Single RS232 port Telit and CMUX mode (GSM 27.010 / n_gsm)

[Tim Small]

On 04/07/17 09:58, Aleksander Morgado wrote:

> Given this is a pure RS232 device, there's not much "auto-probing" we
> can do, unless as Dan says there's a clear way to link both ports to
> the same "physical device" via udev properties or what not. Could you
> run udevadm info again using --attribute-walk in both gsmttyX devices?

~# udevadm info -a /sys/devices/virtual/tty/gsmtty1

Udevadm info starts with the device specified by the devpath and then
walks up the chain of parent devices. It prints for every device
found, all possible attributes in the udev rules key format.
A rule to match, can be composed by the attributes of the device
and the attributes from one single parent device.

  looking at device '/devices/virtual/tty/gsmtty1':
    KERNEL=="gsmtty1"
    SUBSYSTEM=="tty"
    DRIVER==""


... so there isn't by the look of things.


> 
> Anyway, you can manually "force" both TTYs to be part of the same device by assigning to both the same "uid" in the ID_MM_PHYSDEV_UID udev tag; e.g.:
> 
>   DEVPATH=="/devices/virtual/tty/gsmtty0", ENV{ID_MM_PHYSDEV_UID}="muxed"
>   DEVPATH=="/devices/virtual/tty/gsmtty1", ENV{ID_MM_PHYSDEV_UID}="muxed"
> 
> (only if using ModemManager git master)
> 
> Then you would also be able to use the "uid" in mmcli calls, e.g. "mmcli -m muxed --simple-connect", btw.

That's working well - thanks very much.

I seem to be having some trouble with the primary line getting stuck
connected when mm doesn't think it is, which I'm trying to debug.  How
does mm usually bring down bearers after a failed dial attempt, e.g.
does it / can it use DTR and/or serial break, or is this down to the
individual plugin?

(gsmtty1): --> 'AT+CGDCONT=1,"IP","internetm2m.air.com"<CR>'
Couldn't initialize PDP context with our APN: 'Serial command timed out'


Cheers,

Tim.

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