Novatel Ovation MC950D Fails/Hungs Intermittently

**nhoeller** · May 14th, 2009

Rado, adding the -hupcl option on the stty command for the the Arduino port worked like a charm. I can now use echo to communicate with the Arduino.

Code:

stty -F /dev/ttyUSB3 cs8 9600 ignbrk -brkint -icrnl -imaxbel -opost -onlcr -isig -icanon -iexten -echo -echoe -echok -echoctl -echoke noflsh -ixon -crtscts

Thanks, Norbert

**radolin** · May 14th, 2009

I'm glad I helped.

Since you seem OK with it I am not so worried about buying the 626 now

.

My only previous experience with mobile broadband was through a Nokia GSM phone hooked up via bluetooth to the PC, and I got the same disconnects, even on average every 10 minutes. I felt like I have traveled back in time, when I was using a noisy analog phone line and a 14.4 modem

. I talked numerous times with the mobile operator support but they weren't of any help. So it might after all be a carrier issue and not one with the modem.

Greetings,
Rado

**nhoeller** · June 11th, 2009

George, you mentioned in http://ubuntuforums.org/showpost.php...4&postcount=15 that you were able to use minicome to talk to the other ports presented by the 3G modem. In my case, the MF636 connects on dev/ttyUSB0, 1 and 2. wvdial is using dev/ttyUSB2. If I connect via minicom to other of the other ports, it appears the modem hangs (or rather my connection to the Internet fails).

I tried removing all the initialization, reset and dial strings from the minicom profile. If I start minicom, it displays the 'Press CTRL-A Z' message and hangs.

I have had some bandwidth/reliability issues recently that I think were related to my carrier switching from HSUPA to EDGE and GPRS. I was hoping to confirm this on Linux without have to plug the modem into a Windows box.
Thanks, Norbert

**GeorgeVita** · June 12th, 2009

Hi Norbert,

last days I "messed up" all my Ubuntu systems... (I have only various 9.04)!

Before writing a post I always try to TEST everything by myself. When I wrote it I am sure it worked. As I remember it was on 8.04 installation and from terminal "minicom -s". You are right, must remove all init lines, select the same Baud rate to wvdial and minicom (115200 is most reliable and standard for tests).

As developers of Ubuntu trying to get the best from 3G modems sometimes they scramble all ports! You can try only in previous versions where the system cannot find the modem at all! At recent 9.04 there are some stucks/resets with this modem. Also wvdial is not included, usbserial is not an external driver, etc.

I have no 8.04 or 8.10 installation at this time. I tested the new idea below:

1. AT+ZCDRUN=8 (from windows) to modem
2. Boot Ubuntu 8.10 LiveCD (you may use installation).
3. Attach MF636 on USB (no SIM PIN lock!)
4. lsusb shows 19d2 : 0031
5. ls /dev/ttyU* shows no port created
6. sudo modprobe usbserial vendor=0x19d2 product=0x0031
7. ls /dev/ttyU* shows /dev/ttyUSB0 /dev/ttyUSB1 /dev/ttyUSB2
8. sudo gedit /etc/wvdial.conf
9. write tested data into gedit, save, exit, ignore any error messages
10. sudo wvdial ... connected
11. GET minicom via Synaptic Package Manager
12. from a 2nd terminal window: minicom -s
13. choose Serial port setup
14. A- ... /dev/ttyUSB1
15. press ESC
16. choose Modem and dialling
17. edit A to become "~^M~AT^M (CR AT CR)
18. delete all contents into B
19. press ESC
20. press ESC

Now you will see some "status" text running.
Try AT+CSQ you will get the signal strength (GSM mode).
Some commands may affect the main /dev/ttyUSB2 port and disconnect.
Try some commands: ATI AT&V

Note that I wrote this post and testing above connected fine!
All this done "on the fly"...running from the 8.10 LiveCD.

Regards,
George

P.S. Also take a look at my post#4 of http://ubuntuforums.org/showthread.php?t=1181615

**nhoeller** · June 12th, 2009

George, I am not having much luck. For some reason, the ZTE MF636 is connecting on /dev/ttyUSB0 through USB3. wvdial is running on /dev/ttyUSB3. I created minicom profiles for ttyUSB2 and ttyUSB1, identical except for the port.

Code:

# Machine-generated file - use "minicom -s" to change parameters.
pu port             /dev/ttyUSB2
pu minit            ~^M~AT^M
pu mreset

I did not change any of the other settings:

Code:

A - Init string ......... ~^M~AT^M   
B - Reset string ........         
C - Dialing prefix #1.... ATDT  
D - Dialing suffix #1.... ^M 
E - Dialing prefix #2.... ATDP   
F - Dialing suffix #2.... ^M  
G - Dialing prefix #3.... ATX1DT   
H - Dialing suffix #3.... ;X4D^M  
I - Connect string ...... CONNECT    
J - No connect strings .. NO CARRIER            BUSY  
                          NO DIALTONE           VOICE  
K - Hang-up string ...... ~~+++~~ATH^M    
L - Dial cancel string .. ^M      
                                                                           
M - Dial time ........... 45      Q - Auto bps detect ..... No  
N - Delay before redial . 2       R - Modem has DCD line .. Yes   
O - Number of tries ..... 10      S - Status line shows ... DTE speed 
P - DTR drop time (0=no). 1       T - Multi-line untag .... No

The usb2 profile connects:

Code:

Welcome to minicom 2.3

OPTIONS: I18n
Compiled on Oct 24 2008, 06:37:44.
Port /dev/ttyUSB2

                 Press CTRL-A Z for help on special keys

It is not hung (CTRL-A Z works), but it will not accept any input or display any response.

