RNDIS configured in USB CDC1 is not working

Hi ,

I am working on a project where both VCOM port and RNDIS needs to be configured on the same USB device.

Method1: I have configured CDC0 as a VCOM port and CDC1 as a RNDIS. In this configuration VCOM port works perfectly fine. But the RNDIS is not working. When I check the device status in the device manager it like below: 

This device cannot start. (Code 10)

{Operation Failed}
The requested operation was unsuccessful.

Method2: I have configured CDC0 as a RNDIS and CDC1 as a VCOM port. In this configuration RNDIS works perfectly fine. But the VCOM port doesn't receives the frame which is grater than 64bytes.

Controller: LPC43S57

Environment: Keil

RTOS: CMSIS RTOS2

  • As confirmed by Keil Engineering, this obviously is a problem related to Windows drivers for such combinations, because the.inf file for the RNDIS is set up for RNDIS using first interfaces - so it will not work if you change the location of RNDIS interfaces on the device.


    Also, CDC is probably mounted by default only if it is the only or first interface on the device
    otherwise .inf file is required to mount it properly.


    So, in this combination, the user will have to construct his .inf file for Windows to
    properly mount and communicate with the device.