Novatel Ovation MC950D Fails/Hungs Intermittently

[nhoeller]

I have successfully connected a Novatel MC950D 3G modem to a PC running Unbuntu 8.10 server using a udev rule to release the ZeroCD and a simple wvdial script. I am using the options.ko driver and getting reasonable speeds (800kbps down, 200kbps up).

Intermittently (4 times today), the modem stops working. Symptoms:

• pppd reports modem has hung up (code=16)
• both /dev/ttyUSB0 and /dev/ttyUSB1 disconnect
• 3B modem reconnects to USB port as usb-storage
• udev rule is involved
• option driver detects GSM modem and connects as ttyUSB0&1 or sometimes ttyUSB1&2
• wvdial is not able to communicate with the modem
• modem LED flashing rapidly in sort of a pinkish color (not listed in the manual or troubleshooting guide)

I need to unplug/replug the modem and restart wvdial to get the modem working again. My local provider has no clue (not trained on Linux).

Any ideas what is going on and what I might do to resolve this problem?

Is there a way using software to simulate unplugging/replugging the modem so I can automate recovery?

Thanks, Norbert

[Sylslay]

Mayby it is heatup?
I use bowl from kitchen table as signal amplifier and noise canceling and working great with Huawei 3g modem. Just ordinary BOWL!!!! === internet 3 times faster.

[Sylslay]

Once I tape few ordinary sawing nidles, under my modem and it start behavor very wrong, seems like yours, flashing, disconnectiq with wvdial.So I took off nidles. So I only put it to bowl and test upload and dowlaoad speed.

[GeorgeVita]

Hi nhoeller,
can you check the modem with other PC and/or Operating System?

The disconnect reason could be hardware, software or caused by the provider. Many times you could have 5 bars signal but no mobile internet (stuck) because your provider cannot serve you.

In your case it seems to be a hardware reason because you are missing /dev/ttyUSBx for a while the led is flashing in a weird style and when you remove it and plug it again it works again. Also the problem appears randomly.

Take a look at my thread: http://forum.huawei.com/jive4/thread...hreadID=323666

Hi Sylslay, I thing it would be better to use an extention cable (just cables without circuit) as described in the above link.

Regards,
George

[nhoeller]

George, interesting! I am using a tri-tip USB cable to increase power to the modem and an extension cable so that I can position the modem near a window. I tested without the extension cable and with only one of the USB connections of the tri-tip plugged in, but have not tried with the 3G modem plugged directly into the PC.

I will wire up your 2nd 'patch' and see if that helps. I may also build another PC to try and eliminate hardware issues with the USB port. I would get the 3G modem replaced but am having difficulty convincing tech support that it might be a modem problem. Intermittent issues are always fun...
Thanks, Norbert

[nhoeller]

George, I wired up your 2nd USB cable patch. The good news is that the modem worked when I plugged it in. The bad news is that the modem hung again last night. I double-checked the wiring and the pin connections (the wires on my cable had different colors from your diagram) and am satisfied that the USB cable patch is correct.

Strangely, I am not seeing this problem when the modem is connected to my Vista laptop. Maybe I was just lucky.

I will build another software router with Windows XP and Linux. That should help me narrow down whether the problem is hardware or software.
Thanks, Norbert

[nhoeller]

I just had the modem fail again. Normally, the modem connects to the cell network over HSUPA. When I unplugged/replugged the modem, the lights suggested it was connecting via EDGE. A second attempt connected via HSDPA. Is it possible that the modem needs to communicate with the driver when switching between cell platforms, and the Linux 'option' driver is not responding properly?

It could also be an issue with my wvdial script. I am using:

[Dialer Defaults]
Modem = /dev/ttyUSB0
Baud = 912600
Init1 = ATZ
Init2 = AT&FE0V1X1&D2&C1S0=0
Stupid Mode = on
Modem Type = USB Modem
Phone = *99#
ISDN = 0

[GeorgeVita]

...
I would get the 3G modem replaced but am having difficulty convincing tech support that it might be a modem problem...

Because everything is "compatible" and "they know better"!

...
Strangely, I am not seeing this problem when the modem is connected to my Vista laptop...

You have to cross check by booting a Live CD (Ubuntu 8.10 ?) to the Vista laptop and use Network Manager to connect. This test will show you if it is a h/w reason.

About HSPA and EDGE switching, many users note that they have some problems, I believe this is more Provider oriented that an O.S. problem. There are some AT commands asking from the modem to use only 3G/HSPA but there is no documentation published except some posts to various forums.

I think that you must find a steady condition laptop/modem/good 3G signal and test the modem for the randomly disconnects which may be caused by a h/w (power) reason. This is the only you can solve with the cable patch.

