Re: Questions about ModemManager

[Tambet Ingo <tambet gmail com>]

On Fri, Sep 25, 2009 at 12:50, Ozan Çağlayan <ozan pardus org tr> wrote:
> 1. After calling Connect() and using PPPD to create a PPP connection
> through a modem, how should I cleanly disconnect from device? I first
> terminate PPPD and then call Disconnect() over D-Bus but after that I'm
> having serial connection timeouts over MM if I recall Connect() a second
> time. What's the purpose of Disconnect()? Should it be used? It doesn't
> seem to send some AT commands at all as the --debug output of MM stays
> intact after Disconnect() calls.

Disconnect() can't send any AT commands, the device is in use and
doesn't accept any commands. MM instead sets the sport speed to 0 bps,
just like other terminal handling programs do. I suspect pppd does the
same thing, so it doesn't really matter whether you terminate pppd or
call Disconnect(), the result should be exactly the same. It might be
a good idea to call Disconnect() too, in case pppd segfaults on
shutdown or something.

>
> 2. What does 'No cause information available' means?
>
> ** (modem-manager:7311): DEBUG: (ttyUSB0): <-- '<CR><LF>+CME ERROR:
> 11<CR><LF>'
> ** (modem-manager:7311): DEBUG: Got failure code 11: SIM PIN required
> ** (modem-manager:7311): DEBUG: (ttyUSB0): --> 'AT+CFUN=1<CR>'
> ** (modem-manager:7311): DEBUG: (ttyUSB0): <-- '<CR><LF>OK<CR><LF>'
> ** (modem-manager:7311): DEBUG: (ttyUSB0): --> 'AT+CSQ<CR>'
> ** (modem-manager:7311): DEBUG: (ttyUSB0): <-- '<CR><LF>+CME ERROR:
> 11<CR><LF>'
> ** (modem-manager:7311): DEBUG: Got failure code 11: SIM PIN required
> ** (modem-manager:7311): DEBUG: (ttyUSB0): --> 'AT+CPIN="****"<CR>'
> ** (modem-manager:7311): DEBUG: (ttyUSB0): <-- '<CR><LF>OK<CR><LF>'
> ** (modem-manager:7311): DEBUG: (ttyUSB0): --> 'AT+CSQ<CR>'
> ** (modem-manager:7311): DEBUG: (ttyUSB0): <-- '<CR><LF>+CSQ:
> 13,99<CR><LF><CR><LF>OK<CR><LF>'
> ** (modem-manager:7311): DEBUG: (ttyUSB0): --> 'ATDT*99#<CR>'
> ** (modem-manager:7311): DEBUG: (ttyUSB0): <-- '<CR><LF>NO CARRIER<CR><LF>'
> ** (modem-manager:7311): DEBUG: Got failure code 3: No carrier
> ** (modem-manager:7311): DEBUG: (ttyUSB0): --> 'AT+CEER<CR>'
> ** (modem-manager:7311): DEBUG: (ttyUSB0): <-- '<CR><LF>+CEER: No cause
> information available<CR><LF><CR><LF>OK<CR><LF>'

+CEER command is supposed to return the reason why dial command
failed. Your modem has no idea why it failed.

> 3. What does Enable() exactly do on the device?

It does whatever is necessary to turn your modem on so that it is
ready for use (registration).

Tambet