diff --git a/java/src/ch/ntb/usb/Device.java b/java/src/ch/ntb/usb/Device.java
index bf2b595..e72f7dd 100644
--- a/java/src/ch/ntb/usb/Device.java
+++ b/java/src/ch/ntb/usb/Device.java
@@ -23,8 +23,18 @@ public class Device {
 
 	private int maxPacketSize;
 
-	private int idVendor, idProduct, dev_configuration, dev_interface,
-			dev_altinterface;
+	/**
+	 * Mandatory identification values for the device.
+	 */
+	private int idVendor, idProduct;
+
+	/**
+	 * Optional identification value for the device (e.g. if there are multiple
+	 * devices with the same vendor and product id).
+	 */
+	private String filename;
+
+	private int dev_configuration, dev_interface, dev_altinterface;
 
 	private long usbDevHandle;
 
@@ -34,32 +44,22 @@ public class Device {
 
 	private Usb_Device dev;
 
-	private boolean initUSBDone;
-
 	protected Device(short idVendor, short idProduct) {
-		initUSBDone = false;
 		resetOnFirstOpen = false;
 		resetDone = false;
 		maxPacketSize = -1;
 		this.idVendor = idVendor;
 		this.idProduct = idProduct;
+		this.filename = null;
 	}
 
-	private void initUSB() {
-		LibusbJava.usb_init();
-		initUSBDone = true;
-	}
-
-	private Usb_Bus initBus() throws USBException {
-		LibusbJava.usb_find_busses();
-		LibusbJava.usb_find_devices();
-
-		Usb_Bus bus = LibusbJava.usb_get_busses();
-		if (bus == null) {
-			throw new USBException("LibusbJava.usb_get_busses(): "
-					+ LibusbJava.usb_strerror());
-		}
-		return bus;
+	protected Device(short idVendor, short idProduct, String filename) {
+		resetOnFirstOpen = false;
+		resetDone = false;
+		maxPacketSize = -1;
+		this.idVendor = idVendor;
+		this.idProduct = idProduct;
+		this.filename = filename;
 	}
 
 	private void updateMaxPacketSize(Usb_Device device) throws USBException {
@@ -84,8 +84,14 @@ public class Device {
 		}
 	}
 
-	private Usb_Device initDevice() throws USBException {
-		Usb_Bus bus = initBus();
+	/**
+	 * Initializes the device. The parameters <code>idVendor</code> and
+	 * <code>idProduct</code> are mandatory. The parameter
+	 * <code>filename</code> is optional.
+	 */
+	private Usb_Device initDevice(int idVendorParam, int idProductParam,
+			String filename) throws USBException {
+		Usb_Bus bus = USB.getBus();
 
 		Usb_Device device = null;
 		// search for device
@@ -93,8 +99,17 @@ public class Device {
 			device = bus.getDevices();
 			while (device != null) {
 				Usb_Device_Descriptor devDesc = device.getDescriptor();
-				if ((devDesc.getIdVendor() == idVendor)
-						&& (devDesc.getIdProduct() == idProduct)) {
+				if (filename != null
+						&& filename.compareTo(device.getFilename()) == 0
+						&& devDesc.getIdVendor() == idVendorParam
+						&& devDesc.getIdProduct() == idProductParam) {
+					// idVendor, idProduct and filename
+					logger.info("Device found: " + device.getFilename());
+					updateMaxPacketSize(device);
+					return device;
+				} else if (devDesc.getIdVendor() == idVendorParam
+						&& devDesc.getIdProduct() == idProductParam) {
+					// only idVendor and idProduct
 					logger.info("Device found: " + device.getFilename());
 					updateMaxPacketSize(device);
 					return device;
@@ -114,9 +129,7 @@ public class Device {
 	 * @throws USBException
 	 */
 	public void updateDescriptors() throws USBException {
-		if (!initUSBDone)
-			initUSB();
-		dev = initDevice();
+		dev = initDevice(idVendor, idProduct, filename);
 	}
 
