QConnectManager Timeout issue when used with EC200U

IoT Modules LTE Standard Module
1

Hi All,

We’re using Quectel_QConnectManager_Linux_V1.6.3.2 to establish usb0 network interface with EC200U. The connection is established and internet is working

Auto find qmichannel = /dev/ttyUSB1
Auto find usbnet_adapter = usb0
netcard driver = cdc_ether, driver version = 5.15.32-v8+
Modem works in ECM_RNDIS_NCM mode

But after some time usb0 is gone. From logs we found that AT commands to ttyUSB1 gets timed out. quectel-CM runs ifconfig usb0 down.
But if I manually run sudo ifconfig usb0 up, it works again.
Also, AT command works from ttyUSB6. Only ttyUSB1 not responding.

Log from quectel-CM

AT> AT+CGACT?
onTimeout

or

AT> ATE0Q0V1
handshake fail, TODO …

Please let us know how to solve this issue.

Thanks and Best regards,
Prakash

2

If you run quectel-CM, it will open the AT port. If you ever try to open the AT port again, the quectel-CM would quit.
So there might be some process open the ttyUSB in the background.

3

Hi Bean,

Thanks for the response.
We made sure we don’t use any ttyUSB from our app.
Please let us know if it is possible check whether any other process is using ttyUSB.

Thanks,
Prakash

4

Hi Bean,

Following are the ttyUSB ports in the system:
/dev/ttyUSB0 /dev/ttyUSB1 /dev/ttyUSB2 /dev/ttyUSB3 /dev/ttyUSB4 /dev/ttyUSB5 /dev/ttyUSB6

I stopped quectel-CM and was entering sequence of AT commands manually from minicom using ttyUSB0. After some time (5 mins approx) there was no response in ttyUSB0. Still I can see ttyUSB0 in /dev folder. I’m sure it is not used by any other process. Please let me know if there is anything I can check to find the cause.

Thanks,
Prakash

5

It seems there some urb errors occured.
If you restarts the modem, it will turn OK, is it?

Please use
lsof | grep ttyUSB
to check whether there exists any other proccess occupy the ttyUSB.

If there is no any other process, you can try that:

  1. enumerate the USB again by
    echo 1-1 > /sys/bus/usb/drivers/usb/unbind
    echo 1-1 > /sys/bus/usb/drivers/usb/bind

If it still not work, enumerate the hub
echo 0 > /sys/bus/usb/drivers/usb/usb1/authorized
echo 1 > /sys/bus/usb/drivers/usb/usb1/authorized

If it still not work, please try catch the usbmon log for Quectel.
But I maybe not able to solve it.
It mostly be caused by some hardware issuse. especially caused by the usb hub and the usb cable.

6

Hi Bean,

Yes, if we restart the modem, it will work again.
We connected EC200U evaluation board, it worked fine without any issues.
As you said, there might be some hardware issue in our custom board. We are checking it.
Thanks a lot for your valuable inputs.

Thanks,
Prakash

7

Hi Prakash,
I am facing the exactly same issue. How do you restart the modem? Have you find another issue on your board? Thanks!

Best,
Wenyu

8

Hi Wenyu,

To reset the modem, you can send AT+CFUN=0, wait for 1 sec and send AT+CFUN=1,1
You should not use the serial port used by quecelCM.
We also had some issues with usb connector. We have directly soldered the cable based upon suggestion from our FAE.
Hope it helps you.

Thanks,
Prakash

9

Thank you very much!

Wenyu