public void GetZebraUsbDirectPrinters(DiscoveryHandler discoveryHandler)
 {
     try {
         foreach (DiscoveredUsbPrinter printer in UsbDiscoverer.GetZebraUsbPrinters())
         {
             discoveryHandler.FoundPrinter(printer);
         }
         discoveryHandler.DiscoveryFinished();
     } catch (Exception e) {
         discoveryHandler.DiscoveryError(e.Message);
     }
 }