diff --git a/SilKit/include/silkit/capi/Flexray.h b/SilKit/include/silkit/capi/Flexray.h
index 038cf5c27..528f5b37f 100644
--- a/SilKit/include/silkit/capi/Flexray.h
+++ b/SilKit/include/silkit/capi/Flexray.h
@@ -216,12 +216,6 @@ struct SilKit_FlexrayNodeParameters
     //! Maximum permissible rate correction value (range 3-3846 MicroTicks).
     SilKit_FlexrayMicroTick pRateCorrectionOut;
 
-    ////! Not used by network simulator
-    // pSecondKeySlotID
-
-    ////! Not used by network simulator
-    // pTwoKeySlotMode
-
     //! Channel used by the node to send a wakeup pattern (values FlexrayChannel::A, FlexrayChannel::B).
     SilKit_FlexrayChannel pWakeupChannel;
 
@@ -242,6 +236,15 @@ struct SilKit_FlexrayNodeParameters
 
     //! Number of samples per MicroTick (values 1 or 2).
     uint8_t pSamplesPerMicrotick;
+
+    // ----------------------------------------------------------------------
+    // Parameters according to B.3.2.1 (added in SIL Kit 5.0.3)
+    
+    //! Second Key Slot ID of the key slot (range 0-1023, value 0 means that there is no key slot).
+    uint16_t pSecondKeySlotId;
+
+    //! Second Key slot is used for startup with a single cold start node (range 0, 1).
+    uint8_t pTwoKeySlotMode;
 };
 typedef struct SilKit_FlexrayNodeParameters SilKit_FlexrayNodeParameters;
 
diff --git a/SilKit/include/silkit/capi/InterfaceIdentifiers.h b/SilKit/include/silkit/capi/InterfaceIdentifiers.h
index 609b2870a..7490bd666 100644
--- a/SilKit/include/silkit/capi/InterfaceIdentifiers.h
+++ b/SilKit/include/silkit/capi/InterfaceIdentifiers.h
@@ -137,7 +137,7 @@ typedef struct
 #define SilKit_FlexrayWakeupEvent_VERSION 1
 #define SilKit_FlexrayControllerConfig_VERSION 1
 #define SilKit_FlexrayClusterParameters_VERSION 1
-#define SilKit_FlexrayNodeParameters_VERSION 1
+#define SilKit_FlexrayNodeParameters_VERSION 2
 #define SilKit_FlexrayHostCommand_VERSION 1
 #define SilKit_FlexrayHeader_VERSION 1
 #define SilKit_FlexrayFrame_VERSION 1
diff --git a/SilKit/include/silkit/detail/impl/HourglassConversions.hpp b/SilKit/include/silkit/detail/impl/HourglassConversions.hpp
index b242e4225..a323d02e7 100644
--- a/SilKit/include/silkit/detail/impl/HourglassConversions.hpp
+++ b/SilKit/include/silkit/detail/impl/HourglassConversions.hpp
@@ -221,6 +221,8 @@ inline void assignCxxToC(const SilKit::Services::Flexray::FlexrayNodeParameters&
     cOut.pWakeupPattern = cxxIn.pWakeupPattern;
     cOut.pdMicrotick = static_cast<SilKit_FlexrayClockPeriod>(cxxIn.pdMicrotick);
     cOut.pSamplesPerMicrotick = cxxIn.pSamplesPerMicrotick;
+    cOut.pTwoKeySlotMode = cxxIn.pTwoKeySlotMode;
+    cOut.pSecondKeySlotId = cxxIn.pSecondKeySlotId;
 }
 
 inline void assignCxxToC(const SilKit::Services::Flexray::FlexrayTxBufferConfig& cxxIn,
@@ -651,6 +653,8 @@ inline void assignCToCxx(const SilKit_FlexrayNodeParameters* cIn,
     cxxOut.pWakeupPattern = cIn->pWakeupPattern;
     cxxOut.pdMicrotick = (SilKit::Services::Flexray::FlexrayClockPeriod)cIn->pdMicrotick;
     cxxOut.pSamplesPerMicrotick = cIn->pSamplesPerMicrotick;
+    cxxOut.pTwoKeySlotMode = cIn->pTwoKeySlotMode;
+    cxxOut.pSecondKeySlotId = cIn->pSecondKeySlotId;
 }
 
