Re: modems using same port for data & AT command

[Dan Williams <dcbw redhat com>]

On Wed, 2011-04-27 at 09:31 +0300, Ran Shalit wrote:
> 
> 
> On Tue, Apr 26, 2011 at 10:16 PM, Marcel Holtmann
> <marcel holtmann org> wrote:
>         Hi Ran,
>         
>         > > > I am using a device with one port for both data and
>         connection (MC950D
>         > > > novatel), and it is interesting that after connecting
>         with kppp I can see
>         > > in
>         > > > the kppp properties (after pressing "details" button) a
>         window of "kppp
>         > > > statistics", which shows number of transmit/received
>         packets. does it
>         > > mean
>         > > > that the kppp send AT command while in ppp connection ?
>         > >
>         > > the second port of the MC950D is by default in QCDM mode.
>         You can send
>         > > AT$NWDMAT=1 to the first AT command channel and turn the
>         second TTY also
>         > > into an AT command channel.
>         >
>         
>         >  I did not find in the MC950D datasheet that it has any
>         second port, which
>         > you said as being used for QCDM.
>         > Where did you read about it ?
>         
>         
>         don't remember, but my MC950D shows up with two TTY devices.
>         
>         > > Network statistics are a different story - you're not
>         querying the modem
>         > > for those; you're querying the ppp interface. The Linux
>         kernel keeps track
>         > > of the network flowing over that interface. If you run
>         'ifconfig', you'll
>         > > likely see ppp0 as a network interface, complete with
>         statistics.
>         > >
>         > >
>         > >
>         > If the statistics can be queried from the ppp interface, it
>         gets me closer
>         > to the idea that AT commands are not used while in ppp
>         connection, but I
>         > now see that this device (MC950D ) can send/recieved SMS
>         message (which I
>         > think is only done using AT command). I see that in the
>         Mobilink application
>         > (which is used with the MC950D in windows), and I also tried
>         it and it
>         > works.
>         
>         
>         You really want the second AT command channel for network
>         status updates
>         and especially if you wanna do extra things like SMS sending.
>         
>         Regards
>         
>         Marcel
>  
> Hello,
>  
> You were right that MC950D has two ports and one can be used for data
> while the other can be used for control. It is strange that such thing
> was not documented anywhere. 

ModemManager should be flipping the second port over to AT modem when it
probes the modem.  That should be the case for any Novatel GSM device.
Is that not happening?

Dan