 	/**
@@ -175,9 +188,7 @@ public class Device {
 			throw new USBException("device opened, close or reset first");
 		}
 
-		initUSB();
-
-		dev = initDevice();
+		dev = initDevice(idVendor, idProduct, filename);
 
 		if (dev != null) {
 			long res = LibusbJava.usb_open(dev);
@@ -724,4 +735,26 @@ public class Device {
 		resetOnFirstOpen = enable;
 		resetTimeout = timeout;
 	}
+
+	/**
+	 * Returns the optional filename which is set when there are multiple
+	 * devices with the same vendor and product id. See
+	 * {@link USB#getDevice(short, short, String)}. Use
+	 * {@link Usb_Device#getFilename()} to read the filename of a device.
+	 * 
+	 * @return the filename if set or null
+	 */
+	protected String getFilename() {
+		return filename;
+	}
+
+	/**
+	 * Returns the Usb_Device instance associated with this device. This value
+	 * is only valid after opening the device.
+	 * 
+	 * @return the Usb_Device instance associated with this device.
+	 */
+	public Usb_Device getDevice() {
+		return dev;
+	}
 }
diff --git a/java/src/ch/ntb/usb/USB.java b/java/src/ch/ntb/usb/USB.java
index f9b293d..6948f9a 100644
--- a/java/src/ch/ntb/usb/USB.java
+++ b/java/src/ch/ntb/usb/USB.java
@@ -167,6 +167,8 @@ public class USB {
 
 	private static LinkedList<Device> devices = new LinkedList<Device>();
 
+	private static boolean initUSBDone = false;
+
 	/**
 	 * Create a new device an register it in a device queue. If the device is
 	 * already registered, a reference to it will be returned.<br>
@@ -175,22 +177,38 @@ public class USB {
 	 *            the vendor id of the USB device
 	 * @param idProduct
 	 *            the product id of the USB device
+	 * @param filename
+	 *            an optional filename which can be used to distinguish multiple
+	 *            devices with the same vendor and product id.
 	 * @return a newly created device or an already registered device
 	 */
-	public static Device getDevice(short idVendor, short idProduct) {
+	public static Device getDevice(short idVendor, short idProduct,
+			String filename) {
 
 		// check if this device is already registered
-		Device dev = getRegisteredDevice(idVendor, idProduct);
+		Device dev = getRegisteredDevice(idVendor, idProduct, filename);
 		if (dev != null) {
 			logger.info("return already registered device");
 			return dev;
 		}
-		dev = new Device(idVendor, idProduct);
+		dev = new Device(idVendor, idProduct, filename);
 		logger.info("create new device");
 		devices.add(dev);
 		return dev;
 	}
 