About your /etc/wvdial.conf: most users use "analog modem" instead of "USB modem" and some providers need the APN definition:
Init3 =AT+CGDCONT=1,"IP","internet"
(in place of "internet" you have to place the proper APN for your provider)

After plugging the modem again, wait for the 3G modem state (usually the blue light) and then try to connect.

If you have any system message when disconnected (wvdial, dmesg) post it here. Have you tried to use Network Manager 0.7?

Regards,
George

[nhoeller]

George, in reverse order, I saw the same problem when I tested the modem on Ubuntu 8.10 desktop with Network Manager 0.7. X-Windows is deadly slow on the PC I am using, so I did not install Gnome or KDE when I rebuilt the system with Ubuntu 8.10 server. The APN information is already 'known' by the modem (verified through minicom).

My Vista system is my work laptop - too much on my plate right now to dedicated it to a potentially long-running Live CD test

Below are the syslog entries around the latest problem. The modem detaches and immediately reattaches. My udev rule disconnects the ZeroCD so that the option driver can grab the device. Most of the time it appears as ttyUSB0/1, but I have seen it show up as ttyUSB1/2.

Mar 29 13:02:59 300PL kernel: [142120.140359] usb 1-2.4: USB disconnect, address 23
Mar 29 13:02:59 300PL kernel: [142120.143494] option 1-2.4:1.0: device disconnected
Mar 29 13:02:59 300PL kernel: [142120.145360] option1 ttyUSB1: GSM modem (1-port) converter now disconnected from ttyUSB1
Mar 29 13:02:59 300PL kernel: [142120.155013] option 1-2.4:1.1: device disconnected
Mar 29 13:02:59 300PL pppd[15345]: Modem hangup
Mar 29 13:02:59 300PL pppd[15345]: Connect time 307.2 minutes.
Mar 29 13:02:59 300PL pppd[15345]: Sent 2831521 bytes, received 16614180 bytes.
Mar 29 13:02:59 300PL pppd[15345]: Connection terminated.
Mar 29 13:02:59 300PL pppd[15345]: Exit.
Mar 29 13:02:59 300PL kernel: [142120.561284] usb 1-2.4: new full speed USB device using uhci_hcd and address 24
Mar 29 13:02:59 300PL kernel: [142120.601593] option1 ttyUSB0: GSM modem (1-port) converter now disconnected from ttyUSB0
Mar 29 13:02:59 300PL kernel: [142120.691916] usb 1-2.4: configuration #1 chosen from 1 choice
Mar 29 13:02:59 300PL kernel: [142120.693550] option 1-2.4:1.0: GSM modem (1-port) converter detected
Mar 29 13:02:59 300PL kernel: [142120.694367] usb 1-2.4: GSM modem (1-port) converter now attached to ttyUSB0
Mar 29 13:02:59 300PL kernel: [142120.698727] option 1-2.4:1.1: GSM modem (1-port) converter detected
Mar 29 13:02:59 300PL kernel: [142120.699425] usb 1-2.4: GSM modem (1-port) converter now attached to ttyUSB1

From previous failures, wvdial/pppd report that the connection to the modem was lost (error = 16, I recall). If I try to start wvdial with the modem in the 'madly blinking' state, it cannot communicate with the device.

I am going to try to find someone at Novatel on Monday who can talk intelligently about their device.
Thanks, Norbert

[nhoeller]

George, I corrected the 'Modem Type' and also removed the Init2 string. I was just going to say that the modem had stayed up the longest time ever (1111 minutes) when it failed. Syslog shows same sequence as above. wvdial log shows:

--> Disconnecting at Mon Mar 30 11:35:11 2009
--> The PPP daemon has died: A modem hung up the phone (exit code = 16)
--> man pppd explains pppd error codes in more detail.
--> Try again and look into /var/log/messages and the wvdial and pppd man pages for more information.
--> Auto Reconnect will be attempted in 5 seconds
--> Cannot open /dev/ttyUSB0: No such file or directory
--> Cannot open /dev/ttyUSB0: No such file or directory
--> Cannot open /dev/ttyUSB0: No such file or directory
--> Disconnecting at Mon Mar 30 11:35:11 2009

pppd error 16 is "The link was terminated by the modem hanging up".

If I run wvdial while the modem is in its 'madly blinking' state, I get back

--> Cannot open /dev/ttuUSB0evice or resource busy.

I tried running minicom against the port - it hung 'Initializing Modem'. Killing minicom caused it to hang 'Resetting Modem'. Rebooting Ubuntu did not help because power to the USB port never dropped.

In parallel with continuing to diagnosing the problem, I have an idea about how to automate resetting the modem. I have an Arduino controller that can listen on the PC serial port and in turn control a 'normally closed' relay wired into the power line of the USB cable. From your understanding of USB cables, is that all I need to do, or do I need to open/close all four leads?
Thanks, Norbert