Can't communicate to composite CDC device in Darwin

[Jason K. <jas...@gm...>]

Libusb Team - 

I've just made a new device which is a composite device that has 3 interfaces; The two needed for the CDC class, and a vendor specific interface.

I can't open the vendor specific device for communication. I open the device, which the libusb error messages says:

USBDeviceOpen: another process has device opened for exclusive access 

However it continues.

When I try and claim the interface, that works fine. However, shortly after I get the following:

libusb: 0.612045 error [submit_control_transfer] control request failed: no async port has been opened for interface

And that message follows with any successive control transfer I try to do on my claimed interface.

Was wondering if there was a way around this, if this is a limitation on the Mac, or if I've made a mistake in my descriptors?

The idea was to have a vendor specific device we can talk to for all our bulk data transfers, and then conveniently have a serial port we can connect to for debug without using another USB cable and rs232 convertor.

Thanks so much, really appreciate the help.

Very Sincerely,
Jason