Customised USB OTG composite - usb serial


I have a project which needs a USB serial port.

I used method → “Customize Endpoints” section

to create a file /etc/legato/usbmode with contents:


This creates

Which is great.

The problem is that when the WP85 OTG is plugged into a windows machine - I get error 10 in device manager.
If the WP85 has a standard USB configuration it works fine with the same windows machine
I’m guessing that the SW driver only works with the standard WP85 configuration?
Any ideas how to get a driver to work with the new WP85 configuration?

Thanks in advance


Hi @johnofleek

Unfortunately, it appears that the Windows driver is only compatible with the compositions you can setup with AT!USBCOMP command.
Other customizations are fine for a Linux host, but not for a Windows one (will ensure that this limitation is mentioned in the documentation).

Hi David

Many thanks for the clarification - it’s a shame that serial isn’t available in the standard composition options.
To aid my memory in the future for the WP85 Legato 16.10.1 the following is the standard response to


- configuration index to which the composition applies, should be 1

- 1:Generic

- DIAG - 0x00000001,
NMEA - 0x00000004,
MODEM - 0x00000008,
AT - 0x00000010,
OSA - 0x00000020,
RAWDATA - 0x00000040,
RMNET0 - 0x00000100,
RMNET1 - 0x00000400,
MBIM - 0x00001000,
RNDIS - 0x00004000,
AUDIO - 0x00010000,
ECM - 0x00080000,
10D - diag, nmea, modem, rmnet interfaces enabled
1009 - diag, modem, mbim interfaces enabled


Config Index: 1
Config Type: 1 (Generic)
Interface bitmask: 0008015D (diag,nmea,modem,at,rawdata,rmnet0,ecm)



Config Index: 1
Config Type: 1 (Generic)
Interface bitmask: 0008015D (diag,nmea,modem,at,rawdata,rmnet0,ecm)