+	/**
+	 * See {@link #getDevice(short, short, String)}. The parameter
+	 * <code>filename</code> is set to null.
+	 * 
+	 * @param idVendor
+	 * @param idProduct
+	 * @return
+	 */
+	public static Device getDevice(short idVendor, short idProduct) {
+		return getDevice(idVendor, idProduct, null);
+	}
+
 	/**
 	 * Get an already registered device or null if the device does not exist.<br>
 	 * 
@@ -198,16 +216,55 @@ public class USB {
 	 *            the vendor id of the USB device
 	 * @param idProduct
 	 *            the product id of the USB device
+	 * @param filename
+	 *            an optional filename which can be used to distinguish multiple
+	 *            devices with the same vendor and product id.
 	 * @return the device or null
 	 */
-	private static Device getRegisteredDevice(short idVendor, short idProduct) {
+	private static Device getRegisteredDevice(short idVendor, short idProduct,
+			String filename) {
 		for (Iterator<Device> iter = devices.iterator(); iter.hasNext();) {
 			Device dev = iter.next();
-			if ((dev.getIdVendor() == idVendor)
-					&& (dev.getIdProduct() == idProduct)) {
+			if (filename != null && filename.compareTo(dev.getFilename()) == 0
+					&& dev.getIdVendor() == idVendor
+					&& dev.getIdProduct() == idProduct) {
+				return dev;
+			} else if (dev.getIdVendor() == idVendor
+					&& dev.getIdProduct() == idProduct) {
 				return dev;
 			}
 		}
 		return null;
 	}
+
+	/**
+	 * Returns the root {@link Usb_Bus} element.
+	 * 
+	 * @return the root {@link Usb_Bus} element
+	 * @throws USBException
+	 */
+	public static Usb_Bus getBus() throws USBException {
+		if (!initUSBDone) {
+			init();
+		}
+		LibusbJava.usb_find_busses();
+		LibusbJava.usb_find_devices();
+
+		Usb_Bus bus = LibusbJava.usb_get_busses();
+		if (bus == null) {
+			throw new USBException("LibusbJava.usb_get_busses(): "
+					+ LibusbJava.usb_strerror());
+		}
+		return bus;
+	}
+
+	/**
+	 * Explicitly calls {@link LibusbJava#usb_init()}. Note that you don't need
+	 * to call this procedure as it is called implicitly when creating a new
+	 * device with {@link USB#getDevice(short, short, String)}.
+	 */
+	public static void init() {
+		LibusbJava.usb_init();
+		initUSBDone = true;
+	}
 }
diff --git a/java/src/ch/ntb/usb/Utils.java b/java/src/ch/ntb/usb/Utils.java
index fef8fc3..e14591d 100644
--- a/java/src/ch/ntb/usb/Utils.java
+++ b/java/src/ch/ntb/usb/Utils.java
@@ -7,35 +7,43 @@
  */
 package ch.ntb.usb;
 
+import java.io.PrintStream;
+
 public class Utils {
 
 	public static void logBus(Usb_Bus bus) {
+		logBus(bus, System.out);
+	}
+
+	public static void logBus(Usb_Bus bus, PrintStream out) {
 		Usb_Bus usb_Bus = bus;
 		while (usb_Bus != null) {
-			System.out.println(usb_Bus.toString());
+			out.println(usb_Bus.toString());
 			Usb_Device dev = usb_Bus.getDevices();
 			while (dev != null) {
-				System.out.println("\t" + dev.toString());
+				out.println("\t" + dev.toString());
 				// Usb_Device_Descriptor
 				Usb_Device_Descriptor defDesc = dev.getDescriptor();
-				System.out.println("\t\t" + defDesc.toString());
+				out.println("\t\t" + defDesc.toString());
 				// Usb_Config_Descriptor
 				Usb_Config_Descriptor[] confDesc = dev.getConfig();
 				for (int i = 0; i < confDesc.length; i++) {
-					System.out.println("\t\t" + confDesc[i].toString());
+					out.println("\t\t" + confDesc[i].toString());
 					Usb_Interface[] int_ = confDesc[i].getInterface();
 					if (int_ != null) {
 						for (int j = 0; j < int_.length; j++) {
-							System.out.println("\t\t\t" + int_[j].toString());
-							Usb_Interface_Descriptor[] intDesc = int_[j].getAltsetting();
+							out.println("\t\t\t" + int_[j].toString());
+							Usb_Interface_Descriptor[] intDesc = int_[j]
+									.getAltsetting();
 							if (intDesc != null) {
 								for (int k = 0; k < intDesc.length; k++) {
-									System.out.println("\t\t\t\t"
+									out.println("\t\t\t\t"
 											+ intDesc[k].toString());
-									Usb_Endpoint_Descriptor[] epDesc = intDesc[k].getEndpoint();
+									Usb_Endpoint_Descriptor[] epDesc = intDesc[k]
+											.getEndpoint();
 									if (epDesc != null) {
 										for (int e = 0; e < epDesc.length; e++) {
-											System.out.println("\t\t\t\t\t"
+											out.println("\t\t\t\t\t"
 													+ epDesc[e].toString());
 										}
 									}
diff --git a/java/test/ch/ntb/usb/test/DeviceTest.java b/java/test/ch/ntb/usb/test/DeviceTest.java
index 1146a6e..7b43925 100644
--- a/java/test/ch/ntb/usb/test/DeviceTest.java
+++ b/java/test/ch/ntb/usb/test/DeviceTest.java
@@ -8,13 +8,17 @@
 package ch.ntb.usb.test;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
+import java.io.ByteArrayOutputStream;
 import java.io.FileInputStream;
 import java.io.InputStream;
+import java.io.PrintStream;
 import java.io.UnsupportedEncodingException;
 import java.util.Properties;
+import java.util.logging.Logger;
 
