Reset modem while using pppd

["Léo Serre" <leo@lstronic.com>]

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Hello world,

I'm using pppd with a SARA-U201 3G+ modem (from u-blox).
It works fine normally, except in that case:

  1. pppd is connected to the modem correctly
  2. pppd is stopped using poff
  3. The chat script is changed by the user
  4. pppd is started using pon

That introduces an error, since the modem won't accept a new PIN code as 
it is already connected correctly.

The way to fix that is to send a SW reset AT command 'AT+CFUN=1,1' 
between steps 2 and 4.
That's why I introduced a new disconnect chat script which consists of:

     ABORT 'BUSY'
     ABORT 'NO CARRIER'
     ABORT 'VOICE'
     ABORT 'NO DIALTONE'
     ABORT 'NO DIAL TONE'
     ABORT 'NO ANSWER'
     ABORT 'DELAYED'
     TIMEOUT 180
     'OK' 'AT+CFUN=1,1'

I have the following output:

Jan  1 02:24:47 domeradio local2.info chat[568]: abort on (BUSY)
Jan  1 02:24:47 domeradio local2.info chat[568]: abort on (NO CARRIER)
Jan  1 02:24:47 domeradio local2.info chat[568]: abort on (VOICE)
Jan  1 02:24:47 domeradio local2.info chat[568]: abort on (NO DIALTONE)
Jan  1 02:24:47 domeradio local2.info chat[568]: abort on (NO DIAL TONE)
Jan  1 02:24:47 domeradio local2.info chat[568]: abort on (NO ANSWER)
Jan  1 02:24:47 domeradio local2.info chat[568]: abort on (DELAYED)
Jan  1 02:24:47 domeradio local2.info chat[568]: timeout set to 180 seconds
Jan  1 02:24:47 domeradio local2.info chat[568]: expect (OK)
Jan  1 02:24:49 domeradio local2.err chat[568]: SIGTERM
Jan  1 02:24:49 domeradio daemon.warn pppd[534]: Child process 
/usr/sbin/chat -v -t15 -f /etc/ppp/chatscripts/mobile-modem-off.chat 
(pid 567) terminated with signal 15
Jan  1 02:24:49 domeradio daemon.warn pppd[534]: disconnect script failed
Jan  1 02:24:50 domeradio daemon.info pppd[534]: Exit.

It seems that the command is never sent.

My two questions are:

  1. Do you have an idea about the command that is never sent?
  2. Is there an other way to send an AT command while pppd is running 
(or none)?

Thank you,

Léo SERRE
🌍  leo@lstronic.com <mailto:leo@lstronic.com>
📧  lstronic.com <http://lstronic.com>

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