diff --git a/examples/knx-linux/CMakeLists.txt b/examples/knx-linux/CMakeLists.txt
index fe87d43..dc7e86f 100644
--- a/examples/knx-linux/CMakeLists.txt
+++ b/examples/knx-linux/CMakeLists.txt
@@ -19,13 +19,19 @@ add_executable(knx-linux
 	../../src/knx/bau.h
 	../../src/knx/bau07B0.cpp 
 	../../src/knx/bau07B0.h
-	../../src/knx/bau27B0.cpp
+        ../../src/knx/bau091A.cpp
+        ../../src/knx/bau091A.h
+        ../../src/knx/bau27B0.cpp
 	../../src/knx/bau27B0.h
 	../../src/knx/bau57B0.cpp
 	../../src/knx/bau57B0.h
 	../../src/knx/bau_systemB.cpp 
 	../../src/knx/bau_systemB.h
-	../../src/knx/bits.cpp 
+        ../../src/knx/bau_systemB_device.cpp
+        ../../src/knx/bau_systemB_device.h
+        ../../src/knx/bau_systemB_coupler.cpp
+        ../../src/knx/bau_systemB_coupler.h
+        ../../src/knx/bits.cpp
 	../../src/knx/bits.h
 	../../src/knx/callback_property.h
 	../../src/knx/cemi_frame.cpp
@@ -40,9 +46,9 @@ add_executable(knx-linux
 	../../src/knx/data_property.cpp 
 	../../src/knx/data_property.h
 	../../src/knx/device_object.cpp 
-	../../src/knx/device_object.h
-	../../src/knx/dpt.cpp
-	../../src/knx/dpt.h
+        ../../src/knx/device_object.h
+        ../../src/knx/dpt.cpp
+        ../../src/knx/dpt.h
 	../../src/knx/dptconvert.cpp
 	../../src/knx/dptconvert.h
         ../../src/knx/function_property.h
diff --git a/examples/knx-linux/main.cpp b/examples/knx-linux/main.cpp
index f835e0e..66b4373 100644
--- a/examples/knx-linux/main.cpp
+++ b/examples/knx-linux/main.cpp
@@ -1,10 +1,7 @@
 #include "knx_facade.h"
 
-#include "knx/bau57B0.h"
-#include "knx/bau27B0.h"
-#include "knx/bau07B0.h"
+#include "knx/bau091A.h"
 
-#include "knx/group_object_table_object.h"
 #include "knx/bits.h"
 #include <time.h>
 #include <stdlib.h>
@@ -34,59 +31,17 @@ bool isSendHidReportPossible()
     return false;
 }
 #if MEDIUM_TYPE == 5
-KnxFacade<LinuxPlatform, Bau57B0> knx;
+KnxFacade<LinuxPlatform, Bau091A> knx;
 #elif MEDIUM_TYPE == 2
-KnxFacade<LinuxPlatform, Bau27B0> knx;
+KnxFacade<LinuxPlatform, Bau2920> knx;
 #else
 #error Only MEDIUM_TYPE IP and RF supported
 #endif
 
-long lastsend = 0;
-
-#define CURR knx.getGroupObject(1)
-#define MAX knx.getGroupObject(2)
-#define MIN knx.getGroupObject(3)
-#define RESET knx.getGroupObject(4)
-
-void measureTemp()
-{
-    long now = millis();
-    if ((now - lastsend) < 10000)
-        return;
-
-    lastsend = now;
-    int r = rand();
-    double currentValue = (r * 1.0) / (RAND_MAX * 1.0);
-    currentValue *= 100;
-    currentValue -= 50;
-    //    currentValue *= (670433.28 + 273);
-    //    currentValue -= 273;
-    println(currentValue);
-    CURR.value(currentValue);
-
-    double max = MAX.value();
-    if (currentValue > max)
-        MAX.value(currentValue);
-
-    if (currentValue < (double)MIN.value())
-        MIN.value(currentValue);
-}
-
-void resetCallback(GroupObject& go)
-{
-    if (go.value())
-    {
-        MAX.valueNoSend(-273.0);
-        MIN.valueNoSend(670433.28);
-    }
-}
-
 void appLoop()
 {
     if (!knx.configured())
         return;
-    
-    measureTemp();
 }
 
 void setup()
@@ -99,18 +54,7 @@ void setup()
 
     if (knx.configured())
     {
-        CURR.dataPointType(Dpt(9, 1));
-        MIN.dataPointType(Dpt(9, 1));
-        MIN.value(670433.28);
-        MAX.dataPointType(Dpt(9, 1));
-        MAX.valueNoSend(-273.0);
-        RESET.dataPointType(Dpt(1, 15));
-        RESET.callback(resetCallback);
-        printf("Timeout: %d\n", knx.paramWord(0));
-        printf("Zykl. senden: %d\n", knx.paramByte(2));
-        printf("Min/Max senden: %d\n", knx.paramByte(3));
-        printf("Aenderung senden: %d\n", knx.paramByte(4));
-        printf("Abgleich %d\n", knx.paramByte(5));
+        printf("configured %d\n", knx.paramByte(5));
     }
     else
         println("not configured");
diff --git a/src/knx/application_layer.cpp b/src/knx/application_layer.cpp
index 36b2ce2..78aa798 100644
--- a/src/knx/application_layer.cpp
+++ b/src/knx/application_layer.cpp
@@ -10,8 +10,7 @@
 
 const SecurityControl ApplicationLayer::noSecurity {.toolAccess=false, .dataSecurity=DataSecurity::none};
 
-ApplicationLayer::ApplicationLayer(AssociationTableObject& assocTable, BusAccessUnit& bau):
-    _assocTable(assocTable),  _bau(bau)
+ApplicationLayer::ApplicationLayer(BusAccessUnit& bau) : _bau(bau)
 {
 }
 
@@ -20,6 +19,11 @@ void ApplicationLayer::transportLayer(TransportLayer& layer)
     _transportLayer = &layer;
 }
 
+void ApplicationLayer::associationTableObject(AssociationTableObject& assocTable)
+{
+    _assocTable = &assocTable;
+}
+
 #pragma region TL Callbacks
 
 void ApplicationLayer::dataGroupIndication(HopCountType hopType, Priority priority, uint16_t tsap, APDU& apdu)
@@ -29,6 +33,9 @@ void ApplicationLayer::dataGroupIndication(HopCountType hopType, Priority priori
 
 void ApplicationLayer::dataGroupIndication(HopCountType hopType, Priority priority, uint16_t tsap, APDU& apdu, const SecurityControl& secCtrl)
 {
+    if (_assocTable == nullptr)
+        return;
+
     uint8_t len = apdu.length();
     uint8_t dataArray[len];
     uint8_t* data = dataArray;
@@ -45,8 +52,8 @@ void ApplicationLayer::dataGroupIndication(HopCountType hopType, Priority priori
     }
 
     uint16_t startIdx = 0;
-    int32_t asap = _assocTable.nextAsap(tsap, startIdx);
-    for (; asap != -1; asap = _assocTable.nextAsap(tsap, startIdx))
+    int32_t asap = _assocTable->nextAsap(tsap, startIdx);
+    for (; asap != -1; asap = _assocTable->nextAsap(tsap, startIdx))
     {
         switch (apdu.type())
         {
@@ -365,12 +372,15 @@ void ApplicationLayer::dataConnectedConfirm(uint16_t tsap, const SecurityControl
 #pragma endregion
 void ApplicationLayer::groupValueReadRequest(AckType ack, uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl& secCtrl)
 {
+    if (_assocTable == nullptr)
+        return;
+
     _savedAsapReadRequest = asap;
     CemiFrame frame(1);
     APDU& apdu = frame.apdu();
     apdu.type(GroupValueRead);
     
-    int32_t value = _assocTable.translateAsap(asap);
+    int32_t value = _assocTable->translateAsap(asap);
     if (value < 0)
         return; // there is no tsap in association table for this asap
     
@@ -928,6 +938,9 @@ void ApplicationLayer::propertyExtDataSend(ApduType type, AckType ack, Priority
 void ApplicationLayer::groupValueSend(ApduType type, AckType ack, uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl,
     uint8_t* data,  uint8_t& dataLength)
 {
+    if (_assocTable == nullptr)
+        return;
+
     CemiFrame frame(dataLength + 1);
     APDU& apdu = frame.apdu();
     apdu.type(type);
@@ -943,7 +956,7 @@ void ApplicationLayer::groupValueSend(ApduType type, AckType ack, uint16_t asap,
         memcpy(apdudata + 1, data, dataLength);
     }
     // no need to check if there is a tsap. This is a response, so the read got trough
-    uint16_t tsap = (uint16_t)_assocTable.translateAsap(asap);
+    uint16_t tsap = (uint16_t)_assocTable->translateAsap(asap);
     dataGroupRequest(ack, hopType, priority, tsap, apdu, secCtrl);
     dataGroupIndication(hopType, priority, tsap, apdu, secCtrl);
 }
diff --git a/src/knx/application_layer.h b/src/knx/application_layer.h
index 4234716..2f4439c 100644
--- a/src/knx/application_layer.h
+++ b/src/knx/application_layer.h
@@ -22,12 +22,14 @@ class ApplicationLayer
      * @param assocTable The AssociationTable is used to translate between asap (i.e. group objects) and group addresses.
      * @param bau methods are called here depending of the content of the APDU
      */
-    ApplicationLayer(AssociationTableObject& assocTable, BusAccessUnit& bau);
+    ApplicationLayer(BusAccessUnit& bau);
     /**
      * Assigns the TransportLayer to which encoded APDU are submitted to.
      */
     void transportLayer(TransportLayer& layer);
 
+    void associationTableObject(AssociationTableObject& assocTable);
+
     // from transport layer
     // Note: without data secure feature, the application layer is just used with SecurtyControl.dataSecurity = none
     // hooks that can be implemented by derived class (e.g. SecureApplicationLayer)
@@ -204,7 +206,7 @@ class ApplicationLayer
     uint16_t _savedAsapReadRequest;
     uint16_t _savedAsapWriteRequest;
     uint16_t _savedAsapResponse;
-    AssociationTableObject& _assocTable;
+    AssociationTableObject* _assocTable = nullptr;
     BusAccessUnit& _bau;
 
     int32_t _connectedTsap = -1;
diff --git a/src/knx/bau07B0.cpp b/src/knx/bau07B0.cpp
index 47c4f34..ce4f056 100644
--- a/src/knx/bau07B0.cpp
+++ b/src/knx/bau07B0.cpp
@@ -8,12 +8,14 @@
 using namespace std;
 
