Re: ttyUSB* device for ModemManager


Network Manager was picking the correct interface 3.

From /proc/bus/usb/devices, I found that interface 2 shows null and so /dev/ttyUSB3 was not created from the USB subsystem it self.

Even in windows It does not create virtual com port for interface 2.

And it works fine in my Liunx.

Thanks for you prompt reply and My apologize for delay in reply.


On Thursday 01 December 2011 05:12 AM, Dan Williams wrote:
On Fri, 2011-11-25 at 00:45 +0530, TechnoStab wrote:
Thanks Dan,

I am using ZTE MF100 3g modem. I can see udev rules for the same modem
in /lib/udev/rules.d/77-mm-zte-port-types.rules.

ATTRS{idProduct}=="0031", ENV{.MM_USBIFNUM}=="03",
ATTRS{idProduct}=="0031", ENV{.MM_USBIFNUM}=="01",

  From the log, modem manager obtains two usb ports /dev/ttyUSB1 and
/dev/tyUSB2 but /dev/ttyUSB3 does not exist that it should be.

As you said, from windows its very easy to figure out what interface is
being used by modem and it also shows it's 3.
Do you happen to have the Windows drivers for the MF100 so I can take a
look at the INF files?



On Tuesday 22 November 2011 01:34 AM, Dan Williams wrote:
On Mon, 2011-11-21 at 15:13 +0530, Jaymin Patel wrote:


I am using modem that is not detected as /dev/ttyUSB0 instead its
detected as /dev/ttyUSB1. Want to know how ModemManager selects
ttyUSB* device for Mobile Broadband connection.

MM selects the first port that passes probing as the main port (except
for Huawei modems where it always uses USB interface 0), unless it's
been "tagged" according to the udev rules.  Some modems only allow PPP
on specific USB interfaces, and for those we have to find the Windows
driver and look at the .INF files for which interface is supposed to be
the "modem" or PPP interface.  Note that USB interface numbers don't
directly correspond to the X in ttyUSBx (or ttyACMx).

What modem is it that you're having trouble with?  It may be as simple
as getting the Windows driver and figuring out what the port mapping is
supposed to be.


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