 // -----------------------------------
diff --git a/SilKit/include/silkit/detail/impl/services/flexray/FlexrayController.hpp b/SilKit/include/silkit/detail/impl/services/flexray/FlexrayController.hpp
index 06150cd29..6234b21fa 100644
--- a/SilKit/include/silkit/detail/impl/services/flexray/FlexrayController.hpp
+++ b/SilKit/include/silkit/detail/impl/services/flexray/FlexrayController.hpp
@@ -567,6 +567,8 @@ void CxxToC(const SilKit::Services::Flexray::FlexrayNodeParameters& cxxFlexrayNo
     cFlexrayNodeParameters.pWakeupPattern = cxxFlexrayNodeParameters.pWakeupPattern;
     cFlexrayNodeParameters.pdMicrotick = static_cast<SilKit_FlexrayClockPeriod>(cxxFlexrayNodeParameters.pdMicrotick);
     cFlexrayNodeParameters.pSamplesPerMicrotick = cxxFlexrayNodeParameters.pSamplesPerMicrotick;
+    cFlexrayNodeParameters.pTwoKeySlotMode = cxxFlexrayNodeParameters.pTwoKeySlotMode;
+    cFlexrayNodeParameters.pSecondKeySlotId = cxxFlexrayNodeParameters.pSecondKeySlotId;
 }
 
 void CxxToC(const SilKit::Services::Flexray::FlexrayTxBufferConfig& cxxFlexrayTxBufferConfig,
diff --git a/SilKit/include/silkit/services/flexray/FlexrayDatatypes.hpp b/SilKit/include/silkit/services/flexray/FlexrayDatatypes.hpp
index 62846f3ca..e7d1c04c6 100644
--- a/SilKit/include/silkit/services/flexray/FlexrayDatatypes.hpp
+++ b/SilKit/include/silkit/services/flexray/FlexrayDatatypes.hpp
@@ -211,13 +211,6 @@ struct FlexrayNodeParameters
 
     //! Maximum permissible rate correction value (range 3-3846 MicroTicks).
     FlexrayMicroTick pRateCorrectionOut;
-
-    ////! Not used by network simulator
-    //pSecondKeySlotID
-
-    ////! Not used by network simulator
-    //pTwoKeySlotMode
-
     //! Channel used by the node to send a wakeup pattern (values FlexrayChannel::A, FlexrayChannel::B).
     FlexrayChannel pWakeupChannel;
 
@@ -238,6 +231,15 @@ struct FlexrayNodeParameters
 
     //! Number of samples per MicroTick (values 1 or 2).
     uint8_t pSamplesPerMicrotick;
+
+    // ----------------------------------------------------------------------
+    // Parameters according to B.3.2.1 (added in SIL Kit 5.0.3)
+
+    //! Second Key Slot ID of the key slot (range 0-1023, value 0 means that there is no key slot).
+    uint16_t pSecondKeySlotId;
+
+    //! Second Key slot is used for startup with a single cold start node (range 0, 1).
+    uint8_t pTwoKeySlotMode;
 };
 
 //! Transmission mode for FlexRay Tx-Buffer
@@ -537,7 +539,9 @@ inline bool operator==(const FlexrayNodeParameters& lhs, const FlexrayNodeParame
            && lhs.pOffsetCorrectionStart == rhs.pOffsetCorrectionStart
            && lhs.pRateCorrectionOut == rhs.pRateCorrectionOut && lhs.pWakeupChannel == rhs.pWakeupChannel
            && lhs.pWakeupPattern == rhs.pWakeupPattern && lhs.pdMicrotick == rhs.pdMicrotick
-           && lhs.pSamplesPerMicrotick == rhs.pSamplesPerMicrotick;
+           && lhs.pSamplesPerMicrotick == rhs.pSamplesPerMicrotick && lhs.pSecondKeySlotId == rhs.pSecondKeySlotId
+           && lhs.pTwoKeySlotMode == rhs.pTwoKeySlotMode
+        ;
 }
 
