4.     Dowty
  ===============
       Dowty Quantum 144
       To configure this modem for CTS/RTS only (hardware
       handshaking):
       &k2      Use CTS on transmission
       &u2      USE RTS on receive
  12.5.     Dynalink
  ==================
       Dynalink 1414VE: AT&Q9W1S37=11S48=0M0
       &Q9      The modem will attempt V.42bis, fallback to V.42(LAP-
                 M), then fallback to normal mode.
       W1       Reports the error correction protocol and the carrier
                 speed used.
       S37=11   Sets DCE speed (modem to modem) to 14400bps.
       S48=0    Disables protocol negotiation. Forces LAPM.
       M0       Turns off the speaker. (This thing is loud!).
       ATZ or AT&F as the first command as both of these seem to annoy
       the modem into false starts.
       ACTIVE PROFILE:
       B1 E1 L0 M0 N1 Q0 T V1 W0 X4 Y0 &C1 &D1 &G0 &J0 &K3 &Q9 &R0 &S1
       &T4 &X0 &Y0
       S00:000 S01:000 S02:043 S03:013 S04:010 S05:008 S06:002 S07:050
       S08:002
       S09:006 S10:014 S11:095 S12:050 S18:000 S25:005 S26:001 S36:007
       S37:011
       S38:020 S44:003 S46:138 S48:000 S49:008 S50:255
  12.6.     Gateway
  =================
       Gateway Telepath modem: AT&K3s48=0s46=138s36=1
       The modem works fine at 38400 and most of the time is OK with
       14400 carrier. On occasion it works better by setting it down
       to 9600 with n0s37=9 added to the init string.
  12.7.     Global Village
  ========================

From a user: The specs for AT commands for a Global Village PowerPort Silver and Gold modems are as follows: AT {code} command… action…

  \N5 (Set Operating Mode)            Set auto-reliable(V.42 LAPM only)
  \Q3 (Set Serial Port Flow Control)  Enable bidirectionable hardware
                                      flow control
  \J0 (BPS Rate Adjust)               Disable port rate adjust;
                                      serial port rate independent of
                                      the connection
  %C1 (Data Compression)              Enable data compression
                                      (V.42bis in LAPM)

