RM500U-CNV usb ports disabled after setting "usbnet" to MBIM

IoT Modules 5G Module
1

HI,
I wrongly update the usbnet to MBIM using AT+QCFG=“usbnet”,2. the option 2 is not available in 500 series but in 520 series.
Now i cannot send any AT commands through socat - /dev/ttyUSB or mmcli

mmcli error output:
mmcli -m any --command=‘AT+CFUN=1,1’
error: command failed: ‘GDBus.Error:org.freedesktop.ModemManager1.Error.Core.Connected: No AT port available to run command’

mmcli -m:
mmcli -m any

General | path: /org/freedesktop/ModemManager1/Modem/0
| device id: 35599ab9342c6fcffedc633b1cd993037794fa45

Hardware | manufacturer: Quectel
| model: RM500U-CNV
| firmware revision: sprd
| h/w revision: UDX710_modem
| supported: gsm-umts, lte, 5gnr
| current: gsm-umts, lte, 5gnr
| equipment id: 869955060318586

System | device: /sys/devices/platform/soc/3f980000.usb/usb1/1-1/1-1.1/1-1.1.3
| drivers: option, cdc_mbim
| plugin: quectel
| primary port: cdc-wdm0
| ports: cdc-wdm0 (mbim), wwan0 (net)

Status | unlock retries: sim-pin (3)
| state: enabled
| power state: on
| signal quality: 58% (recent)

Modes | supported: allowed: 2g, 3g, 4g, 5g; preferred: none
| current: allowed: 2g, 3g, 4g, 5g; preferred: none

IP | supported: ipv4, ipv6, ipv4v6

3GPP | imei: 869955060318586
| operator id: 00101
| operator name: Amarisoft Network
| registration: idle
| packet service state: detached

SIM | primary sim path: /org/freedesktop/ModemManager1/SIM/0

Please help so that i can send AT commands again

2

Show the result of cat /sys/kernel/debug/usb/devices
Format the output using </> button.

3

@jfrog Thanks for your reply. Here is the output:

root@rpi3-20231109:/home/tsn#  cat /sys/kernel/debug/usb/devices

T:  Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=480  MxCh= 1
B:  Alloc=  0/800 us ( 0%), #Int=  4, #Iso=  0
D:  Ver= 2.00 Cls=09(hub  ) Sub=00 Prot=01 MxPS=64 #Cfgs=  1
P:  Vendor=1d6b ProdID=0002 Rev= 6.01
S:  Manufacturer=Linux 6.1.0-17-arm64 dwc2_hsotg
S:  Product=DWC OTG Controller
S:  SerialNumber=3f980000.usb
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=  0mA
I:* If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
E:  Ad=81(I) Atr=03(Int.) MxPS=   4 Ivl=256ms

T:  Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  2 Spd=480  MxCh= 4
D:  Ver= 2.00 Cls=09(hub  ) Sub=00 Prot=02 MxPS=64 #Cfgs=  1
P:  Vendor=0424 ProdID=2514 Rev= b.b3
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=  2mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=01 Driver=hub
E:  Ad=81(I) Atr=03(Int.) MxPS=   1 Ivl=256ms
I:* If#= 0 Alt= 1 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=02 Driver=hub
E:  Ad=81(I) Atr=03(Int.) MxPS=   1 Ivl=256ms

T:  Bus=01 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#=  3 Spd=480  MxCh= 3
D:  Ver= 2.00 Cls=09(hub  ) Sub=00 Prot=02 MxPS=64 #Cfgs=  1
P:  Vendor=0424 ProdID=2514 Rev= b.b3
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=  2mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=01 Driver=hub
E:  Ad=81(I) Atr=03(Int.) MxPS=   1 Ivl=256ms
I:* If#= 0 Alt= 1 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=02 Driver=hub
E:  Ad=81(I) Atr=03(Int.) MxPS=   1 Ivl=256ms

T:  Bus=01 Lev=03 Prnt=03 Port=00 Cnt=01 Dev#=  5 Spd=480  MxCh= 0
D:  Ver= 2.10 Cls=ff(vend.) Sub=00 Prot=ff MxPS=64 #Cfgs=  1
P:  Vendor=0424 ProdID=7800 Rev= 3.00
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=  2mA
I:* If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=ff Driver=lan78xx
E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=83(I) Atr=03(Int.) MxPS=  16 Ivl=1ms

T:  Bus=01 Lev=03 Prnt=03 Port=02 Cnt=02 Dev#=  4 Spd=480  MxCh= 0
D:  Ver= 2.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=2c7c ProdID=0900 Rev= 4.04
S:  Manufacturer=Quectel
S:  Product=RM500U-CNV
S:  SerialNumber=0123456789ABCDEF
C:* #Ifs= 6 Cfg#= 1 Atr=c0 MxPwr=500mA
A:  FirstIf#= 0 IfCount= 2 Cls=02(comm.) Sub=0e Prot=00
I:* If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=0e Prot=00 Driver=cdc_mbim
E:  Ad=82(I) Atr=03(Int.) MxPS=  64 Ivl=32ms
I:  If#= 1 Alt= 0 #EPs= 0 Cls=0a(data ) Sub=00 Prot=02 Driver=cdc_mbim
I:* If#= 1 Alt= 1 #EPs= 2 Cls=0a(data ) Sub=00 Prot=02 Driver=cdc_mbim
E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 2 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=option
E:  Ad=83(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 3 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=option
E:  Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 4 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=option
E:  Ad=85(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:* If#= 5 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=00 Prot=00 Driver=option
E:  Ad=86(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
4

You have four serial ports that should be visible as /dev/ttyUSBx.
Stop MM and use any terminal app to access the AT command port, then switch the mode.
The AT port is If#= 4, so you should use /dev/ttyUSB2.

5

@jfrog Thanks for your reply.
i can see the usb ports but cannot access them using minicom or socat.

root@rpi3-20231109:/home/tsn# ls /dev/ttyUSB*
/dev/ttyUSB0  /dev/ttyUSB1  /dev/ttyUSB2  /dev/ttyUSB3  /dev/ttyUSB4

i cannot enter any command in minicom and socat does not respond

root@rpi3-20231109:/home/tsn# socat - /dev/ttyUSB2,crnl
AT

Please help

6

Make sure MM is stopped/disabled and try picocom /dev/ttyUSB2
It looks to me that the output you provided earlier is incomplete and you have another interface with “Driver=option”, so there are five of them in total.