I want to know that if USBCDC with three or more interfaces is supported by using usbser.sys. I can see three VirtualCOM in PC, but one of them shows "not used" in Windows Device Manager. So I can't open it with COM Port program, but the other two VirtualCOM ports work well.
Somebody knows why ? Thank you !!
Any numbers of CDCs are realized on a composite device. I have once done quick (and dirty) test of a composite device of five CDCs for fun :-)
a) Descriptors For CDC descriptors, the interface numbers are referred many times. Check the interface numbers on the interfaces.
Interface number for communication interface - IAD - Interface desc - Union Functional desc
Interface number for data interface - Call management desc - Union Functional desc - Interface desc
b) INF file Did you add the device IDs for each interface to the INF file? like
USB\VID_vvvv&PID_pppp&MI_00, USB\VID_vvvv&PID_pppp&MI_02, USB\VID_vvvv&PID_pppp&MI_04
A single INF can support all interfaces
c) Observe the enumeration just after plug in, using a sniffer. If you don't have a hardware bus analyzer, download this trial and 'evaluate' it. I hope your trouble will be solved by its "rich features" even on the evaluation :-)
SourceUSB http://www.sourcequest.com/
Does the three interfaces give the same enumeration sequence? Any difference on the failed one?
Tsuneo