In Eclipse starting up the Android emulator the LogCat does not always detect it. In the console you can read the following error:
Unexpected error while launching logcat. Try reselcting the device.] device not found
com.android.ddmlib.AdbCommandRejectedException: device not found
at com.android.ddmlib.AdHelper.setDevice(AdbHelper.java:752)
at com.android.ddmlib.AdbHelper.executeRemoteCommand(AdHelper.java:373)
at com.android.ddmlib.Device.executeShellCommand(Device.java:397)
at com.android.ddmuilib.logcat.LogCatReceiver$1.run(LogCatReceiver.java:102)
at java.lang.Thread.run(Unknown Source)
To solve this. Go to the DDMS perspective
Menu -> Window -> Open Perspective -> DDMS (or find it in “Other…”)
Look at the left side of the DDMS perspective and locate the Devices window and select your phone/emulator. Now the LogCat will update and connect to your emulator.