 inline bool operator==(const FlexrayTxBufferConfig& lhs, const FlexrayTxBufferConfig& rhs)
diff --git a/SilKit/source/capi/CapiFlexray.cpp b/SilKit/source/capi/CapiFlexray.cpp
index 568f34df8..644706fce 100644
--- a/SilKit/source/capi/CapiFlexray.cpp
+++ b/SilKit/source/capi/CapiFlexray.cpp
@@ -54,29 +54,40 @@ void assign(SilKit::Services::Flexray::FlexrayClusterParameters& cppClusterParam
 void assign(SilKit::Services::Flexray::FlexrayNodeParameters& cppNodeParameters,
             const SilKit_FlexrayNodeParameters* nodeParameters)
 {
-    cppNodeParameters.pAllowHaltDueToClock = nodeParameters->pAllowHaltDueToClock;
-    cppNodeParameters.pAllowPassiveToActive = nodeParameters->pAllowPassiveToActive;
-    cppNodeParameters.pChannels = (SilKit::Services::Flexray::FlexrayChannel)nodeParameters->pChannels;
-    cppNodeParameters.pClusterDriftDamping = nodeParameters->pClusterDriftDamping;
-    cppNodeParameters.pdAcceptedStartupRange = nodeParameters->pdAcceptedStartupRange;
-    cppNodeParameters.pdListenTimeout = nodeParameters->pdListenTimeout;
-    cppNodeParameters.pKeySlotId = nodeParameters->pKeySlotId;
-    cppNodeParameters.pKeySlotOnlyEnabled = nodeParameters->pKeySlotOnlyEnabled;
-    cppNodeParameters.pKeySlotUsedForStartup = nodeParameters->pKeySlotUsedForStartup;
-    cppNodeParameters.pKeySlotUsedForSync = nodeParameters->pKeySlotUsedForSync;
-    cppNodeParameters.pLatestTx = nodeParameters->pLatestTx;
-    cppNodeParameters.pMacroInitialOffsetA = nodeParameters->pMacroInitialOffsetA;
-    cppNodeParameters.pMacroInitialOffsetB = nodeParameters->pMacroInitialOffsetB;
-    cppNodeParameters.pMicroInitialOffsetA = nodeParameters->pMicroInitialOffsetA;
-    cppNodeParameters.pMicroInitialOffsetB = nodeParameters->pMicroInitialOffsetB;
-    cppNodeParameters.pMicroPerCycle = nodeParameters->pMicroPerCycle;
-    cppNodeParameters.pOffsetCorrectionOut = nodeParameters->pOffsetCorrectionOut;
-    cppNodeParameters.pOffsetCorrectionStart = nodeParameters->pOffsetCorrectionStart;
-    cppNodeParameters.pRateCorrectionOut = nodeParameters->pRateCorrectionOut;
-    cppNodeParameters.pWakeupChannel = (SilKit::Services::Flexray::FlexrayChannel)nodeParameters->pWakeupChannel;
-    cppNodeParameters.pWakeupPattern = nodeParameters->pWakeupPattern;
-    cppNodeParameters.pdMicrotick = (SilKit::Services::Flexray::FlexrayClockPeriod)nodeParameters->pdMicrotick;
-    cppNodeParameters.pSamplesPerMicrotick = nodeParameters->pSamplesPerMicrotick;
+    const auto inputVersion = SK_ID_GET_VERSION(SilKit_Struct_GetId(*nodeParameters));
+
+    if (inputVersion == 1 || inputVersion == 2)
+    {
+        cppNodeParameters.pAllowHaltDueToClock = nodeParameters->pAllowHaltDueToClock;
+        cppNodeParameters.pAllowPassiveToActive = nodeParameters->pAllowPassiveToActive;
+        cppNodeParameters.pChannels = (SilKit::Services::Flexray::FlexrayChannel)nodeParameters->pChannels;
+        cppNodeParameters.pClusterDriftDamping = nodeParameters->pClusterDriftDamping;
+        cppNodeParameters.pdAcceptedStartupRange = nodeParameters->pdAcceptedStartupRange;
+        cppNodeParameters.pdListenTimeout = nodeParameters->pdListenTimeout;
+        cppNodeParameters.pKeySlotId = nodeParameters->pKeySlotId;
+        cppNodeParameters.pKeySlotOnlyEnabled = nodeParameters->pKeySlotOnlyEnabled;
+        cppNodeParameters.pKeySlotUsedForStartup = nodeParameters->pKeySlotUsedForStartup;
+        cppNodeParameters.pKeySlotUsedForSync = nodeParameters->pKeySlotUsedForSync;
+        cppNodeParameters.pLatestTx = nodeParameters->pLatestTx;
+        cppNodeParameters.pMacroInitialOffsetA = nodeParameters->pMacroInitialOffsetA;
+        cppNodeParameters.pMacroInitialOffsetB = nodeParameters->pMacroInitialOffsetB;
+        cppNodeParameters.pMicroInitialOffsetA = nodeParameters->pMicroInitialOffsetA;
+        cppNodeParameters.pMicroInitialOffsetB = nodeParameters->pMicroInitialOffsetB;
+        cppNodeParameters.pMicroPerCycle = nodeParameters->pMicroPerCycle;
+        cppNodeParameters.pOffsetCorrectionOut = nodeParameters->pOffsetCorrectionOut;
+        cppNodeParameters.pOffsetCorrectionStart = nodeParameters->pOffsetCorrectionStart;
+        cppNodeParameters.pRateCorrectionOut = nodeParameters->pRateCorrectionOut;
+        cppNodeParameters.pWakeupChannel = (SilKit::Services::Flexray::FlexrayChannel)nodeParameters->pWakeupChannel;
+        cppNodeParameters.pWakeupPattern = nodeParameters->pWakeupPattern;
+        cppNodeParameters.pdMicrotick = (SilKit::Services::Flexray::FlexrayClockPeriod)nodeParameters->pdMicrotick;
+        cppNodeParameters.pSamplesPerMicrotick = nodeParameters->pSamplesPerMicrotick;
+    }
+
+    if (inputVersion == 2)
+    {
+        cppNodeParameters.pTwoKeySlotMode = nodeParameters->pTwoKeySlotMode;
+        cppNodeParameters.pSecondKeySlotId = nodeParameters->pSecondKeySlotId;
+    }
 }
 