 Bau07B0::Bau07B0(Platform& platform)
-    : BauSystemB(platform),
-      _dlLayer(_deviceObj, _addrTable, _netLayer, _platform)
+    : BauSystemBDevice(platform),
+      _dlLayer(_deviceObj, _netLayer, _platform)
 #ifdef USE_CEMI_SERVER
     , _cemiServer(*this)
 #endif           
 {
+    _dlLayer.groupAddressTable(_addrTable);
+
     _netLayer.dataLinkLayer(_dlLayer);
 #ifdef USE_CEMI_SERVER
     _cemiServer.dataLinkLayer(_dlLayer);
diff --git a/src/knx/bau07B0.h b/src/knx/bau07B0.h
index a886d17..3e10955 100644
--- a/src/knx/bau07B0.h
+++ b/src/knx/bau07B0.h
@@ -1,14 +1,14 @@
 #pragma once
 
 #include "config.h"
-#include "bau_systemB.h"
+#include "bau_systemB_device.h"
 #include "tpuart_data_link_layer.h"
 #include "cemi_server.h"
 #include "cemi_server_object.h"
 
 #ifdef USE_TP
 
-class Bau07B0 : public BauSystemB
+class Bau07B0 : public BauSystemBDevice
 {
   public:
     Bau07B0(Platform& platform);
@@ -26,4 +26,4 @@ class Bau07B0 : public BauSystemB
     CemiServerObject _cemiServerObject;
 #endif                                  
 };
-#endif
\ No newline at end of file
+#endif
diff --git a/src/knx/bau091A.cpp b/src/knx/bau091A.cpp
new file mode 100644
index 0000000..c958bc6
--- /dev/null
+++ b/src/knx/bau091A.cpp
@@ -0,0 +1,121 @@
+#include "config.h"
+#include "bau091A.h"
+#include "bits.h"
+#include <string.h>
+#include <stdio.h>
+
+#ifdef USE_IP
+
+using namespace std;
+
+Bau091A::Bau091A(Platform& platform)
+    : BauSystemBCoupler(platform),
+      _ipParameters(_deviceObj, platform),
+      _dlLayerPrimary(_deviceObj, _ipParameters, _netLayer, _platform),
+      _dlLayerSecondary(_deviceObj, _netLayer, platform)
+#ifdef USE_CEMI_SERVER
+      ,
+      _cemiServer(*this)
+#endif
+{
+    _netLayer.dataLinkLayer(_dlLayerSecondary);
+#ifdef USE_CEMI_SERVER
+    _cemiServer.dataLinkLayer(_dlLayer);
+    _dlLayer.cemiServer(_cemiServer);
+    _memory.addSaveRestore(&_cemiServerObject);
+#endif
+    _memory.addSaveRestore(&_ipParameters);
+
+    // Set Mask Version in Device Object depending on the BAU
+    _deviceObj.maskVersion(0x091A);
+
+    // Set which interface objects are available in the device object
+    // This differs from BAU to BAU with different medium types.
+    // See PID_IO_LIST
+    Property* prop = _deviceObj.property(PID_IO_LIST);
+    prop->write(1, (uint16_t) OT_DEVICE);
+    prop->write(2, (uint16_t) OT_ADDR_TABLE);
+    prop->write(3, (uint16_t) OT_ASSOC_TABLE);
+    prop->write(4, (uint16_t) OT_GRP_OBJ_TABLE);
+    prop->write(5, (uint16_t) OT_APPLICATION_PROG);
+    prop->write(6, (uint16_t) OT_IP_PARAMETER);
+#if defined(USE_DATASECURE) && defined(USE_CEMI_SERVER)
+    prop->write(7, (uint16_t) OT_SECURITY);
+    prop->write(8, (uint16_t) OT_CEMI_SERVER);
+#elif defined(USE_DATASECURE)
+    prop->write(7, (uint16_t) OT_SECURITY);
+#elif defined(USE_CEMI_SERVER)
+    prop->write(7, (uint16_t) OT_CEMI_SERVER);
+#endif
+}
+
+InterfaceObject* Bau091A::getInterfaceObject(uint8_t idx)
+{
+    switch (idx)
+    {
+        case 0:
+            return &_deviceObj;
+        case 4:
+            return &_appProgram;
+        case 5: // would be app_program 2
+            return nullptr;
+        case 6:
+            return &_ipParameters;
+#if defined(USE_DATASECURE) && defined(USE_CEMI_SERVER)
+        case 7:
+            return &_secIfObj;
+        case 8:
+            return &_cemiServerObject;
+#elif defined(USE_CEMI_SERVER)
+        case 7:
+            return &_cemiServerObject;
+#elif defined(USE_DATASECURE)
+        case 7:
+            return &_secIfObj;
+#endif
+        default:
+            return nullptr;
+    }
+}
+
+InterfaceObject* Bau091A::getInterfaceObject(ObjectType objectType, uint8_t objectInstance)
+{
+    // We do not use it right now. 
+    // Required for coupler mode as there are multiple router objects for example
+    (void) objectInstance;
+
+    switch (objectType)
+    {
+        case OT_DEVICE:
+            return &_deviceObj;
+        case OT_APPLICATION_PROG:
+            return &_appProgram;
+        case OT_IP_PARAMETER:
+            return &_ipParameters;
+#ifdef USE_DATASECURE
+        case OT_SECURITY:
+            return &_secIfObj;
+#endif
+#ifdef USE_CEMI_SERVER
+        case OT_CEMI_SERVER:
+            return &_cemiServerObject;
+#endif
+        default:
+            return nullptr;
+    }
+}
+
+void Bau091A::doMasterReset(EraseCode eraseCode, uint8_t channel)
+{
+    // Common SystemB objects
+    BauSystemB::doMasterReset(eraseCode, channel);
+
+    _ipParameters.masterReset(eraseCode, channel);
+}
+
+DataLinkLayer& Bau091A::dataLinkLayer()
+{
+    return _dlLayerSecondary;
+}
+
+#endif
diff --git a/src/knx/bau091A.h b/src/knx/bau091A.h
new file mode 100644
index 0000000..0d1c687
--- /dev/null
+++ b/src/knx/bau091A.h
@@ -0,0 +1,31 @@
+#pragma once
+
+#include "config.h"
+#ifdef USE_IP
+#include "bau_systemB_coupler.h"
+#include "ip_parameter_object.h"
+#include "ip_data_link_layer.h"
+#include "tpuart_data_link_layer.h"
+#include "cemi_server_object.h"
+
+class Bau091A : public BauSystemBCoupler
+{
+  public:
+    Bau091A(Platform& platform);
+
+  protected:
+    InterfaceObject* getInterfaceObject(uint8_t idx);
+    InterfaceObject* getInterfaceObject(ObjectType objectType, uint8_t objectInstance);
+    DataLinkLayer& dataLinkLayer();
+
+    virtual void doMasterReset(EraseCode eraseCode, uint8_t channel) override;
+  private:
+    IpParameterObject _ipParameters;
+    IpDataLinkLayer _dlLayerPrimary;
+    TpUartDataLinkLayer _dlLayerSecondary;
+#ifdef USE_CEMI_SERVER
+    CemiServer _cemiServer;
+    CemiServerObject _cemiServerObject;
+#endif
+};
+#endif
diff --git a/src/knx/bau27B0.cpp b/src/knx/bau27B0.cpp
index 0ef567a..5def14b 100644
--- a/src/knx/bau27B0.cpp
+++ b/src/knx/bau27B0.cpp
@@ -7,8 +7,8 @@
 using namespace std;
 
 Bau27B0::Bau27B0(Platform& platform)
-    : BauSystemB(platform),
-      _dlLayer(_deviceObj, _rfMediumObj, _addrTable, _netLayer, _platform)
+    : BauSystemBDevice(platform),
+      _dlLayer(_deviceObj, _rfMediumObj, _netLayer, _platform)
 #ifdef USE_CEMI_SERVER
     , _cemiServer(*this)
 #endif      
diff --git a/src/knx/bau27B0.h b/src/knx/bau27B0.h
index 63f2844..036d207 100644
--- a/src/knx/bau27B0.h
+++ b/src/knx/bau27B0.h
@@ -2,14 +2,14 @@
 
 #include "config.h"
 #ifdef USE_RF
-#include "bau_systemB.h"
+#include "bau_systemB_device.h"
 #include "rf_medium_object.h"
 #include "rf_physical_layer.h"
 #include "rf_data_link_layer.h"
 #include "cemi_server.h"
 #include "cemi_server_object.h"
 
-class Bau27B0 : public BauSystemB
+class Bau27B0 : public BauSystemBDevice
 {
   public:
     Bau27B0(Platform& platform);
diff --git a/src/knx/bau57B0.cpp b/src/knx/bau57B0.cpp
index eee3cc2..eb37ef0 100644
--- a/src/knx/bau57B0.cpp
+++ b/src/knx/bau57B0.cpp
@@ -9,9 +9,9 @@
 using namespace std;
 
 Bau57B0::Bau57B0(Platform& platform)
-    : BauSystemB(platform),
+    : BauSystemBDevice(platform),
       _ipParameters(_deviceObj, platform),
-      _dlLayer(_deviceObj, _addrTable, _ipParameters, _netLayer, _platform)
+      _dlLayer(_deviceObj, _ipParameters, _netLayer, _platform)
 #ifdef USE_CEMI_SERVER
       ,
       _cemiServer(*this)
diff --git a/src/knx/bau57B0.h b/src/knx/bau57B0.h
index 85c5ca0..1066ab7 100644
--- a/src/knx/bau57B0.h
+++ b/src/knx/bau57B0.h
@@ -2,12 +2,12 @@
 
 #include "config.h"
 #ifdef USE_IP
-#include "bau_systemB.h"
+#include "bau_systemB_device.h"
 #include "ip_parameter_object.h"
 #include "ip_data_link_layer.h"
 #include "cemi_server_object.h"
 
