Code:

DLL version:   0.1.12.1
Driver version:   0.1.10.2

bus/device  idVendor/idProduct
bus-0/\\.\libusb0-0001--0x16ad-0x05dc     16AD/05DC
- Manufacturer : obdev.at
- Product      : Akcelerometr_XYZ
  wTotalLength:         32
  bNumInterfaces:       1
  bConfigurationValue:  1
  iConfiguration:       0
  bmAttributes:         80h
  MaxPower:             50
    bInterfaceNumber:   0
    bAlternateSetting:  0
    bNumEndpoints:      2
    bInterfaceClass:    0
    bInterfaceSubClass: 0
    bInterfaceProtocol: 0
    iInterface:         0
      bEndpointAddress: 81h
      bmAttributes:     03h
      wMaxPacketSize:   8
      bInterval:        10
      bRefresh:         0
      bSynchAddress:    0
      bEndpointAddress: 83h
      bmAttributes:     03h
      wMaxPacketSize:   8
      bInterval:        10
      bRefresh:         0
      bSynchAddress:    0

Code:

int main()
{
   usb_dev_handle* hDevice;        
   char buffer[8];

// OpenUsbDevice() - function finding devices and returning hadnle to ones - works fine
   if( (hDevice = OpenUsbDevice()) == 0 ) {
      cout << "Urzadzenie nieodnalezione" << endl; 
      exit(1);
   }
   
   int ctrl = usb_control_msg(hDevice, USB_TYPE_VENDOR, 1, 0, 0, 0, 0, 3000);              // WORKS FINE
   
   if(ctrl < 0 ){
      cout << "Blad polaczenia" << endl;      
      exit(1);
   }
   
   usb_set_configuration(hDevice, 1);
   usb_claim_interface(hDevice, 0);
   cout << usb_strerror() << endl;

   usb_bulk_write(hDevice, USB_ENDPOINT_IN | 1, buffer, sizeof(buffer), 5000);
      
   cout << usb_strerror() << endl;

   usb_release_interface(hDevice, 0);
   usb_close(hDevice);
   system("PAUSE");
   return 0;
}