 import junit.framework.Assert;
 
@@ -26,8 +30,10 @@ import ch.ntb.usb.Device;
 import ch.ntb.usb.LibusbJava;
 import ch.ntb.usb.USB;
 import ch.ntb.usb.USBException;
+import ch.ntb.usb.Usb_Bus;
 import ch.ntb.usb.Usb_Config_Descriptor;
 import ch.ntb.usb.Usb_Device_Descriptor;
+import ch.ntb.usb.Utils;
 import ch.ntb.usb.testApp.AbstractDeviceInfo;
 import ch.ntb.usb.testApp.AbstractDeviceInfo.TransferMode;
 
@@ -48,6 +54,8 @@ public class DeviceTest {
 
 	private static Device dev;
 
+	private static Logger log = Logger.getLogger(DeviceTest.class.getName());
+
 	@SuppressWarnings("unchecked")
 	@BeforeClass
 	public static void setUp() throws Exception {
@@ -71,6 +79,17 @@ public class DeviceTest {
 		// initialise the device
 		LibusbJava.usb_set_debug(255);
 		dev = USB.getDevice(devinfo.getIdVendor(), devinfo.getIdProduct());
+		assertNotNull(dev);
+
+		// print the devices
+		LibusbJava.usb_init();
+		LibusbJava.usb_find_busses();
+		LibusbJava.usb_find_devices();
+		Usb_Bus bus = LibusbJava.usb_get_busses();
+		ByteArrayOutputStream baos = new ByteArrayOutputStream();
+		PrintStream ps = new PrintStream(baos);
+		Utils.logBus(bus, ps);
+		log.info(baos.toString());
 	}
 
 	@SuppressWarnings("null")
@@ -78,11 +97,11 @@ public class DeviceTest {
 	public void getDescriptors() throws Exception {
 		dev.updateDescriptors();
 		Usb_Device_Descriptor devDescriptor = dev.getDeviceDescriptor();
-		assertTrue(devDescriptor != null);
+		assertNotNull(devDescriptor);
 		assertEquals(devinfo.getIdProduct(), devDescriptor.getIdProduct());
 		assertEquals(devinfo.getIdVendor(), devDescriptor.getIdVendor());
 		Usb_Config_Descriptor confDescriptors[] = dev.getConfigDescriptors();
-		assertTrue(confDescriptors != null);
+		assertNotNull(confDescriptors);
 		assertTrue(confDescriptors[0].getInterface().length > 0);
 	}
 