-class Bau57B0 : public BauSystemB
+class Bau57B0 : public BauSystemBDevice
 {
   public:
     Bau57B0(Platform& platform);
diff --git a/src/knx/bau_systemB.cpp b/src/knx/bau_systemB.cpp
index 8d20f59..cedccdc 100644
--- a/src/knx/bau_systemB.cpp
+++ b/src/knx/bau_systemB.cpp
@@ -14,41 +14,17 @@ enum NmReadSerialNumberType
 static constexpr auto kFunctionPropertyResultBufferMaxSize = 64;
 static constexpr auto kRestartProcessTime = 3;
 
-BauSystemB::BauSystemB(Platform& platform): _memory(platform, _deviceObj), _addrTable(_memory),
-    _assocTable(_memory), _groupObjTable(_memory), _appProgram(_memory),
-    _platform(platform),
-#ifdef USE_DATASECURE
-    _appLayer(_deviceObj, _secIfObj, _assocTable, _addrTable, *this),
-#else
-    _appLayer(_assocTable, *this),
-#endif
-    _transLayer(_appLayer, _addrTable), _netLayer(_transLayer)
+BauSystemB::BauSystemB(Platform& platform): _memory(platform, _deviceObj),
+     _appProgram(_memory),
+    _platform(platform)
 {
-#ifdef USE_DATASECURE
-    _secIfObj.secureApplicationLayer(_appLayer);
-#endif
-    _appLayer.transportLayer(_transLayer);
-    _transLayer.networkLayer(_netLayer);
-    _memory.addSaveRestore(&_deviceObj);
     _memory.addSaveRestore(&_appProgram);
-    _memory.addSaveRestore(&_addrTable);
-    _memory.addSaveRestore(&_assocTable);
-    _memory.addSaveRestore(&_groupObjTable);
-#ifdef USE_DATASECURE
-    _memory.addSaveRestore(&_secIfObj);
-#endif
-
 }
 
 void BauSystemB::loop()
 {
     dataLinkLayer().loop();
-    _transLayer.loop();
-    sendNextGroupTelegram();
     nextRestartState();
-#ifdef USE_DATASECURE
-    _appLayer.loop();
-#endif
 }
 
 bool BauSystemB::enabled()
@@ -61,74 +37,6 @@ void BauSystemB::enabled(bool value)
     dataLinkLayer().enabled(value);
 }
 
-void BauSystemB::sendNextGroupTelegram()
-{
-    if(!configured())
-        return;
-    
-    static uint16_t startIdx = 1;
-
-    GroupObjectTableObject& table = _groupObjTable;
-    uint16_t objCount = table.entryCount();
-
-    for (uint16_t asap = startIdx; asap <= objCount; asap++)
-    {
-        GroupObject& go = table.get(asap);
-
-        ComFlag flag = go.commFlag();
-        if (flag != ReadRequest && flag != WriteRequest)
-            continue;
-
-        if (!go.communicationEnable())
-            continue;
-
-        SecurityControl goSecurity;
-        goSecurity.toolAccess = false; // Secured group communication never uses the toolkey. ETS knows all keys, also the group keys.
-
-#ifdef USE_DATASECURE
-        // Get security flags from Security Interface Object for this group object
-        goSecurity.dataSecurity = _secIfObj.getGroupObjectSecurity(asap);
-#else
-        goSecurity.dataSecurity = DataSecurity::none;
-#endif
-
-        if (flag == WriteRequest && go.transmitEnable())
-        {
-            uint8_t* data = go.valueRef();
-            _appLayer.groupValueWriteRequest(AckRequested, asap, go.priority(), NetworkLayerParameter, goSecurity, data,
-                go.sizeInTelegram());
-        }
-        else if (flag == ReadRequest)
-        {
-            _appLayer.groupValueReadRequest(AckRequested, asap, go.priority(), NetworkLayerParameter, goSecurity);
-        }
-
-        go.commFlag(Transmitting);
-
-        startIdx = asap + 1;
-        return;
-    }
-
-    startIdx = 1;
-}
-
-void BauSystemB::updateGroupObject(GroupObject & go, uint8_t * data, uint8_t length)
-{
-    uint8_t* goData = go.valueRef();
-    if (length != go.valueSize())
-    {
-        go.commFlag(Error);
-        return;
-    }
-
-    memcpy(goData, data, length);
-
-    go.commFlag(Updated);
-    GroupObjectUpdatedHandler handler = go.callback();
-    if (handler)
-        handler(go);
-}
-
 void BauSystemB::readMemory()
 {
     _memory.readMemory();
@@ -139,21 +47,16 @@ void BauSystemB::writeMemory()
     _memory.writeMemory();
 }
 
-DeviceObject& BauSystemB::deviceObject()
-{
-    return _deviceObj;
-}
-
-GroupObjectTableObject& BauSystemB::groupObjectTable()
-{
-    return _groupObjTable;
-}
-
 ApplicationProgramObject& BauSystemB::parameters()
 {
     return _appProgram;
 }
 
+DeviceObject& BauSystemB::deviceObject()
+{
+    return _deviceObj;
+}
+
 bool BauSystemB::configured()
 {
     // _configured is set to true initially, if the device was configured with ETS it will be set to true after restart
@@ -161,10 +64,7 @@ bool BauSystemB::configured()
     if (!_configured)
         return false;
     
-    _configured = _groupObjTable.loadState() == LS_LOADED
-        && _addrTable.loadState() == LS_LOADED
-        && _assocTable.loadState() == LS_LOADED
-        && _appProgram.loadState() == LS_LOADED;
+    _configured = _appProgram.loadState() == LS_LOADED;
     
     return _configured;
 }
@@ -233,7 +133,7 @@ void BauSystemB::deviceDescriptorReadIndication(Priority priority, HopCountType
     
     uint8_t data[2];
     pushWord(_deviceObj.maskVersion(), data);
-    _appLayer.deviceDescriptorReadResponse(AckRequested, priority, hopType, asap, secCtrl, descriptorType, data);
+    applicationLayer().deviceDescriptorReadResponse(AckRequested, priority, hopType, asap, secCtrl, descriptorType, data);
 }
 
 void BauSystemB::memoryWriteIndication(Priority priority, HopCountType hopType, uint16_t asap, const SecurityControl &secCtrl, uint8_t number,
@@ -248,7 +148,7 @@ void BauSystemB::memoryWriteIndication(Priority priority, HopCountType hopType,
 void BauSystemB::memoryReadIndication(Priority priority, HopCountType hopType, uint16_t asap, const SecurityControl &secCtrl, uint8_t number,
     uint16_t memoryAddress)
 {
-    _appLayer.memoryReadResponse(AckRequested, priority, hopType, asap, secCtrl, number, memoryAddress,
+    applicationLayer().memoryReadResponse(AckRequested, priority, hopType, asap, secCtrl, number, memoryAddress,
         _memory.toAbsolute(memoryAddress));
 }
 
@@ -256,27 +156,17 @@ void BauSystemB::memoryExtWriteIndication(Priority priority, HopCountType hopTyp
 {
     _memory.writeMemory(memoryAddress, number, data);
 
-    _appLayer.memoryExtWriteResponse(AckRequested, priority, hopType, asap, secCtrl, ReturnCodes::Success, number, memoryAddress, _memory.toAbsolute(memoryAddress));
+    applicationLayer().memoryExtWriteResponse(AckRequested, priority, hopType, asap, secCtrl, ReturnCodes::Success, number, memoryAddress, _memory.toAbsolute(memoryAddress));
 }
 
 void BauSystemB::memoryExtReadIndication(Priority priority, HopCountType hopType, uint16_t asap, const SecurityControl &secCtrl, uint8_t number, uint32_t memoryAddress)
 {
-    _appLayer.memoryExtReadResponse(AckRequested, priority, hopType, asap, secCtrl, ReturnCodes::Success, number, memoryAddress, _memory.toAbsolute(memoryAddress));
+    applicationLayer().memoryExtReadResponse(AckRequested, priority, hopType, asap, secCtrl, ReturnCodes::Success, number, memoryAddress, _memory.toAbsolute(memoryAddress));
 }
 
 void BauSystemB::doMasterReset(EraseCode eraseCode, uint8_t channel)
 {
-    _addrTable.masterReset(eraseCode, channel);
-    _assocTable.masterReset(eraseCode, channel);
-    _groupObjTable.masterReset(eraseCode, channel);
     _appProgram.masterReset(eraseCode, channel);
-#ifdef USE_DATASECURE
-    // If erase code is FactoryReset or FactoryResetWithoutIA, set FDSK as toolkey again
-    // and disable security mode.
-    // FIXME: the A_RestartResponse PDU has still to be sent with the current toolkey.
-    // Idea: use local confirmation of sent A_RestartResponse PDU to trigger writing the FDSK afterwards
-    _secIfObj.masterReset(eraseCode, channel);
-#endif
 }
 
 void BauSystemB::restartRequestIndication(Priority priority, HopCountType hopType, uint16_t asap, const SecurityControl &secCtrl, RestartType restartType, EraseCode eraseCode, uint8_t channel)
@@ -290,7 +180,7 @@ void BauSystemB::restartRequestIndication(Priority priority, HopCountType hopTyp
         uint8_t errorCode = checkmasterResetValidity(eraseCode, channel);
         // We send the restart response now before actually applying the reset values
         // Processing time is kRestartProcessTime (example 3 seconds) that we require for the applying the master reset with restart
-        _appLayer.restartResponse(AckRequested, priority, hopType, secCtrl, errorCode, (errorCode == 0) ? kRestartProcessTime : 0);
+        applicationLayer().restartResponse(AckRequested, priority, hopType, secCtrl, errorCode, (errorCode == 0) ? kRestartProcessTime : 0);
         doMasterReset(eraseCode, channel);
     }
     else
@@ -307,12 +197,12 @@ void BauSystemB::restartRequestIndication(Priority priority, HopCountType hopTyp
 
 void BauSystemB::authorizeIndication(Priority priority, HopCountType hopType, uint16_t asap, const SecurityControl &secCtrl, uint32_t key)
 {
-    _appLayer.authorizeResponse(AckRequested, priority, hopType, asap, secCtrl, 0);
+    applicationLayer().authorizeResponse(AckRequested, priority, hopType, asap, secCtrl, 0);
 }
 
 void BauSystemB::userMemoryReadIndication(Priority priority, HopCountType hopType, uint16_t asap, const SecurityControl &secCtrl, uint8_t number, uint32_t memoryAddress)
 {
-    _appLayer.userMemoryReadResponse(AckRequested, priority, hopType, asap, secCtrl, number, memoryAddress,
+    applicationLayer().userMemoryReadResponse(AckRequested, priority, hopType, asap, secCtrl, number, memoryAddress,
         _memory.toAbsolute(memoryAddress));
 }
 