<these following could be helpful…>

  &W1 (Store Active Profile)          Save active configuration as User

Profile 1

  &Y1 (Select Stored Profile On Power Up) Recall User Profile 1 on power up
  &V1 (View Active Configuration and Stored Profile) View profile 1
  12.8.     Mistral
  =================
       For an Amber Logic Mistral FX144 modem.
       Use the factory defaults and the following:
       &E4            Forces the modem to reject the connection with
       the
                      'NO CARRIER' message if it cannot establish a
       V42 link
       S31=2          Locks the DTE baud rate to 38400
  12.9.     Multitech
  ===================
       AT&F
       This just resets to factory settings.
       From one of our users with a Multitech MT1932ZDXK V32Ter and
       fax modem:
       AT&F&E2&E7$MB14400X4M0S0=0
       The X4 just gives you full result codes - not essential unless
       you want to
       know exactly what kind of connection you've got.
       From a Multitech dealer:
       &E4            Hard CTS/RTS
       &BA0           Baud rate altering off
       &E2            V.42 with no fall back to MNP5
       &E15           Compression on
       &D2            Hang up the line when DTR is dropped
  12.10.    Pace Microlin
  =======================
       AT &K3B0E1F0Q0V1%C2&C1&D2\N3
       &K3 - RTS/CTS Handshaking
        B0 - CCITT protocols
        E1 - Enable Echo
        F0 - Negotiate connect speed - may want to use F10 <14.4> if
             saving for use with demon only.
        Q0 - Enable result codes
        V1 - Verbose result codes
       %C2 - V42 but no MNP5 compression
       &C1 - DCD follows carrier
       &D2 - hang up on DTR
       \N3 - Autoreliable link - use \N2 to reject links negotiated
             without error correction.
       AT &W to save as default, or AT &W1 to save in second NVRAM
       section for recall with ATZ1 as modem initialisation string.
  12.11.    Pace Mobifax
  ======================
       For connecting to Demon we recommend the following:
       Command   What it does
       B0        Use V.32bis modulation/CCITT protocols rather than
       HST
       &C1       Modem send CD (Carrier Detect) on connection
       E1        Local echo ON
       F0        Variable modem-to-modem speed negotiation
       Q0        All result codes displayed
       V1        Display result codes in verbal (not numerical) mode,
       e.g. OK not 0
       X4        Gives full CONNECT string
       &D2       Terminal sends DTR (Data Terminal Ready)
       &S1       Data Set Ready (DSR) controlled by the computer
       &K3       RTS/CTS flow-control
       When done, type the command that saves the settings, AT&W, so
       that they are remembered when the modem is reset.
  12.12.    Racal
  ===============
       From a user:
        My modem is a model Racal Maxam V 9600 baud, about 2 years
        old.I have been told that a Racal connected to a US Robotics
        the Racal can detect a higher baud carrier as its own 9600
        carrier.When connected you will get lots of 8bit characters
        and the modem will then drop the line.This can be solved by
        forcing the modem to 9600 and not checking for errors at this
        baud rate.
       The command string is atn0f8&e0&w0 for a Racal:
       n0      - Do not seek the baud rate
       f8      - Force baud to 9600
       &e0     - No error check
       &w0     - Write change
  12.13.    Rockwell chipset modems
  =================================
       Rockwell chipsets are used in a variety of modems, namely Supra
       and SmartOne.
       B0  v32bis modulation
       E1  Local echo on
       V1  Word response for errors
       Q0  Modem sends responses
       F1  Duplex off. (Can't find any not to)
       &A3
       &S1
       There is an "undocumented" feature present in the Supra
       V.32/V.32bis FAX Modems that can help improve the quality of
       FAX and Data transmissions.
       The AT\E1 command is not documented in Supra's manuals, but is
       present in the Rockwell V.32/V.32bis firmware/chipsets on which
       the Supra V.32/V.32bis FAX Modems are based. This command is
       documented in the RC96AC and RC144AC Modem Designer's Guide
       from Rockwell International.
  12.14.    SmartOne
  ==================
   (also badged Best Data, CalCom)
       &F      Restore factory settings
       B0      Select CCITT V.22 and V.21 mode
       C1      Normal transmit carrier switching
       E1      Command character echo enabled
       F1      On-line state character echo disabled
       Q0      Result code messages sent to machine
       V1      Result code messages sent in English word format
       &C1     DCD indicates on-line data carrier detected
       &D2     Modem disconnects when DTR drops
       &G2     1800 Hz Guard Tone
       &K3     Enable CTS/RTS flow control
       &Q6     Select Asynchronous operation in normal mode
       &R0     CTS follows RTS
       &S1     DSR turned off while carrier is lost
       \G0     Disable Xon/Xoff flow control
       For v32bis (14,400 baud) models:
       S37=11  Attempt to connect at 14400 bps
  12.15.    Supra modems
  ======================
        Supra 14.4k fax modems need the ROM revision 1.70B or later but
        their ROM revision number is odd.  Revision 1.8 or 1.4 are also
        apparently OK.
        Information providing features
            Enable all CONNECT, PROTOCOL & COMPRESSION mesgs:   s95=41
            loudspeaker control (low volume, on until carrier): l1m1
        Modem/PC signals
            modems disconnects when DTR drops:                  &d2
            DCD follows line carrier:                           &c1
            Enable hardware flow control:                       &k3
        Speed connection, reject bad lines
            new models, only make LAPM Reliable connections:    \n4
            old models, make AutoReliable connections:          \n3
            Disable negotiation, make V42 (LAPM) connection:    s48=0
            connect at highest shared data rate:                n1
        Compression
            new models, V.42bis (BTLZ) Enabled, (but not MNP):  %C2
            old models, enable data compression (BTLZ or MNP):  s41=1
        An initialisation string for this would be:
        ats95=41 l1m1&d2&c1&k3 \\n4 s48=0 n1 %C2
                         ^note the double '\' is needed if typing this
                         into some dialer programs
        To put this into the modem's memory (NVRAM) type at&w
  12.16.    Yoriko modems
  =======================
        Yorikos work OK with a simple AT&F&C1&D2 set-up.
  12.17.    Zoltrix
  =================
       These are one of our user's settings for a Zoltrix v32bis
       internal fax/modem.  He writes:
