Index: sources/canbus/messagehandler.h
===================================================================
diff -u -rd6c7d6c382fe56e19d132f6ba0bcbbc1e6b2060f -r212de04bcfd9c0ec4c13faca1d4227a8ae30e978
--- sources/canbus/messagehandler.h	(.../messagehandler.h)	(revision d6c7d6c382fe56e19d132f6ba0bcbbc1e6b2060f)
+++ sources/canbus/messagehandler.h	(.../messagehandler.h)	(revision 212de04bcfd9c0ec4c13faca1d4227a8ae30e978)
@@ -44,14 +44,14 @@
  * \brief   The MessageHandler class
  * \details This class is handling the can message by building and striping it.
  * // -- CAN MESSAGE STRUCTURE --
- *   #1  #2  #3  #4  #5  #6  #7  #8
- * +---+---+---+---+---+---+---+---+...........+
+ *   #0  #1  #2  #3  #4  #5  #6  #7
+ * +---+---+---+---+---+---+---+---+--.......--+
  * | A5| MsgId |Len|  Payload  |CRC|..padding..|
- * +---+---+---+---+---+---+---+---+...........+
+ * +---+---+---+---+---+---+---+---+--.......--+
  *  Header Frame:
  *  1 - CRC is last after payload
- *  Ex1 - If Len=0 then CRC is #5
- *  Ex2 - If Len=1 then CRC is #6 and payload is #5
+ *  Ex1 - If Len=0 then CRC is #4
+ *  Ex2 - If Len=1 then CRC is #5 and payload is #4
  *  2 - If CRC is not the last by in the frame
  *  then there is padding 0x00 to make the frame 8 byte fix
  *  Tail Frame:
@@ -65,37 +65,24 @@
     // friends
     friend class ::unittests;
 
-    struct Message {
-        quInt8          length;
-        GuiActionType   actionId;
-        QByteArray      data;
-        bool isFull() {
-            return length == data.length();
-        }
+    const QHash<GuiActionType ,char> payloadLen {
+        {GuiActionType::PowerOff, 0x01},
+        {GuiActionType::Check_In, 0x00}
     };
 
-    typedef QList<Message> MessageList;
-    QHash<Can_Id, MessageList> messages;
-
-    const QMap<GuiActions::GuiActionsType_Enum ,char> payloadLen {
-        {GuiActions::PowerOff, 0x01},
-        {GuiActions::Check_In, 0x00}
-    };
-
     // constants
     enum Payload_Data   : quint8 {
         ePayload_None   = 0x00,
         ePayload_Sync   = 0xA5,
     };
 
     enum Frame_Data : quint8 {
-        eCanFrameLen    =   8,
-        eMaxHeaderData  =   3,
+        eLenCanFrame        =   8,
+        eLenMaxHeaderData   =   3,
 
-        eLenSync        =   1,
-        eLenActionId    =   2,
-        eLenPayload     =   1,
-        eLenChecksum    =   1,
+        eLenSyncByte        =   1,
+        eLenActionId        =   2,
+        eLenLength          =   1,
 
     };
 
@@ -122,46 +109,53 @@
         eChlid_DG_UI    = eChlid_DG_Alarm, ///< No direct channel has been defined between DG&UI, May be required for logging
         eChlid_UI_DG    = eChlid_UI_Sync , ///< No direct channel has been defined between DG&UI, May be required for logging
 
+    };
 
+    struct Message { // Private Data Class
+        quint8        length;
+        GuiActionType actionId;
+        QByteArray    data;
 
+        bool isComplete() { return data.length() == length; }
+        bool isEmpty   () { return data.length() == 0     ; }
     };
+    typedef QList<Message> MessageList;
+    QHash<Can_Id, MessageList> messages;
 
     // Singleton
     SINGLETON_DECL(MessageHandler)
-public:
-    void init();
+    public:
+        void init();
 
 private:
     void connection();
     void checked_in(); // TODO : needs to be renamed and called from the main timer to tell HD, UI is alive
 
     // build message to be sent
     QByteArray buildMessage (GuiActionType vAction  , GuiActionData vData  = GuiActionData::NoData);
-    void       addSyncByte  ( QByteArray  &vPayload );
-    void       addActionId  ( QByteArray  &vPayload , GuiActionType vAction);
-    void       addLegth     ( QByteArray  &vPayload , GuiActionType vAction);
-    void       addPayload   ( QByteArray  &vPayload , GuiActionData vData  = GuiActionData::NoData);
-    void       addChecksum  ( QByteArray  &vPayload );
-    void       addPadding   ( QByteArray  &vPayload );
+    void       addSyncByte  (QByteArray   &vPayload );
+    void       addActionId  (QByteArray   &vPayload , GuiActionType vAction);
+    void       addLegth     (QByteArray   &vPayload , GuiActionType vAction);
+    void       addData      (QByteArray   &vPayload , GuiActionData vData  = GuiActionData::NoData);
+    void       addCRC       (QByteArray   &vPayload );
+    void       addPadding   (QByteArray   &vPayload );
 
-    quint8     checksum     ( QByteArray  &vBytes );
+    quint8     calcCRC      (const QByteArray &vData );
+    bool       checkCRC     (const QByteArray &vData , quint8 vCRC);
 
     // strip message to its parts
-    QByteArray    stripMessage ( const QCanBusFrame &vFrame );
-    bool          hasSyncByte  ( QByteArray  &vPayload );
-    GuiActionType getActionId  ( QByteArray  &vPayload );
-    quint8        getLength    ( QByteArray  &vPayload );
-    QByteArray    getPayload   ( QByteArray  &vPayload );
-    bool          getChecksum  ( QByteArray  &vPayload );
+    QByteArray    stripMessage (const QCanBusFrame &vFrame );
+    bool          hasSyncByte  (QByteArray &vPayload );
+    GuiActionType getActionId  (QByteArray &vPayload );
+    quint8        getLength    (QByteArray &vPayload );
+    QByteArray    getData      (QByteArray &vPayload , quint8 vLen , bool *ok = nullptr );
 
+
     // 0  - command definition
     // 0.0- Can ID
     // 0.1- command id
     // 0.2- command payload length
-
     // 1 - create, frame, schedule, send
-
-
     // 2 - read, categorize, buffer, act
 
 private slots: // Should be private for thread safety and is connected internally.