@@ -336,7 +226,7 @@ void BauSystemB::propertyDescriptionReadIndication(Priority priority, HopCountTy
     if (obj)
         obj->readPropertyDescription(pid, propertyIndex, writeEnable, type, numberOfElements, access);
 
-    _appLayer.propertyDescriptionReadResponse(AckRequested, priority, hopType, asap, secCtrl, objectIndex, pid, propertyIndex,
+    applicationLayer().propertyDescriptionReadResponse(AckRequested, priority, hopType, asap, secCtrl, objectIndex, pid, propertyIndex,
         writeEnable, type, numberOfElements, access);
 }
 
@@ -362,7 +252,7 @@ void BauSystemB::propertyValueExtWriteIndication(Priority priority, HopCountType
 
     if (confirmed)
     {
-        _appLayer.propertyValueExtWriteConResponse(AckRequested, priority, hopType, asap, secCtrl, objectType, objectInstance, propertyId, numberOfElements, startIndex, returnCode);
+        applicationLayer().propertyValueExtWriteConResponse(AckRequested, priority, hopType, asap, secCtrl, objectType, objectInstance, propertyId, numberOfElements, startIndex, returnCode);
     }
 }
 
@@ -390,7 +280,7 @@ void BauSystemB::propertyValueReadIndication(Priority priority, HopCountType hop
     if (elementCount == 0)
         size = 0;
     
-    _appLayer.propertyValueReadResponse(AckRequested, priority, hopType, asap, secCtrl, objectIndex, propertyId, elementCount,
+    applicationLayer().propertyValueReadResponse(AckRequested, priority, hopType, asap, secCtrl, objectIndex, propertyId, elementCount,
                                         startIndex, data, size);
 }
 
@@ -418,7 +308,7 @@ void BauSystemB::propertyValueExtReadIndication(Priority priority, HopCountType
     if (elementCount == 0)
         size = 0;
 
-    _appLayer.propertyValueExtReadResponse(AckRequested, priority, hopType, asap, secCtrl, objectType, objectInstance, propertyId, elementCount,
+    applicationLayer().propertyValueExtReadResponse(AckRequested, priority, hopType, asap, secCtrl, objectType, objectInstance, propertyId, elementCount,
                                            startIndex, data, size);
 }
 
@@ -441,7 +331,7 @@ void BauSystemB::functionPropertyCommandIndication(Priority priority, HopCountTy
         }
     }
 
-    _appLayer.functionPropertyStateResponse(AckRequested, priority, hopType, asap, secCtrl, objectIndex, propertyId, resultData, resultLength);
+    applicationLayer().functionPropertyStateResponse(AckRequested, priority, hopType, asap, secCtrl, objectIndex, propertyId, resultData, resultLength);
 }
 
 void BauSystemB::functionPropertyStateIndication(Priority priority, HopCountType hopType, uint16_t asap, const SecurityControl &secCtrl, uint8_t objectIndex,
@@ -463,7 +353,7 @@ void BauSystemB::functionPropertyStateIndication(Priority priority, HopCountType
         }
     }
 
-    _appLayer.functionPropertyStateResponse(AckRequested, priority, hopType, asap, secCtrl, objectIndex, propertyId, resultData, resultLength);
+    applicationLayer().functionPropertyStateResponse(AckRequested, priority, hopType, asap, secCtrl, objectIndex, propertyId, resultData, resultLength);
 }
 
 void BauSystemB::functionPropertyExtCommandIndication(Priority priority, HopCountType hopType, uint16_t asap, const SecurityControl &secCtrl, ObjectType objectType, uint8_t objectInstance,
@@ -519,7 +409,7 @@ void BauSystemB::functionPropertyExtCommandIndication(Priority priority, HopCoun
         resultData[0] = ReturnCodes::GenericError;
     }
 
-    _appLayer.functionPropertyExtStateResponse(AckRequested, priority, hopType, asap, secCtrl, objectType, objectInstance, propertyId, resultData, resultLength);
+    applicationLayer().functionPropertyExtStateResponse(AckRequested, priority, hopType, asap, secCtrl, objectType, objectInstance, propertyId, resultData, resultLength);
 }
 
 void BauSystemB::functionPropertyExtStateIndication(Priority priority, HopCountType hopType, uint16_t asap, const SecurityControl &secCtrl, ObjectType objectType, uint8_t objectInstance,
@@ -566,13 +456,13 @@ void BauSystemB::functionPropertyExtStateIndication(Priority priority, HopCountT
         resultData[0] = ReturnCodes::GenericError;
     }
 
-    _appLayer.functionPropertyExtStateResponse(AckRequested, priority, hopType, asap, secCtrl, objectType, objectInstance, propertyId, resultData, resultLength);
+    applicationLayer().functionPropertyExtStateResponse(AckRequested, priority, hopType, asap, secCtrl, objectType, objectInstance, propertyId, resultData, resultLength);
 }
 
 void BauSystemB::individualAddressReadIndication(HopCountType hopType, const SecurityControl &secCtrl)
 {
     if (_deviceObj.progMode())
-        _appLayer.individualAddressReadResponse(AckRequested, hopType, secCtrl);
+        applicationLayer().individualAddressReadResponse(AckRequested, hopType, secCtrl);
 }
 
 void BauSystemB::individualAddressWriteIndication(HopCountType hopType, const SecurityControl &secCtrl, uint16_t newaddress)
@@ -598,85 +488,10 @@ void BauSystemB::individualAddressSerialNumberReadIndication(Priority priority,
     if (!memcmp(knxSerialNumber, _deviceObj.propertyData(PID_SERIAL_NUMBER), 6))
     {
         uint8_t emptyDomainAddress[6] = {0x00};
-        _appLayer.IndividualAddressSerialNumberReadResponse(priority, hopType, secCtrl, emptyDomainAddress, knxSerialNumber);
+        applicationLayer().IndividualAddressSerialNumberReadResponse(priority, hopType, secCtrl, emptyDomainAddress, knxSerialNumber);
     }
 }
 
-void BauSystemB::groupValueWriteLocalConfirm(AckType ack, uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl, uint8_t * data, uint8_t dataLength, bool status)
-{
-    GroupObject& go = _groupObjTable.get(asap);
-    if (status)
-        go.commFlag(Ok);
-    else
-        go.commFlag(Error);
-}
-
-void BauSystemB::groupValueReadLocalConfirm(AckType ack, uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl, bool status)
-{
-    GroupObject& go = _groupObjTable.get(asap);
-    if (status)
-        go.commFlag(Ok);
-    else
-        go.commFlag(Error);
-}
-
-void BauSystemB::groupValueReadIndication(uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl)
-{
-#ifdef USE_DATASECURE
-    DataSecurity requiredGoSecurity;
-
-    // Get security flags from Security Interface Object for this group object
-    requiredGoSecurity = _secIfObj.getGroupObjectSecurity(asap);
-
-    if (secCtrl.dataSecurity != requiredGoSecurity)
-    {
-        println("GroupValueRead: access denied due to wrong security flags");
-        return;
-    }
-#endif
-
-    GroupObject& go = _groupObjTable.get(asap);
-
-    if (!go.communicationEnable() || !go.readEnable())
-        return;
-    
-    uint8_t* data = go.valueRef();
-    _appLayer.groupValueReadResponse(AckRequested, asap, priority, hopType, secCtrl, data, go.sizeInTelegram());
-}
-
-void BauSystemB::groupValueReadAppLayerConfirm(uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl, uint8_t* data,
-    uint8_t dataLength)
-{
-    GroupObject& go = _groupObjTable.get(asap);
-
-    if (!go.communicationEnable() || !go.responseUpdateEnable())
-        return;
-
-    updateGroupObject(go, data, dataLength);
-}
-
-void BauSystemB::groupValueWriteIndication(uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl, uint8_t * data, uint8_t dataLength)
-{
-#ifdef USE_DATASECURE
-    DataSecurity requiredGoSecurity;
-
-    // Get security flags from Security Interface Object for this group object
-    requiredGoSecurity = _secIfObj.getGroupObjectSecurity(asap);
-
-    if (secCtrl.dataSecurity != requiredGoSecurity)
-    {
-        println("GroupValueWrite: access denied due to wrong security flags");
-        return;
-    }
-#endif
-    GroupObject& go = _groupObjTable.get(asap);
-
-    if (!go.communicationEnable() || !go.writeEnable())
-        return;
-
-    updateGroupObject(go, data, dataLength);
-}
-
 void BauSystemB::addSaveRestore(SaveRestore* obj)
 {
     _memory.addSaveRestore(obj);
@@ -684,12 +499,12 @@ void BauSystemB::addSaveRestore(SaveRestore* obj)
 
 bool BauSystemB::restartRequest(uint16_t asap, const SecurityControl secCtrl)
 {
-    if (_appLayer.isConnected())
+    if (applicationLayer().isConnected())
         return false;
     _restartState = Connecting; // order important, has to be set BEFORE connectRequest
     _restartSecurity = secCtrl;
-    _appLayer.connectRequest(asap, SystemPriority);
-    _appLayer.deviceDescriptorReadRequest(AckRequested, SystemPriority, NetworkLayerParameter, asap, secCtrl, 0);
+    applicationLayer().connectRequest(asap, SystemPriority);
+    applicationLayer().deviceDescriptorReadRequest(AckRequested, SystemPriority, NetworkLayerParameter, asap, secCtrl, 0);
     return true;
 }
 
