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  1. #1
    Simon Long
    Guest
    Hi All,

    This problem seems to be widely acknowledged, but I was wondering if
    anyone who knows a bit more about AT commands and the like than I do
    can suggest a solution.

    There is a known problem with sending large (>10k) files via a Nokia
    6310i over IrDA from a Psion 5mx PDA. Basically, the phone connection
    to the ISP is dropped randomly when sending large amounts of data.
    (Receiving data is fine.)

    I have recently been forced into using a 6310i (my Ericsson R520 died)
    and this problem is really bugging me. There are numerous solutions
    suggested online, mostly involving switching to XON/XOFF flow control,
    but these don't seem to work. Similarly, using the Mobile Connectivity
    Updates from Psion are supposed to help, but they don't.

    I have seen this problem with 2 different Psions and 3 different
    6310i's. It does not happen when using the Nokia PC Suite to connect
    to the phone via IR from a laptop, and it does not happen when using
    the Psion to connect to an Ericsson phone. Hence there is some
    incompatibility between the Psion and the Nokia.

    Looking at the Psion's comms log file, I have noticed something. The
    last commands before the call ends (which are logged) are usually
    something along the lines of :

    Tx:AT
    Rx:
    OK

    Tx:ATO
    Rx:
    NO CARRIER

    Tx:ATH
    Rx:
    OK

    Now, from reading some of the documentation on the web, it looks as if
    the Psion has got into a mode where it has issued (or thinks it has
    issued) an escape sequence ('+++') to the Nokia - ATO is the command
    to return to online mode after an escape.

    What I suspect is happening is that the Psion issues an escape command
    to the Nokia, and somehow by the time it is ready to return to online
    mode, the Nokia has disconnected. The question is why the Psion is
    issuing excapes while in the middle of sending data - under what
    circumstances will this happen? AT commands are used to configure the
    modem, and I would have assumed that once connected, this shouldn't be
    necessary. Are XON/XOFFs sent via escape sequences? Is there some way
    of stopping the Psion from sending escapes? What does the Psion think
    it is doing while in command mode? Is it sending some AT command which
    hangs-up, or which is interpreted by the Nokia as a hang-up request?

    I don't know if this is fixable - I'm sure Psion aren't interested in
    fixing it, and I doubt that Nokia care that much. I'm wondering if
    some judicious hacking of the GSMBSC.TSY telephony stack on the Psion
    with a hex editor could change a command sequence to stop this, but I
    don't know enough about modem command sets to know where to look.

    Any advice gratefully received - please post to the group if you have
    any ideas.

    Simon



    See More: Uploading data from a Psion via a Nokia 6310i - problems.




  2. #2
    Simon Long
    Guest

    Re: Uploading data from a Psion via a Nokia 6310i - problems.

    (Apologies for not following the thread correctly - Google Groups
    seems a bit slow this morning....)


    "Chris Malcolm" <[email protected]> wrote in message
    news:[email protected]

    > I tried sending some large files from my Psion 5mx via infrared and
    > the Comms App to my office computer via a 6310i. YMODEM, which works
    > fine the other way, dropped out at first 10K for some reason. But it
    > also does this when connected via data cable. So I tried plain ASCII,
    > and transferred several 1/3 Megabyte files by infrared successfully
    > with no problem. Incidentally, I noticed that speed of transfer varied
    > noticeably with mobile signal strength.


    That's interesting. I hadn't tried any plain ASCII, but if that gets
    through ok, then it is probably a problem with data bytes in the
    transmitted file being interpreted as control codes which cause the
    connection to drop. I've read recently in some modem documentation
    that XON/XOFF flow control is not recommended when sending binary
    data. I would have thought that the protocol was designed to cope with
    this, but maybe it isn't...

    > Can you be more specific about the circumstances of your problem? I
    > seem to recall there was some strange interaction with another
    > apparently completely unrelated Psion 5mx parameter which when set
    > appropriately made this infrared dropout problem go away.


    OK. I am using RMRFTP to upload files to my website. I am using HSCSD
    on Orange (although turning that off doesn't seem to make any
    difference). I have tried lots of different setups on the Psion, but
    the one I have settled on as being least bad (!) is :

    Speed : 115200
    Connect : Infrared
    Fax Class : Auto
    Init string : AT&F&K4 (factory defaults, XON/XOFF flow control)
    Data string : AT+CBST=14
    Flow control : Software
    DSR : Not checked
    DCD : Not checked
    Modem : Mobile

    This works fine for downloads, but uploads tend to fall over after 25k
    or so. On occasion something gets through - I am testing with a 75k
    SIS file - but it probably works no more often than 1 time in 20.

    I have tried nFTP - same problem.