       With X4, W1 and V1, I've managed to configure it very nicely to
       redial if the line's are busy after only 5 seconds, report
       CONNECT, PROTOCOL CARRIER, and BUSY
       The only bit I'm vaguely unsure about is, whether disabling
       compression (%c0 on mine), disables v42bis also, as I really
       only want to knock out MNP 5. &Q9 I think attempts v42bis,
       falls back to LAP-M+v42, then to normal.
       An annoying feature is that at&v only digs out probably a
       quarter of the settings - the '\' and '%' commands don't
       feature; some of them appear extremely useful: %Q for instance
       purportedly reports line signal quality, and %L received signal
       level, which I reckon might be relevant to one recent spate of
       postings, and you can tune up v42bis with others.
       S86 stores a connection failure cause code.
       OK
       at&v
       ACTIVE PROFILE:
       B0 E1 L0 M0 N1 Q0 T V1 W1 X4 Y0 &C1 &D2 &G0 &J0 &K3 &Q9 &R0 &S1
       &T4 &X0 &Y0
       S00:000 S01:000 S02:043 S03:013 S04:010 S05:008 S06:002 S07:060
       S08:002 S09:006
       S10:014 S11:095 S12:050 S18:000 S25:005 S26:001 S36:007 S37:000
       S38:020 S44:003
       S46:138 S48:007 S49:008 S50:255
       Another user writes:
       Rom revision (use ATI0 or similar to check) : See below
       AT&Q5S48=7S46=138S95=46
       Rom revision
       ------------
       I have listed what comes out of ATI0 to ATI4 as ATI0
       doesn't make sense!
       ATI0 = 14400
       ATI1 = 007
       ATI2 = OK
       ATI3 = V1.410-AP39
       ATI4 = a007880284C6002F
              bC60000000
              r1005111151012004
              r3000111170000000
       Additional modem string info. (may be of some use)
       &Q5    = set error correction mode
                causes the modes to try v42bis, then MNP5, then normal
                connection
       S48=7     = enable V42 negotiation
       S46=138   = error correction with compression
       S95=46      = display extended result codes
                so I can see that i've got error correction
                and compression :-)
       I also have a line
       echo atz > com3:
       in my demon.bat file to reset my modem as my fax software
       leaves it in a bit of a state :-(  Two 'init' lines don't seem
       to work (not that I'm bothered!)
       Yet another user writes:
       This might be helpful if anyone calls using a Zoltrix 28800/
       Internal / Fax.
       Setup straight from box, using a comms package.
       Using factory settings, AT&F,
       then alter s7 to = 20   ATS7=20
       then alter b1 to b0     ATB0
       then alter &q6 to &q5   AT&Q5
       optional  ATL1 to ATL2  ATL2 - modem volume to hear connect.
       and then write these to the stored profiles
       AT&W0
       AT&W1
       Software used:
       Windows 3.11 for workgroups
       MS-Dos 6.22
       DISWIN.EXE from Demon
       DIS216C.EXE  "     "
       Cybercom.drv - from ftp.qualcomm.com (can't rem exact loc)
       to replace standard comm.drv, supports higher speed 57600+
       rather than 19200
       In windows system.ini under 386Enh
       Com*fifo=1
  12.18.    Zoom modems
  =====================
       From one user comes this:
                      Zoom 14.4X FaxModem Settings
                      ============================
       These setting are in use to connect to demon both via KAQ9 and
       trumpet winsock (SLIP). The settings enable 14400 bps with V42
       error correction and V42bis data compression. In operation I
       achieve 2600 cps when obtaining mainly text news. Whilst I am
       sure the settings work I do not vouch for the accuracy of my
       interpretation of what they mean!!
       To reset modem to stored profile:-
       ATZ      - sets to profile 0
       ATZ0     - sets to profile 0
       ATZ1     - sets to profile 0
       To store current profile:-
       AT&W0    - store as profile 0
       AT&W1    - store as profile 1
       For brevity I have left out setting that have no functional
       relevence.
       Profile     Command      comments
       E1          ATE1         Command characters echoed
       N0                       *ATN0 (zero)   Disable auto-mode
                                 detection; connection speed specified
                                 by register S37
       Q0          ATQ0 (zero)  Enable response to computer (DTE)
       X3                       *ATX3     Monitors busy tones; sends
                                 X2 messages
       Y0          ATY0 (zero)  Disable long space disconnect
       &C0         AT&C0 (zero) Forces RLSD (DCD) on
       &D0         AT&D0 (zero) Data terminal ready options
       &G2         *AT&G2       Enable 1800Hz guard tone
       &J0         *AT&J0 (zero)Disable adjusting DTE speed
       &K3                      AT&K3     Enable RTS/CTS flow
                                 control. VITAL for slip connections
                                 such as Trumpet winsock
       &R1                      AT&R1     CTS is always on in
                                 synchronous or drops if required by
                                 flow control in asynchronous
       &S1*                     AT&S1     DSR active after answer
                                 tone detected and inactive after
                                 carrier loss.
       &T4                      AT&T4     Responds to remote modem
                                 request for digital loopback.
       Registers
       Set using ATSn=v  Sets register n to value v
       S37 11 *
       All lines with an * are for items than are altered fron the
       factory default settings.
       We would recommend &d2 otherwise your modem may not hang up the
       line when you have finished your call.
       From yet another user: The best I've got so far for the Zoom
       14.4X is AT&F0W0&C1&D2%C2
       &F0 (manufacturer's defaults, so we know where we are)
       W0 (limit the messages coming from the modem)
       (W1 gives lots of messages from the modem but causes problems
       for some people)
       &C1&D2 (for hardware flow control)
       %C2 (enable V42 bis but not MNP5)
  12.19.    Zyxel
  ===============
       From one of our users again:
       The following "dial_cmd" is for a Zyxel U-1496E+ modem
       "ATL2N1X7&G2*E1DT"
       L2 --- sets a low (but not inaudible) speaker volume
       N1 --- sets a low (but not inaudible) ringing volume
       X7 --- sets result code options so that the "connect" message
       is, for example, "CONNECT 14400/Arq/V42b"
       &G2 -- enables 1800 Hz guard tone
       *E1 -- terminate call if error control negotiation fails, ie.
       insist on error-control or end call
       DT --- dial using DTMF tones