The usb1 profile sits at 'Initializing Modem'.

I tried echoing "AT" to /dev/ttyUSB2 and USB1, and using the 'cp /dev/ttyUSBx myUSBx' command to capture the output. The echo command completes on both ports, but I see no response from the modem. Echoing to /dev/ttyUSB0 hangs the echo command. I wonder if I have to set up the USB2 port with the same specs as wvdial is using? I may need to do some USB Snooping under Windows to see how the 'official' software talks to the ZTE modem.

**GeorgeVita** · June 13th, 2009

Hi Norbert,
you are using 8.10 server while I used 8.10 desktop and 8.10 LiveCD. Also as you are trying "a long term" use without rebooting possibly you have "accumulated" adjustments and resulting to a variable starting point.

Find an 8.10 LiveCD and test my previous post step by step to verify and confirm our "compatibility". There is an extreme case to have different version of firmware inside the modem ... but do not try to upgrade anything now!

When connected to minicom (assuming it will not hang) the other channel sends always some "status" reporting the "UMTS" or "HSPA" switch on network! Other command (I don't remember now) can show you amount of data transfered...

Two more tests and one warning:
- Boot with the modem attached, ls /dev/ttyU* shows 0-1-2-3
- Shut Down. Boot without the modem, wait till system fully loads, attach modem: ls /dev/ttyU* shows 0-1-2
Always the highest is usable for data while -1 or -2 is the 2nd usable port. AFTER a "failed try" I would remove/reattach modem, shut down, boot again. Always in the same manner till find the steady condition. It is painful but this is a "lab test".

The Warning now: Upgrading to 9.04 you may loose the ability to connect via your ZTE modem! Developers have changed everything.

Regards,
George

**iponeverything** · November 11th, 2009

I was having this problem with my ZTE MF626. I stumbled onto this solution while trying to solve another problem..

I installed cu and expect via apt-get and then I run following script to fix the issue. I have it run automatically every time I insert the modem. I have now gone 2 days without a lockup. (before I was lucky to make it 3 hours)

Do a "chown uucp /dev/ttyUSB1" first..

# ========= script start

#!/usr/bin/expect --

set Init3 "AT+CPBS=\"SM\""
set Init4 "AT+CPMS=\"SM\",\"SM\",\"\""

spawn cu -l /dev/ttyUSB1
expect "Connected."

sleep 2

send "AT\r"
expect "OK"

send "AT\r"
expect "OK"

send "$Init3\r"
expect "OK"

send "AT\r"
expect "OK"

send "$Init3\r"
expect "OK"

send "AT\r"
expect "OK"

send "$Init4\r"
expect "OK"

send "AT\r"
expect "OK"

send "$Init4\r"
expect "OK"

exit

# ======= script end

**GeorgeVita** · November 11th, 2009

Hi iponeverything,
this command stops the '+ZUSIMR' message sending repeatedly the modem, but I think this is stopped when connected:

Originally Posted by Sergiu Bivol

...
You are right, +ZUSIMR: 2 means that the modem does not know where to store the SMS messages. I found that issuing the commands

Code:

AT+CPBS="SM"\r\n
AT+CPMS="SM","SM",""\r\n

solve this problem until unplugging the modem. However, I cannot test them, since I do not get the +ZUSIMR messages...

If your problem comes back, check if you can adjust any 'inactivity timer' as ATS7=60 S30=0
At any time you can see 'default' configuration using a terminal program (like minicom) and check output of AT&V

Regards,
George

**iponeverything** · November 13th, 2009

Thanks George, that is helpful.

I think that in my case the +ZUSIMR messages where starting anyway and causing things to get mucked somehow. I could fire up minicom on ttyUSB1 and see the +ZUSIMR:2 messages popping up.

Also, about a third of the time after a fresh boot, wvdial would get hung on this messages..

I have put a script in place to monitor connection and if it hangs to try to redial.. Though what I had found was that most of time the ZTE MF626 would get itself into a an un-recoverable state -- the only solution would be completely shut down system so the dongle would lose power and revert to storage mode. (a soft reboot would keep usb devices powered up) And then to power up the system with wol packet from another machine on the network.

Oddly enough, this GSM connection is the most reliable and fast connection for here in Dushanbe. It's not terribly economical, but its not too bad either.. I can easily hit 200k/sec doing package upgrades sometimes. I was very surprised, I knew that a new fiber turned up here last year - but I didn't think that I could get on it..