Re:MCP2200 VCP doesn't work
For a workaround of RTS issue of Windows usbser.sys,
Put RTS and then DTR (or both RTS and DTR simultaneously).
RTS signaling is sent at the timing when DTR is put, over single SET_CONTROL_LINE_STATE request.
You don't need to toggle DTR. Any value (0/1) will do, regardless of former DTR status.