pppd hangs: problem found and solved (almost)

Discussion in 'Linux Networking' started by dubal, Aug 7, 2005.

  1. dubal

    James Knott Guest

    At the time dialup modems became popular, a lot of devices didn't use
    hardware handshaking. In fact, if you look at the history of data
    terminals, xon/xoff, were user commands to the host, to pause printing or
    display.
     
    James Knott, Aug 8, 2005
    #21
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  2. A nit, but are you sure about that? I haven't used a Courier or
    read a manual I know is specific to it. But I've been told, by
    someone I've come to trust, that the USR Sportster AT&F turns off
    all flow-control.

    The only USR document I have is a PDF downloaded 3 years ago that
    appears to be a general USR V90 quick reference manual. It shows the
    configuration for AT&F as "Generic," AT&F1 as "Hardware flow-control",
    and AT&F2 as "Software flow-control," so a reasonable conclusion
    would seem to be that "Generic" means "No flow-control."
     
    Clifford Kite, Aug 8, 2005
    #22
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  3. Sigh. No, I meant the OP. (If the remark is directed to me. :/)
    But there is such a thing as an inappropriate factory default setting,
    nicht wahr? Inappropriate in the sense that almost no one uses it.

    Has anyone else noticed how ridiculous this thread has become. ;-}
     
    Clifford Kite, Aug 8, 2005
    #23
  4. dubal

    James Knott Guest

    I have the USR Courier manual in front of me. There is no &F command, but
    &F0 is no flow control, &F1, hardware flow control and &F2, software.
     
    James Knott, Aug 8, 2005
    #24
  5. dubal

    James Knott Guest

    According to my Courier manual, the default is auto answer off.
     
    James Knott, Aug 8, 2005
    #25
  6. dubal

    Unruh Guest


    On the Sportster, F0 and F is software and F1 is hardware. What a silly
    decision.
     
    Unruh, Aug 9, 2005
    #26
  7. dubal

    Moe Trin Guest

    In the Usenet newsgroup comp.os.linux.networking, in article
    Let me join the others - I STRONGLY disagree. Besides, have you looked
    at the modem manuals and verified that the ATZ does what you think it does?
    Heres the section straight out of a USR modem from the internal help (AT?
    command):

    Zn n=0 Dip #7 up: Yn
    Dip #7 down: &F0
    n=1 Reset to &W0 settings
    n=2 Reset to &W1 settings
    n=3 Reset to &F0 settings
    n=4 Reset to &F1 settings
    n=5 Reset to &F2 settings

    and the manual EXPLICITLY RECOMMENDS AT&F1 in several places. Notice that
    ATZ (implies ATZ0) does not necessarily do what you think it might. It
    depends on BOTH the Dip switch setting (on an internal, this is hardwired
    to "up") and the value set with the ATY command, which is...
    Care to explain that?
    Care to explain how you tell the modem that this is needed? (HINT: It's
    not a Hayes command or switch setting.)
    Virtually all applications that use the modem can do so - and on rare
    occasions, they even try to send something sensible.

    Old guy
     
    Moe Trin, Aug 9, 2005
    #27
  8. dubal

    James Knott Guest

    Why do you say that?
     
    James Knott, Aug 9, 2005
    #28
  9. That is missing the point. The only thing provided by a factory setting
    is a known starting point, which for that modem will *always* *be* *the* *same*.

    Exactly what it is, makes no difference because you are then going to
    change it anyway.
     
    Floyd L. Davidson, Aug 9, 2005
    #29
  10. Wouldn't "&F" be the same as "&F0"?
     
    Floyd L. Davidson, Aug 9, 2005
    #30
  11. Hi there


    I was referring to the modems' default, not the app's default.
    Could you be more specefic.
    Not shielding stuff may cause interference.
    So you assmued that TVs are the only appliences I ever opened.
    A power cycle is not the same thing as a dip.
    Slowly increase the mains voltage from 0 to a normal value and look
    which devices actually boot.
    Most POR cirquits aren't designed to deal with this situation. Even
    though the mains voltage will occasionly drop to a low level and then
    slowly rise.
    Nothing.
    You brought it up.


    Regards,
    Rob
     
    Rob van der Putten, Aug 9, 2005
    #31
  12. Hi there


    You may be right.


    Regards,
    Rob
     
    Rob van der Putten, Aug 9, 2005
    #32
  13. Hi there


    AFAIK it is.


    Regards,
    Rob
     
    Rob van der Putten, Aug 9, 2005
    #33
  14. Hi there


    On a Courier it is off.
    I have got an old 14k4 which has an auto answer default.


    Regards,
    Rob
     
    Rob van der Putten, Aug 9, 2005
    #34
  15. Hi there


    A lot of modems have more then one ATZ / AT&W.
    And a lot have dip switches.
    I was referring to &W0, ATZ0 and the factory default dip switch
    settings.
    Does an auto answer factory default make sense?
    These and the com port speed can be detected automatically by analyzing
    "AT".
    If you then do an AT&W (or AT&W1), the modem will store these as
    defaults.
    Obviously.


    Regards,
    Rob
     
    Rob van der Putten, Aug 9, 2005
    #35
  16. dubal

    James Knott Guest

    I didn't see "&F" mentioned in the manual, only "&F0". I haven't tried, to
    see if "&F" works. If it's not in the manual, I don't assume it's
    available.
     
    James Knott, Aug 9, 2005
    #36
  17. dubal

    James Knott Guest

    Not on my Courier.

    From the manual re the S0 (auto answer) settings.

    "Default: See DIP Switch 5" and "Function: Sets the number of rings on
    which to answer when in Auto Answer mode. SO=0 disables Auto Answer, the
    same as DIP switch 5 ON (factory setting). SO=1 enables Auto Answer and
    the modem answers on the first ring."

    Also, according to the DIP switch settings, switch 5 is on by default, which
    disables auto answer. So my Courier defaults to auto answer off.
     
    James Knott, Aug 9, 2005
    #37
  18. Hi there


    It's not a 14k4 Courier (do they exist?).
    It's more like a no name Tornado clone.

    Regards,
    Rob
     
    Rob van der Putten, Aug 9, 2005
    #38
  19. Hi Moe-
    I wondered about that too. One Hayes FAQ implies the modem obtains the
    device file bits-parity-stopbits setting (somehow) whenever it sees the
    AT (or at) which precedes all modem commands. I assume the modem finds
    that setting in the Line Control Register of the serial device's UART.

    Comments or corrections are welcome.
     
    Clifford Kite, Aug 9, 2005
    #39
  20. dubal

    James Knott Guest

    My V.90 Courier was originally 14.4K (IIRC), prior to the free daughter
    board upgrade.
    It's definitely a USR Courier. It's right in front of me. The manual also
    says USR Courier. I bought it about 13 - 14 years ago, when they were
    still expensive.
     
    James Knott, Aug 9, 2005
    #40
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