 void assign(SilKit::Services::Flexray::FlexrayControllerConfig& cppConfig, const SilKit_FlexrayControllerConfig* config)
diff --git a/SilKit/source/config/ParticipantConfiguration_Full.json b/SilKit/source/config/ParticipantConfiguration_Full.json
index 877094193..6f04a8ed1 100644
--- a/SilKit/source/config/ParticipantConfiguration_Full.json
+++ b/SilKit/source/config/ParticipantConfiguration_Full.json
@@ -116,7 +116,9 @@
         "pWakeupPattern": 33,
         "pdAcceptedStartupRange": 212,
         "pdListenTimeout": 400162,
-        "pdMicrotick": "25ns"
+        "pdMicrotick": "25ns",
+        "pSecondKeySlotId": 1337,
+        "pTwoKeySlotMode": 1
       },
       "TxBufferConfigurations": [
         {
diff --git a/SilKit/source/config/ParticipantConfiguration_Full.yaml b/SilKit/source/config/ParticipantConfiguration_Full.yaml
index 3f938d2bc..4c08d28a3 100644
--- a/SilKit/source/config/ParticipantConfiguration_Full.yaml
+++ b/SilKit/source/config/ParticipantConfiguration_Full.yaml
@@ -89,11 +89,14 @@ FlexrayControllers:
     pOffsetCorrectionStart: 3632
     pRateCorrectionOut: 81
     pSamplesPerMicrotick: 2
+    pSecondKeySlotId: 1337
+    pTwoKeySlotMode: 1
     pWakeupChannel: A
     pWakeupPattern: 33
     pdAcceptedStartupRange: 212
     pdListenTimeout: 400162
     pdMicrotick: 25ns
+    
   TxBufferConfigurations:
   - channels: A
     headerCrc: 0
diff --git a/SilKit/source/config/YamlParser.hpp b/SilKit/source/config/YamlParser.hpp
index 15bc54889..9684b5a4f 100644
--- a/SilKit/source/config/YamlParser.hpp
+++ b/SilKit/source/config/YamlParser.hpp
@@ -49,7 +49,7 @@ auto Deserialize(const std::string& input) -> T
         auto root = tree.crootref();
 
         R reader{parser, root};
-        T result;
+        T result{};
         reader.Read(result);
         return result;
     }
diff --git a/SilKit/source/config/YamlReader.cpp b/SilKit/source/config/YamlReader.cpp
index f53c07f94..6a796eb39 100644
--- a/SilKit/source/config/YamlReader.cpp
+++ b/SilKit/source/config/YamlReader.cpp
@@ -97,6 +97,8 @@ void YamlReader::Read(SilKit::Services::Flexray::FlexrayNodeParameters& obj)
     ReadKeyValue(obj.pWakeupChannel, "pWakeupChannel");
     ReadKeyValue(obj.pdMicrotick, "pdMicrotick");
     ReadKeyValue(obj.pChannels, "pChannels");
+    OptionalRead(obj.pSecondKeySlotId, "pSecondKeySlotId");
+    OptionalRead(obj.pTwoKeySlotMode, "pTwoKeySlotMode");
 }
 