@@ -721,7 +536,7 @@ void BauSystemB::nextRestartState()
             /* connection confirmed, we send restartRequest, but we wait a moment (sending ACK etc)... */
             if (millis() - _restartDelay > 30)
             {
-                _appLayer.restartRequest(AckRequested, SystemPriority, NetworkLayerParameter, _restartSecurity);
+                applicationLayer().restartRequest(AckRequested, SystemPriority, NetworkLayerParameter, _restartSecurity);
                 _restartState = Restarted;
                 _restartDelay = millis();
             }
@@ -730,7 +545,7 @@ void BauSystemB::nextRestartState()
             /* restart is finished, we send a discommect */
             if (millis() - _restartDelay > 30)
             {
-                _appLayer.disconnectRequest(SystemPriority);
+                applicationLayer().disconnectRequest(SystemPriority);
                 _restartState = Idle;
             }
         default:
@@ -753,7 +568,7 @@ void BauSystemB::systemNetworkParameterReadIndication(Priority priority, HopCoun
             if (_deviceObj.progMode() && (objectType == OT_DEVICE) && (propertyId == PID_SERIAL_NUMBER))
             {
                 // Send reply. testResult data is KNX serial number
-                _appLayer.systemNetworkParameterReadResponse(priority, hopType, secCtrl, objectType, propertyId,
+                applicationLayer().systemNetworkParameterReadResponse(priority, hopType, secCtrl, objectType, propertyId,
                                                              testInfo, testInfoLength, (uint8_t*)_deviceObj.propertyData(PID_SERIAL_NUMBER), 6);
             }
         break;
diff --git a/src/knx/bau_systemB.h b/src/knx/bau_systemB.h
index b485942..7ae6318 100644
--- a/src/knx/bau_systemB.h
+++ b/src/knx/bau_systemB.h
@@ -2,10 +2,6 @@
 
 #include "config.h"
 #include "bau.h"
-#include "device_object.h"
-#include "address_table_object.h"
-#include "association_table_object.h"
-#include "group_object_table_object.h"
 #include "security_interface_object.h"
 #include "application_program_object.h"
 #include "application_layer.h"
@@ -21,9 +17,8 @@ class BauSystemB : protected BusAccessUnit
   public:
     BauSystemB(Platform& platform);
     virtual void loop();
-    DeviceObject& deviceObject();
-    GroupObjectTableObject& groupObjectTable();
     ApplicationProgramObject& parameters();
+    DeviceObject& deviceObject();
     Memory& memory();
     bool configured();
     bool enabled();
@@ -43,6 +38,8 @@ class BauSystemB : protected BusAccessUnit
 
   protected:
     virtual DataLinkLayer& dataLinkLayer() = 0;
+    virtual ApplicationLayer& applicationLayer() = 0;
+
     void memoryWriteIndication(Priority priority, HopCountType hopType, uint16_t asap, const SecurityControl &secCtrl, uint8_t number,
                                uint16_t memoryAddress, uint8_t* data) override;
     void memoryReadIndication(Priority priority, HopCountType hopType, uint16_t asap, const SecurityControl &secCtrl, uint8_t number,
@@ -80,14 +77,6 @@ class BauSystemB : protected BusAccessUnit
     void individualAddressSerialNumberWriteIndication(Priority priority, HopCountType hopType, const SecurityControl &secCtrl, uint16_t newIndividualAddress,
                                                       uint8_t* knxSerialNumber) override;
     void individualAddressSerialNumberReadIndication(Priority priority, HopCountType hopType, const SecurityControl &secCtrl, uint8_t* knxSerialNumber) override;
-    void groupValueWriteLocalConfirm(AckType ack, uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl,
-                                     uint8_t* data, uint8_t dataLength, bool status) override;
-    void groupValueReadLocalConfirm(AckType ack, uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl, bool status) override;
-    void groupValueReadIndication(uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl) override;
-    void groupValueReadAppLayerConfirm(uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl,
-                                       uint8_t* data, uint8_t dataLength) override;
-    void groupValueWriteIndication(uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl,
-                                   uint8_t* data, uint8_t dataLength) override;
     void systemNetworkParameterReadIndication(Priority priority, HopCountType hopType, const SecurityControl &secCtrl, uint16_t objectType,
                                               uint16_t propertyId, uint8_t* testInfo, uint16_t testinfoLength) override;
     void systemNetworkParameterReadLocalConfirm(Priority priority, HopCountType hopType, const SecurityControl &secCtrl, uint16_t objectType,
@@ -96,8 +85,6 @@ class BauSystemB : protected BusAccessUnit
 
     virtual InterfaceObject* getInterfaceObject(uint8_t idx) = 0;
     virtual InterfaceObject* getInterfaceObject(ObjectType objectType, uint8_t objectInstance) = 0;
-    void sendNextGroupTelegram();
-    void updateGroupObject(GroupObject& go, uint8_t* data, uint8_t length);
     void nextRestartState();
 
     virtual void doMasterReset(EraseCode eraseCode, uint8_t channel);
@@ -110,21 +97,10 @@ class BauSystemB : protected BusAccessUnit
         Restarted
     };
 