@@ -139,6 +158,20 @@ public class DeviceTest {
 		doClose();
 	}
 
+	@Test
+	public void openWithFilename() throws Exception {
+		// get device by filename
+		doOpen();
+		assertNotNull(dev.getDevice());
+		String oldFilename = dev.getDevice().getFilename();
+		assertNotNull(oldFilename);
+		log.info("Filename: " + oldFilename);
+		Device dev2 = USB.getDevice(devinfo.getIdVendor(), devinfo
+				.getIdProduct(), oldFilename);
+		assertEquals(dev, dev2);
+		doClose();
+	}
+
 	@Test
 	public void bulkWriteRead() throws Exception {
 		checkBulkEndpoints();
@@ -224,8 +257,8 @@ public class DeviceTest {
 	@Test
 	public void controlMsg() throws Exception {
 		try {
-			dev.open(devinfo.getConfiguration(), devinfo.getInterface(), devinfo
-					.getAltinterface());
+			dev.open(devinfo.getConfiguration(), devinfo.getInterface(),
+					devinfo.getAltinterface());
 			// GET STATUS (device)
 			byte[] data = getTestData(2);
 			int length = dev.controlMsg(USB.REQ_TYPE_DIR_DEVICE_TO_HOST
@@ -237,10 +270,11 @@ public class DeviceTest {
 			assertEquals((byte) 0x00, data[1]);
 			// GET STATUS (interface)
 			data = getTestData(2);
-			length = dev.controlMsg(USB.REQ_TYPE_DIR_DEVICE_TO_HOST
-					| USB.REQ_TYPE_TYPE_STANDARD | USB.REQ_TYPE_RECIP_INTERFACE,
-					USB.REQ_GET_STATUS, 0, 0, data, data.length, devinfo
-							.getTimeout(), false);
+			length = dev.controlMsg(
+					USB.REQ_TYPE_DIR_DEVICE_TO_HOST
+							| USB.REQ_TYPE_TYPE_STANDARD
+							| USB.REQ_TYPE_RECIP_INTERFACE, USB.REQ_GET_STATUS,
+					0, 0, data, data.length, devinfo.getTimeout(), false);
 			assertTrue(length > 0);
 			assertEquals((byte) 0x00, data[0]);
 			assertEquals((byte) 0x00, data[1]);
@@ -265,7 +299,8 @@ public class DeviceTest {
 			// data = byte[1];
 			// length = dev.controlMsg(USB.REQ_TYPE_DIR_DEVICE_TO_HOST
 			// | USB.REQ_TYPE_TYPE_STANDARD | USB.REQ_TYPE_RECIP_INTERFACE,
-			// USB.REQ_GET_INTERFACE, 0, devinfo.getInterface(), data, data.length,
+			// USB.REQ_GET_INTERFACE, 0, devinfo.getInterface(), data,
+			// data.length,
 			// devinfo
 			// .getTimeout(), false);
 			// logData(data, length);
@@ -273,8 +308,8 @@ public class DeviceTest {
 			data = getTestData(128);
 			length = dev.controlMsg(USB.REQ_TYPE_DIR_DEVICE_TO_HOST
 					| USB.REQ_TYPE_TYPE_STANDARD | USB.REQ_TYPE_RECIP_DEVICE,
-					USB.REQ_GET_DESCRIPTOR, 1 << 8, 0, data, data.length, devinfo
-							.getTimeout(), false);
+					USB.REQ_GET_DESCRIPTOR, 1 << 8, 0, data, data.length,
+					devinfo.getTimeout(), false);
 			validateDeviceDescriptor(data, length);
 			// GET DESCRIPTOR (string descriptor (1))
 			data = getTestData(128);
@@ -369,14 +404,15 @@ public class DeviceTest {
 		return b;
 	}
 
+	@SuppressWarnings("unused")
 	private void logData(byte[] data, int length) {
 		if (length > 0) {
-			System.out.println("length: " + length);
+			log.info("length: " + length);
+			String logData = "";
 			for (int i = 0; i < length; i++) {
-				System.out.print("0x" + Integer.toHexString(data[i] & 0xff)
-						+ "\t");
+				logData += "0x" + Integer.toHexString(data[i] & 0xff) + "\t";
 			}
-			System.out.println();
+			log.info(logData);
 		}
 	}
 
