diff --git a/fhem/FHEM/11_OWDevice.pm b/fhem/FHEM/11_OWDevice.pm
index 076eda956..268940990 100644
--- a/fhem/FHEM/11_OWDevice.pm
+++ b/fhem/FHEM/11_OWDevice.pm
@@ -25,6 +25,8 @@
 
 # Todos:
 # - stateFormat via Interface
+# - warum wird jeder Wert 2x geloggt?
+# ==> bitte prüfen ob das an der fehlenden UnDefFn gelegen hat!
 
 package main;
 
@@ -347,7 +349,7 @@ OWDevice_Initialize($)
   $hash->{UndefFn}   = "OWDevice_Undef";
   $hash->{AttrFn}    = "OWDevice_Attr";
 
-  $hash->{AttrList}  = "trimvalues polls interfaces model loglevel:0,1,2,3,4,5 ".  
+  $hash->{AttrList}  = "IODev trimvalues polls interfaces model loglevel:0,1,2,3,4,5 ".  
                        $readingFnAttributes;
 }
 
@@ -763,6 +765,14 @@ OWDevice_Define($$)
   <a name="OWDeviceattr"></a>
   <b>Attributes</b>
   <ul>
+    <a name="IODev"></a> 	 
+    <li>IODev: 	 
+       Set the OWServer device which should be used for sending and receiving data 	 
+       for this OWDevice. Note: Upon startup fhem assigns each OWDevice 	 
+       to the last previously defined OWServer. Thus it is best if you define OWServer 	 
+       and OWDevices in blocks: first define the first OWServer and the OWDevices that 	 
+       belong to it, then continue with the next OWServer and the attached OWDevices, and so on. 	 
+    </li>
     <li>trimvalues: removes leading and trailing whitespace from readings. Default is 1 (on).</li>
     <li>polls: a comma-separated list of readings to poll. This supersedes the list of default readings to poll.</li>
     <li>interfaces: supersedes the interfaces exposed by that device.</li>