diff --git a/src/main/java/de/ctdo/bunti/dmx/DMXChannel.java b/src/main/java/de/ctdo/bunti/dmx/DMXChannel.java
index 3a59b8f..528cc76 100644
--- a/src/main/java/de/ctdo/bunti/dmx/DMXChannel.java
+++ b/src/main/java/de/ctdo/bunti/dmx/DMXChannel.java
@@ -4,8 +4,7 @@ public class DMXChannel {
 	private int offset;
 	private String name;
 	private int value;
-	private long lastChangedTimestamp = 0;
-	
+
 	public DMXChannel(int offset, String name) {
 		this.name = name;
 		this.offset = offset;
@@ -18,11 +17,6 @@ public class DMXChannel {
 
 	public final void setValue(int value) {
 		this.value = value;
-		lastChangedTimestamp = System.currentTimeMillis();
-	}
-
-	public final long getLastChangedTimestamp() {
-		return lastChangedTimestamp;
 	}
 
 	public final int getOffset() {
@@ -41,10 +35,6 @@ public class DMXChannel {
 		this.name = name;
 	}
 
-	public final void hasbeenSendOut() {
-		this.lastChangedTimestamp = System.currentTimeMillis();
-	}
-	
 	@Override
 	public final String toString() {
 		return "DMXChannel " + getName() + "," + getOffset() + "," + getValue();
diff --git a/src/main/java/de/ctdo/bunti/dmx/DMXChannels.java b/src/main/java/de/ctdo/bunti/dmx/DMXChannels.java
index c6e83ac..43374f8 100644
--- a/src/main/java/de/ctdo/bunti/dmx/DMXChannels.java
+++ b/src/main/java/de/ctdo/bunti/dmx/DMXChannels.java
@@ -11,8 +11,6 @@ import java.util.Map;
  *
  */
 public class DMXChannels {
-
-	private Map<Integer,DMXChannel> channelByNumber = new HashMap<Integer, DMXChannel>();
 	private Map<String,DMXChannel> channelByName = new HashMap<String, DMXChannel>();
 
 	/**
@@ -20,7 +18,7 @@ public class DMXChannels {
 	 * @return	number of channels
 	 */
 	public final int getCount() {
-		return this.channelByNumber.size();
+		return this.channelByName.size();
 	}
 
 	/**
@@ -35,15 +33,6 @@ public class DMXChannels {
 		return this.channelByName.get(name);
 	}
 
-	/**
-	 * Returns a channel by offset
-	 * @param   number	number
-	 * @return	channel or null if not found
-	 */
-	public final DMXChannel getChannelByNumber(int number) {
-		return this.channelByNumber.get(number);
-	}
-
 	/**
 	 * Adds a channel
 	 * @param channel	channel to add
@@ -58,55 +47,21 @@ public class DMXChannels {
 		if (channel.getName() == null) {
 			return false;
 		}
-		// entry must not exist by offset
-		if (this.channelByNumber.containsKey(channel.getOffset())) {
-			return false;
-		}
 		// entry must not exist by name
 		if (this.channelByName.containsKey(channel.getName())) {
 			return false;
 		}
-		this.channelByNumber.put(channel.getOffset(), channel);
 		this.channelByName.put(channel.getName(), channel);
 		return true;
 	}
 
-	/**
-	 * Removes a channel by offset
-	 * @param offset	offset
-	 * @return	removed channel or null if it does not exist
-	 */
-	public final DMXChannel removeChannel(int offset) {
-		DMXChannel tmpChannel = this.channelByNumber.remove(offset);
-		if (tmpChannel != null) {
-			this.channelByName.remove(tmpChannel.getName());
-		}
-		return tmpChannel;
-	}
 
-	/**
-	 * Removes a channel by name
-	 * @param name	channel name
-	 * @return	removed channel or null if it does not exist
-	 */
-	public final DMXChannel removeChannel(String name) {
-		if (name == null) {
-			return null;
-		}
-		DMXChannel tmpChannel = this.channelByName.remove(name);
-		if (tmpChannel != null) {
-			this.channelByNumber.remove(tmpChannel.getOffset());
-		}
-		return tmpChannel;
-	}
-
-	
 	/**
 	 * Returns an (unmodifiable) collection of all channels
 	 * @return	unmodifiable collection of all channels
 	 */
 	public final Collection<DMXChannel> getAllChannels() {
-		return Collections.unmodifiableCollection(this.channelByNumber.values());
+		return Collections.unmodifiableCollection(this.channelByName.values());
 	}
 