@@ -399,8 +435,7 @@ public class DeviceTest {
 					devinfo.getAltinterface());
 			fail("USBException expected");
 		} catch (USBException e) {
-			System.err.println("INFO: " + getClass()
-					+ ": error expected: could not set config "
+			log.severe("could not set config "
 					+ (devinfo.getConfiguration() + 5));
 		}
 		doOpenWriteReadClose();
@@ -413,8 +448,7 @@ public class DeviceTest {
 					devinfo.getAltinterface());
 			fail("USBException expected");
 		} catch (USBException e) {
-			System.err.println("INFO: " + getClass()
-					+ ": error expected: could not claim interface "
+			log.severe("could not claim interface "
 					+ (devinfo.getInterface() + 5));
 		}
 		doOpenWriteReadClose();
@@ -427,8 +461,7 @@ public class DeviceTest {
 					devinfo.getAltinterface() + 5);
 			fail("USBException expected");
 		} catch (USBException e) {
-			System.err.println("INFO: " + getClass()
-					+ ": error expected: could not set alt interface "
+			log.severe("could not set alt interface "
 					+ (devinfo.getAltinterface() + 5));
 		}
 		doOpenWriteReadClose();
@@ -436,33 +469,33 @@ public class DeviceTest {
 
 	@Test
 	public void testGetIdProduct() {
-		Assert.assertEquals(dev.getIdProduct(), devinfo.getIdProduct());
+		Assert.assertEquals(devinfo.getIdProduct(), dev.getIdProduct());
 	}
 
 	@Test
 	public void testGetIdVendor() {
-		Assert.assertEquals(dev.getIdVendor(), devinfo.getIdVendor());
+		Assert.assertEquals(devinfo.getIdVendor(), dev.getIdVendor());
 	}
 
 	@Test
 	public void testGetAltinterface() {
-		Assert.assertEquals(dev.getAltinterface(), devinfo.getAltinterface());
+		Assert.assertEquals(devinfo.getAltinterface(), dev.getAltinterface());
 	}
 
 	@Test
 	public void testGetConfiguration() {
-		Assert.assertEquals(dev.getConfiguration(), devinfo.getConfiguration());
+		Assert.assertEquals(devinfo.getConfiguration(), dev.getConfiguration());
 	}
 
 	@Test
 	public void testGetInterface() {
-		Assert.assertEquals(dev.getInterface(), devinfo.getInterface());
+		Assert.assertEquals(devinfo.getInterface(), dev.getInterface());
 	}
 
 	@Test
 	public void testGetMaxPacketSize() throws USBException {
 		doOpen();
-		Assert.assertEquals(dev.getMaxPacketSize(), devinfo.getMaxDataSize());
+		Assert.assertEquals(devinfo.getMaxDataSize(), dev.getMaxPacketSize());
 		doClose();
 	}
 
@@ -495,7 +528,8 @@ public class DeviceTest {
 				if (devinfo.getOutEPBulk() != -1) {
 					dev.writeBulk(devinfo.getOutEPBulk(), testData,
 							testData.length, devinfo.getTimeout(), false);
-				} else if (devinfo.getInEPBulk() != -1) {
+				}
+				if (devinfo.getInEPBulk() != -1) {
 					dev.readBulk(devinfo.getInEPBulk(), readData,
 							readData.length, devinfo.getTimeout(), false);
 				}
@@ -503,18 +537,22 @@ public class DeviceTest {
 				if (devinfo.getOutEPInt() != -1) {
 					dev.writeInterrupt(devinfo.getOutEPInt(), testData,
 							testData.length, devinfo.getTimeout(), false);
-				} else if (devinfo.getInEPInt() != -1) {
+				}
+				if (devinfo.getInEPInt() != -1) {
 					dev.readInterrupt(devinfo.getInEPInt(), readData,
 							readData.length, devinfo.getTimeout(), false);
 				}
 			}
+			if (devinfo.doCompareData()) {
+				compare(testData, readData);
+			}
+		} catch (AssertionError e) {
+			closeOnException();
+			throw e;
 		} catch (Exception e) {
 			closeOnException();
 			throw e;
 		}
-		if (devinfo.doCompareData()) {
-			compare(testData, readData);
-		}
 	}
 
 	private static void compare(byte[] d1, byte[] d2) {