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Old 01-28-2012, 10:36 AM   #1
shams
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usb dialup modem problem?


I installed the debian wheezy and use the usb dialup modem to connect the internet, the modem port is "/dev/ttyACM0" and it was woking, but snice few days this problem araised.
During connection the system changing the usb modem id between "/dev/ttyACM0" and "/dev/ttyACM1" without any reason even i ddin't attach any usb device. this is the /var/log/messages:

Quote:
Jan 28 13:30:26 example kernel: [ 6.579461] input: HDA Intel Headphone as /devices/pci0000:00/0000:00:1b.0/sound/card0/input7
Jan 28 13:30:26 example kernel: [ 6.598449] cdc_acm 4-2:1.0: ttyACM0: USB ACM device
Jan 28 13:30:26 example kernel: [ 6.600125] usbcore: registered new interface driver cdc_acm
Jan 28 13:30:26 example kernel: [ 6.600128] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters

Jan 28 13:57:09 example pppd[3020]: Modem hangup
Jan 28 13:57:09 example pppd[3020]: Connect time 23.9 minutes.
Jan 28 13:57:09 example pppd[3020]: Sent 540090 bytes, received 4299636 bytes.
Jan 28 13:57:09 example pppd[3020]: Connection terminated.
Jan 28 13:57:09 example kernel: [ 1615.888052] usb 4-2: USB disconnect, device number 2
Jan 28 13:57:10 example kernel: [ 1616.128017] usb 4-2: new full speed USB device number 3 using uhci_hcd
Jan 28 13:57:10 example kernel: [ 1616.813357] usb 4-2: New USB device found, idVendor=0572, idProduct=1329
Jan 28 13:57:10 example kernel: [ 1616.813362] usb 4-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
Jan 28 13:57:10 example kernel: [ 1616.813365] usb 4-2: Product: USB Modem
Jan 28 13:57:10 example kernel: [ 1616.813368] usb 4-2: Manufacturer: Conexant
Jan 28 13:57:10 example kernel: [ 1616.813370] usb 4-2: SerialNumber: 24680246
Jan 28 13:57:10 example kernel: [ 1616.816419] cdc_acm 4-2:1.0: ttyACM1: USB ACM device
Jan 28 13:57:10 example mtp-probe: checking bus 4, device 3: "/sys/devices/pci0000:00/0000:00:1d.2/usb4/4-2
This is lsusb:

Quote:
Bus 004 Device 003: ID 0572:1329 Conexant Systems (Rockwell), Inc.
 
Old 01-28-2012, 12:10 PM   #2
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Why not make ACM1 a symlink to ACM0 or vice-versa?
 
Old 01-30-2012, 09:08 AM   #3
shams
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thanks for the reply, i open the /dev and didn't find the ttyACM1, there is only ttyACM0, how i can create /dev/ttyACM1 in /dev/ directory to link.
 
Old 01-30-2012, 12:38 PM   #4
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Quote:
cd /dev
sudo ln -s ACM0 ACM1
That should do it.
 
Old 02-09-2012, 11:16 AM   #5
shams
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I run the above command and created the link, but ttyACM1 disappear after reboot, when i disconnect the usb modem cable from the port the /dev/ttyACM0 disappearing as well and after reconnect it come again. so i should make the links after every system boot.
 
Old 02-09-2012, 12:29 PM   #6
colorpurple21859
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look in /etc/udev/rules.d and see if there is a persistent.net or persistent.usb file or something similar that can be edited, it may be pointing to the wrong device.
 
Old 02-09-2012, 08:02 PM   #7
shams
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Thanks for reply, there is no any rules for the usb in the /etc/udev/rules.d.
 
Old 02-10-2012, 02:28 AM   #8
business_kid
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The behaviour you describe is correct.

/dev is mounted on some temporary system, and vanishes every time. Udev makes /dev/acm0 when it existys, and removes it when it doesn't exist. You don't really want your pc to talk to the modem while it's not there, do you? find ACM0 (in /lib/udev/ruled.d or somewhere your distro felt like putting it) and ls -l it, it will have a major and a minor number

<type>perms user group ACM0 x y

where y is the minor number. Add 1 to the minor and you can add ACM1
 
Old 02-11-2012, 10:35 AM   #9
shams
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Thanks for the reply, i check the /lib/udev/rules.d but didn't find any rules for ACM0 or ACM1.

Last edited by shams; 02-11-2012 at 10:37 AM.
 
Old 02-11-2012, 01:26 PM   #10
business_kid
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If you travel to /etc/modprobe.d/ you can set them up with a postinstall command

Alias dodgy_modem somemod
postinstall somemod mknod [options] && mknod [options]
 
  


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