-    DeviceObject _deviceObj;
     Memory _memory;
-    AddressTableObject _addrTable;
-    AssociationTableObject _assocTable;
-    GroupObjectTableObject _groupObjTable;
+    DeviceObject _deviceObj;
     ApplicationProgramObject _appProgram;
     Platform& _platform;
-#ifdef USE_DATASECURE
-    SecureApplicationLayer _appLayer;
-    SecurityInterfaceObject _secIfObj;
-#else
-    ApplicationLayer _appLayer;
-#endif
-    TransportLayer _transLayer;
-    NetworkLayer _netLayer;
     bool _configured = true;
     RestartState _restartState = Idle;
     SecurityControl _restartSecurity;
diff --git a/src/knx/bau_systemB_coupler.cpp b/src/knx/bau_systemB_coupler.cpp
new file mode 100644
index 0000000..0f7c1b5
--- /dev/null
+++ b/src/knx/bau_systemB_coupler.cpp
@@ -0,0 +1,57 @@
+#include "bau_systemB_coupler.h"
+#include "bits.h"
+#include <string.h>
+#include <stdio.h>
+
+BauSystemBCoupler::BauSystemBCoupler(Platform& platform) :
+    BauSystemB(platform),
+    _platform(platform),
+#ifdef USE_DATASECURE
+    _appLayer(_deviceObj, _secIfObj, *this),
+#else
+    _appLayer(*this),
+#endif
+    _transLayer(_appLayer), _netLayer(_deviceObj, _transLayer)
+{
+#ifdef USE_DATASECURE
+    _secIfObj.secureApplicationLayer(_appLayer);
+#endif
+    _appLayer.transportLayer(_transLayer);
+    _transLayer.networkLayer(_netLayer);
+    _memory.addSaveRestore(&_deviceObj);
+    _memory.addSaveRestore(&_appProgram);
+#ifdef USE_DATASECURE
+    _memory.addSaveRestore(&_secIfObj);
+#endif
+
+}
+
+ApplicationLayer& BauSystemBCoupler::applicationLayer()
+{
+    return _appLayer;
+}
+
+void BauSystemBCoupler::loop()
+{
+    dataLinkLayer().loop();
+    _transLayer.loop();
+#ifdef USE_DATASECURE
+    _appLayer.loop();
+#endif
+}
+
+bool BauSystemBCoupler::configured()
+{
+    // _configured is set to true initially, if the device was configured with ETS it will be set to true after restart
+    
+    if (!_configured)
+        return false;
+    
+    _configured = _appProgram.loadState() == LS_LOADED;
+    
+    return _configured;
+}
+
+void BauSystemBCoupler::doMasterReset(EraseCode eraseCode, uint8_t channel)
+{
+}
diff --git a/src/knx/bau_systemB_coupler.h b/src/knx/bau_systemB_coupler.h
new file mode 100644
index 0000000..e7b66dd
--- /dev/null
+++ b/src/knx/bau_systemB_coupler.h
@@ -0,0 +1,53 @@
+#pragma once
+
+#include "config.h"
+#include "bau_systemB.h"
+#include "device_object.h"
+#include "address_table_object.h"
+#include "association_table_object.h"
+#include "group_object_table_object.h"
+#include "security_interface_object.h"
+#include "application_program_object.h"
+#include "application_layer.h"
+#include "secure_application_layer.h"
+#include "transport_layer.h"
+#include "network_layer.h"
+#include "data_link_layer.h"
+#include "platform.h"
+#include "memory.h"
+
+class BauSystemBCoupler : public BauSystemB
+{
+  public:
+    BauSystemBCoupler(Platform& platform);
+    virtual void loop();
+    bool configured();
+
+  protected:
+    virtual DataLinkLayer& dataLinkLayer() = 0;
+    virtual ApplicationLayer& applicationLayer() override;
+
+    virtual void doMasterReset(EraseCode eraseCode, uint8_t channel);
+
+    enum RestartState
+    {
+        Idle,
+        Connecting,
+        Connected,
+        Restarted
+    };
+
+    Platform& _platform;
+#ifdef USE_DATASECURE
+    SecureApplicationLayer _appLayer;
+    SecurityInterfaceObject _secIfObj;
+#else
+    ApplicationLayer _appLayer;
+#endif
+    TransportLayer _transLayer;
+    NetworkLayer _netLayer;
+    bool _configured = true;
+    RestartState _restartState = Idle;
+    SecurityControl _restartSecurity;
+    uint32_t _restartDelay = 0;
+};
diff --git a/src/knx/bau_systemB_device.cpp b/src/knx/bau_systemB_device.cpp
new file mode 100644
index 0000000..8f7a574
--- /dev/null
+++ b/src/knx/bau_systemB_device.cpp
@@ -0,0 +1,227 @@
+#include "bau_systemB_device.h"
+#include "bits.h"
+#include <string.h>
+#include <stdio.h>
+
+BauSystemBDevice::BauSystemBDevice(Platform& platform) :
+    BauSystemB(platform),
+    _addrTable(_memory),
+    _assocTable(_memory), _groupObjTable(_memory),
+#ifdef USE_DATASECURE
+    _appLayer(_deviceObj, _secIfObj, *this),
+#else
+    _appLayer(*this),
+#endif
+    _transLayer(_appLayer), _netLayer(_deviceObj, _transLayer)
+{
+#ifdef USE_DATASECURE
+    _secIfObj.secureApplicationLayer(_appLayer);
+#endif
+    _appLayer.transportLayer(_transLayer);
+    _appLayer.associationTableObject(_assocTable);
+    _appLayer.groupAddressTable(_addrTable);
+    _transLayer.networkLayer(_netLayer);
+    _transLayer.groupAddressTable(_addrTable);
+
+    _memory.addSaveRestore(&_deviceObj);
+    _memory.addSaveRestore(&_addrTable);
+    _memory.addSaveRestore(&_assocTable);
+    _memory.addSaveRestore(&_groupObjTable);
+#ifdef USE_DATASECURE
+    _memory.addSaveRestore(&_secIfObj);
+#endif
+}
+
+ApplicationLayer& BauSystemBDevice::applicationLayer()
+{
+    return _appLayer;
+}
+
+void BauSystemBDevice::loop()
+{
+    dataLinkLayer().loop();
+    _transLayer.loop();
+    sendNextGroupTelegram();
+    nextRestartState();
+#ifdef USE_DATASECURE
+    _appLayer.loop();
+#endif
+}
+
+void BauSystemBDevice::sendNextGroupTelegram()
+{
+    if(!configured())
+        return;
+    
+    static uint16_t startIdx = 1;
+
+    GroupObjectTableObject& table = _groupObjTable;
+    uint16_t objCount = table.entryCount();
+
+    for (uint16_t asap = startIdx; asap <= objCount; asap++)
+    {
+        GroupObject& go = table.get(asap);
+
+        ComFlag flag = go.commFlag();
+        if (flag != ReadRequest && flag != WriteRequest)
+            continue;
+
+        if (!go.communicationEnable())
+            continue;
+
+        SecurityControl goSecurity;
+        goSecurity.toolAccess = false; // Secured group communication never uses the toolkey. ETS knows all keys, also the group keys.
+
+#ifdef USE_DATASECURE
+        // Get security flags from Security Interface Object for this group object
+        goSecurity.dataSecurity = _secIfObj.getGroupObjectSecurity(asap);
+#else
+        goSecurity.dataSecurity = DataSecurity::none;
+#endif
+
+        if (flag == WriteRequest && go.transmitEnable())
+        {
+            uint8_t* data = go.valueRef();
+            _appLayer.groupValueWriteRequest(AckRequested, asap, go.priority(), NetworkLayerParameter, goSecurity, data,
+                go.sizeInTelegram());
+        }
+        else if (flag == ReadRequest)
+        {
+            _appLayer.groupValueReadRequest(AckRequested, asap, go.priority(), NetworkLayerParameter, goSecurity);
+        }
+
+        go.commFlag(Transmitting);
+
+        startIdx = asap + 1;
+        return;
+    }
+
+    startIdx = 1;
+}
+
+void BauSystemBDevice::updateGroupObject(GroupObject & go, uint8_t * data, uint8_t length)
+{
+    uint8_t* goData = go.valueRef();
+    if (length != go.valueSize())
+    {
+        go.commFlag(Error);
+        return;
+    }
+
+    memcpy(goData, data, length);
+
+    go.commFlag(Updated);
+    GroupObjectUpdatedHandler handler = go.callback();
+    if (handler)
+        handler(go);
+}
+
+GroupObjectTableObject& BauSystemBDevice::groupObjectTable()
+{
+    return _groupObjTable;
+}
+
+bool BauSystemBDevice::configured()
+{
+    // _configured is set to true initially, if the device was configured with ETS it will be set to true after restart
+    
+    if (!_configured)
+        return false;
+    
+    _configured = _groupObjTable.loadState() == LS_LOADED
+        && _addrTable.loadState() == LS_LOADED
+        && _assocTable.loadState() == LS_LOADED
+        && _appProgram.loadState() == LS_LOADED;
+    
+    return _configured;
+}
+
+void BauSystemBDevice::doMasterReset(EraseCode eraseCode, uint8_t channel)
+{
+    _addrTable.masterReset(eraseCode, channel);
+    _assocTable.masterReset(eraseCode, channel);
+    _groupObjTable.masterReset(eraseCode, channel);
+    _appProgram.masterReset(eraseCode, channel);
+#ifdef USE_DATASECURE
+    // If erase code is FactoryReset or FactoryResetWithoutIA, set FDSK as toolkey again
+    // and disable security mode.
+    // FIXME: the A_RestartResponse PDU has still to be sent with the current toolkey.
+    // Idea: use local confirmation of sent A_RestartResponse PDU to trigger writing the FDSK afterwards
+    _secIfObj.masterReset(eraseCode, channel);
+#endif
+}
+
+void BauSystemBDevice::groupValueWriteLocalConfirm(AckType ack, uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl, uint8_t * data, uint8_t dataLength, bool status)
+{
+    GroupObject& go = _groupObjTable.get(asap);
+    if (status)
+        go.commFlag(Ok);
+    else
+        go.commFlag(Error);
+}
+
+void BauSystemBDevice::groupValueReadLocalConfirm(AckType ack, uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl, bool status)
+{
+    GroupObject& go = _groupObjTable.get(asap);
+    if (status)
+        go.commFlag(Ok);
+    else
+        go.commFlag(Error);
+}
+
+void BauSystemBDevice::groupValueReadIndication(uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl)
+{
+#ifdef USE_DATASECURE
+    DataSecurity requiredGoSecurity;
+
+    // Get security flags from Security Interface Object for this group object
+    requiredGoSecurity = _secIfObj.getGroupObjectSecurity(asap);
+
+    if (secCtrl.dataSecurity != requiredGoSecurity)
+    {
+        println("GroupValueRead: access denied due to wrong security flags");
+        return;
+    }
+#endif
+
+    GroupObject& go = _groupObjTable.get(asap);
+
+    if (!go.communicationEnable() || !go.readEnable())
+        return;
+    
+    uint8_t* data = go.valueRef();
+    _appLayer.groupValueReadResponse(AckRequested, asap, priority, hopType, secCtrl, data, go.sizeInTelegram());
+}
+
+void BauSystemBDevice::groupValueReadAppLayerConfirm(uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl, uint8_t* data,
+    uint8_t dataLength)
+{
+    GroupObject& go = _groupObjTable.get(asap);
+
+    if (!go.communicationEnable() || !go.responseUpdateEnable())
+        return;
+
+    updateGroupObject(go, data, dataLength);
+}
+
+void BauSystemBDevice::groupValueWriteIndication(uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl, uint8_t * data, uint8_t dataLength)
+{
+#ifdef USE_DATASECURE
+    DataSecurity requiredGoSecurity;
+
+    // Get security flags from Security Interface Object for this group object
+    requiredGoSecurity = _secIfObj.getGroupObjectSecurity(asap);
+
+    if (secCtrl.dataSecurity != requiredGoSecurity)
+    {
+        println("GroupValueWrite: access denied due to wrong security flags");
+        return;
+    }
+#endif
+    GroupObject& go = _groupObjTable.get(asap);
+
+    if (!go.communicationEnable() || !go.writeEnable())
+        return;
+
+    updateGroupObject(go, data, dataLength);
+}
diff --git a/src/knx/bau_systemB_device.h b/src/knx/bau_systemB_device.h
new file mode 100644
index 0000000..29daac6
--- /dev/null
+++ b/src/knx/bau_systemB_device.h
@@ -0,0 +1,56 @@
+#pragma once
+
+#include "config.h"
+#include "bau_systemB.h"
+#include "device_object.h"
+#include "address_table_object.h"
+#include "association_table_object.h"
+#include "group_object_table_object.h"
+#include "security_interface_object.h"
+#include "application_program_object.h"
+#include "application_layer.h"
+#include "secure_application_layer.h"
+#include "transport_layer.h"
+#include "network_layer.h"
+#include "data_link_layer.h"
+#include "platform.h"
+#include "memory.h"
+
+class BauSystemBDevice : public BauSystemB
+{
+  public:
+    BauSystemBDevice(Platform& platform);
+    virtual void loop();
+    GroupObjectTableObject& groupObjectTable();
+    Memory& memory();
+    bool configured();
+
+  protected:
+    virtual ApplicationLayer& applicationLayer() override;
+
+    void groupValueWriteLocalConfirm(AckType ack, uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl,
+                                     uint8_t* data, uint8_t dataLength, bool status) override;
+    void groupValueReadLocalConfirm(AckType ack, uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl, bool status) override;
+    void groupValueReadIndication(uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl) override;
+    void groupValueReadAppLayerConfirm(uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl,
+                                       uint8_t* data, uint8_t dataLength) override;
+    void groupValueWriteIndication(uint16_t asap, Priority priority, HopCountType hopType, const SecurityControl &secCtrl,
+                                   uint8_t* data, uint8_t dataLength) override;
+
+    void sendNextGroupTelegram();
+    void updateGroupObject(GroupObject& go, uint8_t* data, uint8_t length);
+
+    virtual void doMasterReset(EraseCode eraseCode, uint8_t channel);
+
+    AddressTableObject _addrTable;
+    AssociationTableObject _assocTable;
+    GroupObjectTableObject _groupObjTable;
+#ifdef USE_DATASECURE
+    SecureApplicationLayer _appLayer;
+    SecurityInterfaceObject _secIfObj;
+#else
+    ApplicationLayer _appLayer;
+#endif
+    TransportLayer _transLayer;
+    NetworkLayer _netLayer;
+};
diff --git a/src/knx/data_link_layer.cpp b/src/knx/data_link_layer.cpp
index 877783d..1d518f5 100644
--- a/src/knx/data_link_layer.cpp
+++ b/src/knx/data_link_layer.cpp
@@ -6,9 +6,8 @@
 #include "address_table_object.h"
 #include "cemi_server.h"
 
-DataLinkLayer::DataLinkLayer(DeviceObject& devObj, AddressTableObject& addrTab, 
-    NetworkLayer& layer, Platform& platform) :
-    _deviceObject(devObj), _groupAddressTable(addrTab),  _networkLayer(layer), _platform(platform)
+DataLinkLayer::DataLinkLayer(DeviceObject& devObj, NetworkLayer& layer, Platform& platform) :
+    _deviceObject(devObj), _networkLayer(layer), _platform(platform)
 {
 }
 
@@ -115,18 +114,6 @@ void DataLinkLayer::frameRecieved(CemiFrame& frame)
     }
     else
     {
-        if (addrType == InduvidualAddress && destination != _deviceObject.induvidualAddress())
-            return;
-
-        if (addrType == GroupAddress && !_groupAddressTable.contains(destination))
-            return;
-
-//        if (frame.npdu().octetCount() > 0)
-//        {
-//            _print("-> DLL ");
-//            frame.apdu().printPDU();
-//        }
-
         _networkLayer.dataIndication(ack, addrType, destination, type, npdu, priority, source);
     }
 }
diff --git a/src/knx/data_link_layer.h b/src/knx/data_link_layer.h
index 28ba679..be19402 100644
--- a/src/knx/data_link_layer.h
+++ b/src/knx/data_link_layer.h
@@ -4,7 +4,6 @@
 