 }
diff --git a/src/main/java/de/ctdo/bunti/dmx/DMXMixer.java b/src/main/java/de/ctdo/bunti/dmx/DMXMixer.java
index 1f5ea80..786fdc6 100644
--- a/src/main/java/de/ctdo/bunti/dmx/DMXMixer.java
+++ b/src/main/java/de/ctdo/bunti/dmx/DMXMixer.java
@@ -6,7 +6,7 @@ import de.ctdo.bunti.model.BuntiDevice;
 
 public interface DMXMixer {
 
-	void setDMX512Channel(int channel, int value);
-	void updateDevice(BuntiDevice device, Map<String, Object> options);
+	boolean setDMX512Channel(int channel, int value);
+	boolean updateDevice(BuntiDevice device, Map<String, Object> options);
 
 }
diff --git a/src/main/java/de/ctdo/bunti/dmx/DMXMixerImpl.java b/src/main/java/de/ctdo/bunti/dmx/DMXMixerImpl.java
index 8526a2a..4a83382 100644
--- a/src/main/java/de/ctdo/bunti/dmx/DMXMixerImpl.java
+++ b/src/main/java/de/ctdo/bunti/dmx/DMXMixerImpl.java
@@ -41,7 +41,7 @@ public class DMXMixerImpl implements DMXMixer, ApplicationListener<DeviceChanged
     }
 
 
-    @Scheduled(fixedDelay = 100) //TODO aendern auf 10ms
+    @Scheduled(fixedDelay = 100)
     public final void sendOutDMXBuffer() {
         if (dmxMap.size() == 0) {
             initDMXData();
@@ -51,11 +51,9 @@ public class DMXMixerImpl implements DMXMixer, ApplicationListener<DeviceChanged
             artNetSender.sendDMXData(dmxMap, artNetDeviceAddress);
             hasDataChanged = false;
         }
-
-//		logger.debug(sb.toString()); 		
     }
 
-    public final void updateDevice(BuntiDevice device, Map<String, Object> options) {
+    public final boolean updateDevice(BuntiDevice device, Map<String, Object> options) {
         BuntiDMXDevice dmxDev = (BuntiDMXDevice) device;
 
         if (dmxDev.setValuesFromOptions(options)) {
@@ -63,21 +61,22 @@ public class DMXMixerImpl implements DMXMixer, ApplicationListener<DeviceChanged
             dmxMap.putAll(dmxDev.getChannelData());
 
             LOGGER.info("setValuesFromOptions on " + device);
-        }
-        else {
-            LOGGER.info("setValuesFromOptions on " + device + " failed");
+            return true;
         }
 
+        LOGGER.info("setValuesFromOptions on " + device + " failed");
+        return false;
     }
 
     @Override
-    public final void setDMX512Channel(int channel, int value) {
+    public final boolean setDMX512Channel(int channel, int value) {
         if (!DMX.checkChannelBoundaries(channel)) {
-            return;
+            return false;
         }
 
         dmxMap.put(channel, DMX.sanitizeDMXValue(value));
         hasDataChanged = true;
+        return true;
     }
 
     @Override
diff --git a/src/test/java/de/ctdo/bunti/model/Strobe1500Test.java b/src/test/java/de/ctdo/bunti/model/Strobe1500Test.java
index 08ad06a..91f2264 100644
--- a/src/test/java/de/ctdo/bunti/model/Strobe1500Test.java
+++ b/src/test/java/de/ctdo/bunti/model/Strobe1500Test.java
@@ -3,8 +3,7 @@ package de.ctdo.bunti.model;
 import org.junit.Before;
 import org.junit.Test;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
+import static junit.framework.Assert.*;
 
 public class Strobe1500Test {
     Strobe1500 dut;