diff --git a/telegram.rb b/telegram.rb
index 6c77270..d454ba1 100644
--- a/telegram.rb
+++ b/telegram.rb
@@ -62,22 +62,29 @@ class Telegram
 
   # create a query or send telegram for this object
   # query if data is nil, else send data
-  def initialize (object, data=nil)
+  # direction: true = control unit to device, false = device to control unit
+  def initialize (object, data=nil, direction=true)
     # telegram direction: true = control unit to device, false = device to control unit
-    @direction = true
+    @direction = direction
     # cast type: true = query, false = answer
-    @cast = true
+    @cast = direction
     # device node
     @node = 0
     # set object
     @object = object
     # verify data
-    if data==nil or data.empty? then
-      @transmission = QUERY
-      @data = []
+    if direction then
+      if data==nil or data.empty? then
+        @transmission = QUERY
+        @data = []
+      else
+        raise "wrong data length" if LENGTHS[@object] and data.length!=LENGTHS[@object]
+        @transmission = SEND
+        @data = data
+      end
     else
-      raise "wrong data length" if LENGTHS[@object] and data.length!=LENGTHS[@object]
-      @transmission = SEND
+      raise "wrong data length" if data.empty? or (LENGTHS[@object] and data.length>LENGTHS[@object])
+      @transmission = ANSWER
       @data = data
     end
   end