 #include <stdint.h>
 #include "device_object.h"
-#include "address_table_object.h"
 #include "knx_types.h"
 #include "network_layer.h"
 #include "cemi_server.h"
@@ -12,7 +11,7 @@
 class DataLinkLayer
 {
   public:
-    DataLinkLayer(DeviceObject& devObj, AddressTableObject& addrTab, NetworkLayer& layer,
+    DataLinkLayer(DeviceObject& devObj, NetworkLayer& layer,
                   Platform& platform);
 
 #ifdef USE_CEMI_SERVER
@@ -36,7 +35,6 @@ class DataLinkLayer
     virtual bool sendFrame(CemiFrame& frame) = 0;
     uint8_t* frameData(CemiFrame& frame);
     DeviceObject& _deviceObject;
-    AddressTableObject& _groupAddressTable;
     NetworkLayer& _networkLayer;
     Platform& _platform;
 #ifdef USE_CEMI_SERVER
diff --git a/src/knx/ip_data_link_layer.cpp b/src/knx/ip_data_link_layer.cpp
index 13fbdfa..5a9657d 100644
--- a/src/knx/ip_data_link_layer.cpp
+++ b/src/knx/ip_data_link_layer.cpp
@@ -5,7 +5,6 @@
 #include "bits.h"
 #include "platform.h"
 #include "device_object.h"
-#include "address_table_object.h"
 #include "knx_ip_routing_indication.h"
 #include "knx_ip_search_request.h"
 #include "knx_ip_search_response.h"
@@ -18,8 +17,8 @@
 
 #define MIN_LEN_CEMI 10
 
-IpDataLinkLayer::IpDataLinkLayer(DeviceObject& devObj, AddressTableObject& addrTab, IpParameterObject& ipParam, 
-    NetworkLayer& layer, Platform& platform) : DataLinkLayer(devObj, addrTab, layer, platform), _ipParameters(ipParam)
+IpDataLinkLayer::IpDataLinkLayer(DeviceObject& devObj, IpParameterObject& ipParam,
+    NetworkLayer& layer, Platform& platform) : DataLinkLayer(devObj, layer, platform), _ipParameters(ipParam)
 {
 }
 
diff --git a/src/knx/ip_data_link_layer.h b/src/knx/ip_data_link_layer.h
index 11c0fca..ee9acbc 100644
--- a/src/knx/ip_data_link_layer.h
+++ b/src/knx/ip_data_link_layer.h
@@ -11,7 +11,7 @@ class IpDataLinkLayer : public DataLinkLayer
     using DataLinkLayer::_deviceObject;
 
   public:
-    IpDataLinkLayer(DeviceObject& devObj, AddressTableObject& addrTab, IpParameterObject& ipParam, NetworkLayer& layer,
+    IpDataLinkLayer(DeviceObject& devObj, IpParameterObject& ipParam, NetworkLayer& layer,
                     Platform& platform);
 
     void loop();
@@ -25,4 +25,4 @@ class IpDataLinkLayer : public DataLinkLayer
 
     IpParameterObject& _ipParameters;
 };
-#endif
\ No newline at end of file
+#endif
diff --git a/src/knx/network_layer.cpp b/src/knx/network_layer.cpp
index 869c4fc..87ad919 100644
--- a/src/knx/network_layer.cpp
+++ b/src/knx/network_layer.cpp
@@ -4,7 +4,7 @@
 #include "data_link_layer.h"
 #include "bits.h"
 
-NetworkLayer::NetworkLayer(TransportLayer& layer): _transportLayer(layer)
+NetworkLayer::NetworkLayer(DeviceObject &deviceObj, TransportLayer& layer): _transportLayer(layer), _deviceObj(deviceObj)
 {
 
 }
@@ -27,6 +27,21 @@ void NetworkLayer::hopCount(uint8_t value)
 void NetworkLayer::dataIndication(AckType ack, AddressType addrType, uint16_t destination, FrameFormat format, NPDU& npdu, Priority priority, uint16_t source)
 {
     HopCountType hopType = npdu.hopCount() == 7 ? UnlimitedRouting : NetworkLayerParameter;
+
+    // Only for devices which are not a coupler
+    if (addrType == InduvidualAddress && destination != _deviceObj.induvidualAddress())
+        return;
+
+    // TODO: remove. getTSAP() will return 0 later anyway. Get rid of dependency to GAT
+    //if (addrType == GroupAddress && !_groupAddressTable.contains(destination))
+    //    return;
+
+//        if (frame.npdu().octetCount() > 0)
+//        {
+//            _print("-> DLL ");
+//            frame.apdu().printPDU();
+//        }
+
     if (addrType == InduvidualAddress)
     {
         //if (npdu.octetCount() > 0)
diff --git a/src/knx/network_layer.h b/src/knx/network_layer.h
index 0b1f88e..6a8202e 100644
--- a/src/knx/network_layer.h
+++ b/src/knx/network_layer.h
@@ -5,11 +5,12 @@
 #include "npdu.h"
 #include "transport_layer.h"
 class DataLinkLayer;
+class DeviceObject;
 
 class NetworkLayer
 {
   public:
-    NetworkLayer(TransportLayer& layer);
+    NetworkLayer(DeviceObject& deviceObj, TransportLayer& layer);
 
     void dataLinkLayer(DataLinkLayer& layer);
     uint8_t hopCount() const;
@@ -38,4 +39,6 @@ class NetworkLayer
     uint8_t _hopCount = 6;
     DataLinkLayer* _dataLinkLayer = 0;
     TransportLayer& _transportLayer;
+    DeviceObject& _deviceObj;
+
 };
diff --git a/src/knx/rf_data_link_layer.cpp b/src/knx/rf_data_link_layer.cpp
index 0c06de1..48648a8 100644
--- a/src/knx/rf_data_link_layer.cpp
+++ b/src/knx/rf_data_link_layer.cpp
@@ -73,9 +73,9 @@ bool RfDataLinkLayer::sendFrame(CemiFrame& frame)
     return true;
 }
 
-RfDataLinkLayer::RfDataLinkLayer(DeviceObject& devObj, RfMediumObject& rfMediumObj, AddressTableObject& addrTab,
+RfDataLinkLayer::RfDataLinkLayer(DeviceObject& devObj, RfMediumObject& rfMediumObj,
                                          NetworkLayer& layer, Platform& platform)
-    : DataLinkLayer(devObj, addrTab, layer, platform),
+    : DataLinkLayer(devObj, layer, platform),
       _rfMediumObj(rfMediumObj),
       _rfPhy(*this, platform)
 {
@@ -377,4 +377,4 @@ void RfDataLinkLayer::loadNextTxFrame(uint8_t** sendBuffer, uint16_t* sendBuffer
     delete tx_frame;
 }
 
-#endif
\ No newline at end of file
+#endif
diff --git a/src/knx/rf_data_link_layer.h b/src/knx/rf_data_link_layer.h
index 5508fdd..6232ab5 100644
--- a/src/knx/rf_data_link_layer.h
+++ b/src/knx/rf_data_link_layer.h
@@ -16,12 +16,11 @@ class RfDataLinkLayer : public DataLinkLayer
     friend class RfPhysicalLayer;
 
     using DataLinkLayer::_deviceObject;
-    using DataLinkLayer::_groupAddressTable;
     using DataLinkLayer::_platform;
 
   public:
-    RfDataLinkLayer(DeviceObject& devObj, RfMediumObject& rfMediumObj, AddressTableObject& addrTab, NetworkLayer& layer,
-                        Platform& platform);
+    RfDataLinkLayer(DeviceObject& devObj, RfMediumObject& rfMediumObj, NetworkLayer& layer,
+                    Platform& platform);
 
     void loop();
     void enabled(bool value);
@@ -60,4 +59,4 @@ class RfDataLinkLayer : public DataLinkLayer
     uint16_t calcCrcRF(uint8_t* buffer, uint32_t offset, uint32_t len);
 };
 
-#endif
\ No newline at end of file
+#endif
diff --git a/src/knx/secure_application_layer.cpp b/src/knx/secure_application_layer.cpp
index a5dfbc1..ff4901f 100644
--- a/src/knx/secure_application_layer.cpp
+++ b/src/knx/secure_application_layer.cpp
@@ -23,18 +23,25 @@ static constexpr uint8_t kSecureDataPdu = 0;
 static constexpr uint8_t kSecureSyncRequest = 2;
 static constexpr uint8_t kSecureSyncResponse = 3;
 
-SecureApplicationLayer::SecureApplicationLayer(DeviceObject &deviceObj, SecurityInterfaceObject &secIfObj, AssociationTableObject& assocTable, AddressTableObject &addrTab, BusAccessUnit& bau):
-    ApplicationLayer(assocTable, bau),
+SecureApplicationLayer::SecureApplicationLayer(DeviceObject &deviceObj, SecurityInterfaceObject &secIfObj, BusAccessUnit& bau):
+    ApplicationLayer(bau),
     _secIfObj(secIfObj),
-    _deviceObj(deviceObj),
-    _addrTab(addrTab)
+    _deviceObj(deviceObj)
 {
 }
 