    If I enable connection logging (C:\Logs\Etel), the file shows all the
    initial handshaking as fine, up to a good CONNECT string. The last few
    lines in the file tend to show something like :

    Tx: AT
    Rx:
    OK

    Tx: ATO
    Rx:
    NO CARRIER

    Tx: ATH
    Rx:
    OK

    This looks to me as if the Psion has sent an escape sequence to the
    phone at some point, and the line gets dropped while the Psion is
    offline.

    On occasion, you actually see the Psion send the escape in the log
    file - something like :

    Tx: AT
    Tx: +++
    Tx: AT
    Tx: AT
    ERROR

    I have tried dropping the connection speed between the Psion and the
    phone, and changing the flow control, but nothing seems to affect what
    happens.

    I have read that there are problems with IrDA if the Psion's
    auto-power down timeout is set to > 30 minutes, but it is set to 3
    minutes on mine.

    Any bright ideas - I'm stumped! (As are Psion Teklogix - I'm tempted
    to try and extract the GSM files from the latest ROM for the Netbook,
    as the readme admits to a bug in Etel being fixed. It'd be interesting
    to know if any Netbook users can get this to work...)

    Cheers,

    Simon

    I



  3. #3
    =?ISO-8859-1?Q?Mark=B2?=
    Guest

    Re: Uploading data from a Psion via a Nokia 6310i - problems.

    Simon Long wrote:
    > Hi All,
    >
    > This problem seems to be widely acknowledged, but I was wondering if
    > anyone who knows a bit more about AT commands and the like than I do
    > can suggest a solution.
    >
    > There is a known problem with sending large (>10k) files via a Nokia
    > 6310i over IrDA from a Psion 5mx PDA. Basically, the phone connection
    > to the ISP is dropped randomly when sending large amounts of data.
    > (Receiving data is fine.)
    >

    <snip>

    > Are XON/XOFFs sent via escape sequences? Is there some way
    > of stopping the Psion from sending escapes? What does the Psion think
    > it is doing while in command mode? Is it sending some AT command which
    > hangs-up, or which is interpreted by the Nokia as a hang-up request?
    >
    > Simon


    Have you tried to change the flow control to RTS/CTS, AT command &K3
    - this is usually works best in "normal" PC communications.

    --

    MarkČ
    Linux Registered User #324341




  4. #4
    John Henderson
    Guest

    Re: Uploading data from a Psion via a Nokia 6310i - problems.

    "Simon Long" wrote:

    > I've read recently in some modem documentation that XON/XOFF
    > flow control is not recommended when sending binary data. I
    > would have thought that the protocol was designed to cope with
    > this, but maybe it isn't...


    Software flow control (using the XON/XOFF characters) cannot be
    used reliably for binary data, as these two characters are very
    likely to occur within the data itself. They will be
    interpreted, and lost from the data stream, instead of being
    passed transparently. Other things being equal, a single XOFF
    will terminate data transfer.

    Hardware flow control (using the CTS/RTS RS232 pins) is the
    sensible strategy where binary data might be involved.

    The real advantage of XON/XOFF flow control is that it can be
    used over a simple 3-wire circuit (on long runs between buildings
    for example).

    John





  5. #5
    Chris Malcolm
    Guest

    Re: Uploading data from a Psion via a Nokia 6310i - problems.

    [email protected] (Simon Long) writes:

    >Hi All,


    >This problem seems to be widely acknowledged, but I was wondering if
    >anyone who knows a bit more about AT commands and the like than I do
    >can suggest a solution.


    >There is a known problem with sending large (>10k) files via a Nokia
    >6310i over IrDA from a Psion 5mx PDA. Basically, the phone connection
    >to the ISP is dropped randomly when sending large amounts of data.
    >(Receiving data is fine.)


    I tried sending some large files from my Psion 5mx via infrared and
    the Comms App to my office computer via a 6310i. YMODEM, which works
    fine the other way, dropped out at first 10K for some reason. But it
    also does this when connected via data cable. So I tried plain ASCII,
    and transferred several 1/3 Megabyte files by infrared successfully
    with no problem. Incidentally, I noticed that speed of transfer varied
    noticeably with mobile signal strength.

    Can you be more specific about the circumstances of your problem? I
    seem to recall there was some strange interaction with another
    apparently completely unrelated Psion 5mx parameter which when set
    appropriately made this infrared dropout problem go away.


    --
    Chris Malcolm [email protected] +44 (0)131 650 3085 DoD #205
    School of Informatics, Edinburgh University, 5 Forrest Hill,
    Edinburgh, EH1 2QL, UK. [http://www.dai.ed.ac.uk/homes/cam/ ]



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