I am using the Sierra Wireless MC7455 Modem with an USB PCIe adapter. Whenever I have bad LTE channel condition, the modem crashes and I receive the error message:
[Thu Jan 25 07:01:03 2018] GobiSerial driver ttyUSB1: usb_serial_generic_write_bulk_callback - nonzero urb status: -71
The device stops working. I am unable to communicate via the serial port with the device (raises more of the above errors). The communication link also stays unresponsive:
ifconfig eth0 claims, that the interface still has a valid IP-addresss, but sending only rasies the number of TX errors.
I am currently using the modem for our IoT Platform. This platform may often have bad channel conditions. Our application may also live with the interface not beeing able to send data for a while… but the error disappers only, when the modem is manually unplugged and reattached - which is not acceptable for us
Can you please help me?
Last status information before crash: (note the SINR of -16 dB!. however, the modem is able to send ping or perform small HTTP requests)
Current Time: 483 Temperature: 27 Reset Counter: 2 Mode: ONLINE System mode: LTE PS state: Attached LTE band: B20 LTE bw: 10 MHz LTE Rx chan: 6300 LTE Tx chan: 24300 LTE CA state: NOT ASSIGNED EMM state: Registered Normal Service RRC state: RRC Idle IMS reg state: No Srv PCC RxM RSSI: -61 RSRP (dBm): -105 PCC RxD RSSI: -98 RSRP (dBm): -140 Tx Power: 0 TAC: B043 (45123) RSRQ (dB): -20.0 Cell ID: 00D9AA02 (14264834) SINR (dB): -16.6
- OS: Linux with 4.9.61 Kernel
- Hardware: Cortex A15 (armv7 architecture).
- PCIe to USB Adapter
- LTE Modem: Sierra Wireless MC7455
- Firmware: SWI9X30C_02.24.05.06 r7040 CARMD-EV-FRMWR2 2017/05/19 06:23:09
- Drivers: Gobi Drivers (S2.30N2.48)
- Network Operator: Vodafone Germany
ati Manufacturer: Sierra Wireless, Incorporated Model: MC7455 Revision: SWI9X30C_02.24.05.06 r7040 CARMD-EV-FRMWR2 2017/05/19 06:23:09 MEID: 35907206082974 IMEI: 359072060829740 IMEI SV: 12 FSN: LQ716600190410 +GCAP: +CGSM
Network Operator: Vodafone Germany
at+cgdcont? +CGDCONT: 1,"IP","web.vodafone.de","0.0.0.0",0,0,0,0 at+cops? +cops: 0,0,"Vodafone.de mobilcom-debitel",7