+void SecureApplicationLayer::groupAddressTable(AddressTableObject &addrTable)
+{
+    _addrTab = &addrTable;
+}
+
 /* from transport layer */
 
 void SecureApplicationLayer::dataGroupIndication(HopCountType hopType, Priority priority, uint16_t tsap, APDU& apdu)
 {
+    if (_addrTab == nullptr)
+        return;
+
     println("dataGroupIndication");
 
     if (apdu.type() == SecureService)
@@ -293,12 +300,15 @@ void SecureApplicationLayer::dataConnectedConfirm(uint16_t tsap)
 
 void SecureApplicationLayer::dataGroupRequest(AckType ack, HopCountType hopType, Priority priority, uint16_t tsap, APDU& apdu, const SecurityControl& secCtrl)
 {
+    if (_addrTab == nullptr)
+        return;
+
     println("dataGroupRequest");
 
     if (secCtrl.dataSecurity != DataSecurity::none)
     {
         apdu.frame().sourceAddress(_deviceObj.induvidualAddress());
-        apdu.frame().destinationAddress(_addrTab.getGroupAddress(tsap));
+        apdu.frame().destinationAddress(_addrTab->getGroupAddress(tsap));
         apdu.frame().addressType(GroupAddress);
 
         uint16_t secureApduLength = apdu.length() + 3 + 6 + 4; // 3(TPCI,APCI,SCF) + sizeof(seqNum) + apdu.length() + 4
@@ -507,7 +517,10 @@ void SecureApplicationLayer::blockCtr0(uint8_t* buffer, uint8_t* seqNum, uint16_
 
 uint16_t SecureApplicationLayer::groupAddressIndex(uint16_t groupAddr)
 {
-    return _addrTab.getTsap(groupAddr);
+    // Just for safety reasons, we should never get here, because the dataGroupIndication will return already return early without doing anything
+    if (_addrTab == nullptr)
+        return 0;
+    return _addrTab->getTsap(groupAddr);
 }
 
 const uint8_t* SecureApplicationLayer::securityKey(uint16_t addr, bool isGroupAddress)
diff --git a/src/knx/secure_application_layer.h b/src/knx/secure_application_layer.h
index 856904e..0df8f2c 100644
--- a/src/knx/secure_application_layer.h
+++ b/src/knx/secure_application_layer.h
@@ -28,7 +28,9 @@ class SecureApplicationLayer :  public ApplicationLayer
      * @param assocTable The AssociationTable is used to translate between asap (i.e. group objects) and group addresses.
      * @param bau methods are called here depending of the content of the APDU
      */
-    SecureApplicationLayer(DeviceObject& deviceObj, SecurityInterfaceObject& secIfObj, AssociationTableObject& assocTable, AddressTableObject& addrTab, BusAccessUnit& bau);
+    SecureApplicationLayer(DeviceObject& deviceObj, SecurityInterfaceObject& secIfObj, BusAccessUnit& bau);
+
+    void groupAddressTable(AddressTableObject& addrTable);
 
     void clearFailureLog();
     void getFailureCounters(uint8_t* data);
@@ -150,5 +152,5 @@ class SecureApplicationLayer :  public ApplicationLayer
 
     SecurityInterfaceObject& _secIfObj;
     DeviceObject& _deviceObj;
-    AddressTableObject& _addrTab;
+    AddressTableObject* _addrTab = nullptr;
 };
diff --git a/src/knx/tpuart_data_link_layer.cpp b/src/knx/tpuart_data_link_layer.cpp
index c68db25..6e19d5c 100644
--- a/src/knx/tpuart_data_link_layer.cpp
+++ b/src/knx/tpuart_data_link_layer.cpp
@@ -265,23 +265,39 @@ void TpUartDataLinkLayer::loop()
                 if (!_isEcho)
                 {
                     uint8_t c = 0x10;
-                    //ceck if individual or group address
-                    if ((buffer[6] & 0x80) == 0)
+
+                    // If this is not a nullptr we consider this a device to be a coupler
+                    // TODO: Improve for coupler mode, only ACK according to filter tables
+                    if (_groupAddressTable)
                     {
+                        //check if individual or group address
+                        if ((buffer[6] & 0x80) == 0)
+                        {
+                            //individual
+                            if (_deviceObject.induvidualAddress() == getWord(buffer + 4))
+                            {
+                                c |= 0x01;
+                            }
+                        }
+                        else
+                        {
+                            //group
+                            if (_groupAddressTable->contains(getWord(buffer + 4)) || getWord(buffer + 4) == 0)
+                            {
+                                c |= 0x01;
+                            }
+                        }
+                    }
+                    else
+                    {
+                        // TODO: test for only our coupler
                         //individual
                         if (_deviceObject.induvidualAddress() == getWord(buffer + 4))
                         {
                             c |= 0x01;
                         }
                     }
-                    else
-                    {
-                        //group
-                        if (_groupAddressTable.contains(getWord(buffer + 4)) || getWord(buffer + 4) == 0)
-                        {
-                            c |= 0x01;
-                        }
-                    }
+
                     _platform.writeUart(c);
                 }
             }
@@ -412,12 +428,17 @@ void TpUartDataLinkLayer::stopChip()
 #endif
 }
 
-TpUartDataLinkLayer::TpUartDataLinkLayer(DeviceObject& devObj, AddressTableObject& addrTab,
+TpUartDataLinkLayer::TpUartDataLinkLayer(DeviceObject& devObj,
                                          NetworkLayer& layer, Platform& platform)
-    : DataLinkLayer(devObj, addrTab, layer, platform)
+    : DataLinkLayer(devObj, layer, platform)
 {
 }
 
+void TpUartDataLinkLayer::groupAddressTable(AddressTableObject &addrTable)
+{
+    _groupAddressTable = &addrTable;
+}
+
 void TpUartDataLinkLayer::frameBytesReceived(uint8_t* buffer, uint16_t length)
 {
     //printHex("=>", buffer, length);
@@ -548,4 +569,4 @@ void TpUartDataLinkLayer::loadNextTxFrame()
     }
     delete tx_frame;
 }
-#endif
\ No newline at end of file
+#endif
diff --git a/src/knx/tpuart_data_link_layer.h b/src/knx/tpuart_data_link_layer.h
index e84bc3e..dd7c593 100644
--- a/src/knx/tpuart_data_link_layer.h
+++ b/src/knx/tpuart_data_link_layer.h
@@ -11,13 +11,15 @@
 class TpUartDataLinkLayer : public DataLinkLayer
 {
     using DataLinkLayer::_deviceObject;
-    using DataLinkLayer::_groupAddressTable;
     using DataLinkLayer::_platform;
 
   public:
-    TpUartDataLinkLayer(DeviceObject& devObj, AddressTableObject& addrTab, NetworkLayer& layer,
+    TpUartDataLinkLayer(DeviceObject& devObj, NetworkLayer& layer,
                         Platform& platform);
 
+    ;
+    void groupAddressTable(AddressTableObject& addrTable);
+
     void loop();
     void enabled(bool value);
     bool enabled() const;
@@ -62,5 +64,7 @@ class TpUartDataLinkLayer : public DataLinkLayer
     void dataConBytesReceived(uint8_t* buffer, uint16_t length, bool success);
     bool resetChip();
     void stopChip();
+
+    AddressTableObject* _groupAddressTable = nullptr;
 };
-#endif
\ No newline at end of file
+#endif
diff --git a/src/knx/transport_layer.cpp b/src/knx/transport_layer.cpp
index 176ff74..1e3a7f8 100644
--- a/src/knx/transport_layer.cpp
+++ b/src/knx/transport_layer.cpp
@@ -7,8 +7,8 @@
 #include "bits.h"
 #include <stdio.h>
 
-TransportLayer::TransportLayer(ApplicationLayer& layer, AddressTableObject& gat): _savedFrame(0), 
-    _savedFrameConnecting(0), _applicationLayer(layer), _groupAddressTable(gat)
+TransportLayer::TransportLayer(ApplicationLayer& layer): _savedFrame(0),
+    _savedFrameConnecting(0), _applicationLayer(layer)
 {
     _currentState = Closed;
 }
@@ -18,6 +18,11 @@ void TransportLayer::networkLayer(NetworkLayer& layer)
     _networkLayer = &layer;
 }
 
+void TransportLayer::groupAddressTable(AddressTableObject &addrTable)
+{
+    _groupAddressTable = &addrTable;
+}
+
 void TransportLayer::dataIndividualIndication(uint16_t destination, HopCountType hopType, Priority priority, uint16_t source, TPDU& tpdu)
 {
     //if (tpdu.apdu().length() > 0)
@@ -361,7 +366,10 @@ void TransportLayer::dataIndividualConfirm(AckType ack, uint16_t destination, Ho
 
 void TransportLayer::dataGroupIndication(uint16_t destination, HopCountType hopType, Priority priority, uint16_t source, TPDU& tpdu)
 {
-    uint16_t tsap = _groupAddressTable.getTsap(destination);
+    if (_groupAddressTable == nullptr)
+        return;
+
+    uint16_t tsap = _groupAddressTable->getTsap(destination);
     if (tsap == 0)
         return;
     
@@ -395,7 +403,10 @@ void TransportLayer::dataSystemBroadcastConfirm(AckType ack, HopCountType hopTyp
 
 void TransportLayer::dataGroupRequest(AckType ack, HopCountType hopType, Priority priority, uint16_t tsap, APDU& apdu)
 {
-    uint16_t groupAdress = _groupAddressTable.getGroupAddress(tsap);
+    if (_groupAddressTable == nullptr)
+        return;
+
+    uint16_t groupAdress = _groupAddressTable->getGroupAddress(tsap);
     TPDU& tpdu = apdu.frame().tpdu();
     _networkLayer->dataGroupRequest(ack, groupAdress, hopType, priority, tpdu);
 }
diff --git a/src/knx/transport_layer.h b/src/knx/transport_layer.h
index 76bf861..8814cc3 100644
--- a/src/knx/transport_layer.h
+++ b/src/knx/transport_layer.h
@@ -16,8 +16,9 @@ enum StateType { Closed, OpenIdle, OpenWait, Connecting };
 class TransportLayer
 {
 public:
-    TransportLayer(ApplicationLayer& layer, AddressTableObject& gat);
+    TransportLayer(ApplicationLayer& layer);
     void networkLayer(NetworkLayer& layer);
+    void groupAddressTable(AddressTableObject& addrTable);
 
 #pragma region from network layer
     void dataIndividualIndication(uint16_t destination, HopCountType hopType, Priority priority, uint16_t source, TPDU& tpdu);
@@ -115,6 +116,6 @@ private:
     uint8_t _maxRepCount = 3;
 #pragma endregion
     ApplicationLayer& _applicationLayer;
-    AddressTableObject& _groupAddressTable;
+    AddressTableObject* _groupAddressTable;
     NetworkLayer* _networkLayer;
 };
diff --git a/src/knx_facade.h b/src/knx_facade.h
index 923195f..6db2ae2 100644
--- a/src/knx_facade.h
+++ b/src/knx_facade.h
@@ -27,6 +27,7 @@
    #include "linux_platform.h"
    #include "knx/bau57B0.h"
    #include "knx/bau27B0.h"
+   #include "knx/bau091A.h"
 #endif
 
 void buttonUp();