13. Testing

        To test out your setup you could try using ping.  ping
        gate.demon.co.uk whilst logged on directly to gate should
        return a speed of about 270ms on a fast link down to 1000ms on
        a slow link.
        Try using ftp to ftp.demon.co.uk and downloading files from
        /pub/test.  There are files of varying contents that have also
        been compressed in various ways.  "empty" files are there so
        that you can test the maximum throughput on blank data.  "full"
        files contain a thorough mix of characters and so little
        compression by your modem will be possible. "regular" files are
        a mixture - just like this document or a Usenet news message.
        Each of these three have been compressed using popular methods
        and so you can try working on the compressed files as well if
        you like.  Try uploading these files to
        ftp.demon.co.uk:/incoming to test the link in that direction as
        well.
        Using a V.32bis modem, the maximum throughput you are likely to
        get on a binary file is 1,600 cps.  On an ASCII file the
        maximum is about 2,800 cps.

14. Finally

        Please try to sort out your setup by following the above
        advice.  If you are still stuck then telephone the support line
        on 0181-371 1010 during support hours to see if further help
        can be offered.  Full support line details are available in
        /pub/doc/Welcome.txt.
/data/webs/external/dokuwiki/data/pages/archive/internet/modem.txt · Last modified: 2000/11/18 16:51 by 127.0.0.1

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