 void YamlReader::Read(SilKit::Services::Flexray::FlexrayTxBufferConfig& obj)
diff --git a/SilKit/source/config/YamlReader.hpp b/SilKit/source/config/YamlReader.hpp
index d513e1d04..8e74b4fea 100644
--- a/SilKit/source/config/YamlReader.hpp
+++ b/SilKit/source/config/YamlReader.hpp
@@ -57,7 +57,7 @@ class BasicYamlReader
         auto&& child = GetChildSafe(name);
         if (child.IsValid())
         {
-            T tmp;
+            T tmp{};
             child.Read(tmp);
             val = std::move(tmp); // needs a proper setter to set "has_value"
         }
diff --git a/SilKit/source/config/YamlValidator.cpp b/SilKit/source/config/YamlValidator.cpp
index be94b362b..d22b36136 100644
--- a/SilKit/source/config/YamlValidator.cpp
+++ b/SilKit/source/config/YamlValidator.cpp
@@ -246,6 +246,10 @@ const std::set<std::string> schemaPaths_v1 = {
     "/FlexRayControllers/NodeParameters/pWakeupChannel",
     "/FlexrayControllers/NodeParameters/pWakeupPattern",
     "/FlexRayControllers/NodeParameters/pWakeupPattern",
+    "/FlexrayControllers/NodeParameters/pSecondKeySlotId",
+    "/FlexRayControllers/NodeParameters/pSecondKeySlotId",
+    "/FlexrayControllers/NodeParameters/pTwoKeySlotMode",
+    "/FlexRayControllers/NodeParameters/pTwoKeySlotMode",
     "/FlexrayControllers/Replay",
     "/FlexRayControllers/Replay",
     "/FlexrayControllers/Replay/Direction",
diff --git a/SilKit/source/config/YamlWriter.cpp b/SilKit/source/config/YamlWriter.cpp
index 6e817aa84..1bcadc815 100644
--- a/SilKit/source/config/YamlWriter.cpp
+++ b/SilKit/source/config/YamlWriter.cpp
@@ -99,6 +99,7 @@ void YamlWriter::Write(const SilKit::Services::Flexray::FlexrayClusterParameters
 
 void YamlWriter::Write(const SilKit::Services::Flexray::FlexrayNodeParameters& obj)
 {
+    static const SilKit::Services::Flexray::FlexrayNodeParameters defaultNodeParams{};
     MakeMap();
     WriteKeyValue("pAllowHaltDueToClock", obj.pAllowHaltDueToClock);
     WriteKeyValue("pAllowPassiveToActive", obj.pAllowPassiveToActive);
@@ -123,6 +124,8 @@ void YamlWriter::Write(const SilKit::Services::Flexray::FlexrayNodeParameters& o
     WriteKeyValue("pWakeupChannel", obj.pWakeupChannel);
     WriteKeyValue("pdMicrotick", obj.pdMicrotick);
     WriteKeyValue("pChannels", obj.pChannels);
+    NonDefaultWrite(obj.pSecondKeySlotId, "pSecondKeySlotId", defaultNodeParams.pSecondKeySlotId);
+    NonDefaultWrite(obj.pTwoKeySlotMode, "pTwoKeySlotMode", defaultNodeParams.pTwoKeySlotMode);
 }
 
 
diff --git a/SilKit/source/services/flexray/FlexraySerdes.cpp b/SilKit/source/services/flexray/FlexraySerdes.cpp
index 5456eabdb..7a4948158 100644
--- a/SilKit/source/services/flexray/FlexraySerdes.cpp
+++ b/SilKit/source/services/flexray/FlexraySerdes.cpp
@@ -184,12 +184,22 @@ inline SilKit::Core::MessageBuffer& operator<<(SilKit::Core::MessageBuffer& buff
                                                const FlexrayControllerConfig& config)
 {
     buffer << config.clusterParams << config.nodeParams << config.bufferConfigs;
+    // Support for struct FlexrayControllerConfig version 2:
+    // ensure that the pSecondKeySlotId and pTwoKeySlotMode are also serialized after the bufferConfigs
+    // otherwise we will confuse the buffer deserialization of the bufferConfigs
+    buffer << config.nodeParams.pSecondKeySlotId << config.nodeParams.pTwoKeySlotMode;
     return buffer;
 }
 
 inline SilKit::Core::MessageBuffer& operator>>(SilKit::Core::MessageBuffer& buffer, FlexrayControllerConfig& config)
 {
     buffer >> config.clusterParams >> config.nodeParams >> config.bufferConfigs;
+    // Support for struct FlexrayControllerConfig version 2:
+    // the pSecondKeySlotId and pTwoKeySlotMode were added after the bufferConfigs
+    if (buffer.RemainingBytesLeft() > 0)
+    {
+        buffer >> config.nodeParams.pSecondKeySlotId >> config.nodeParams.pTwoKeySlotMode;
+    }
     return buffer;
 }
 
diff --git a/SilKit/source/services/flexray/Test_FlexrayController.cpp b/SilKit/source/services/flexray/Test_FlexrayController.cpp
index 625345c55..5c08474b9 100644
--- a/SilKit/source/services/flexray/Test_FlexrayController.cpp
+++ b/SilKit/source/services/flexray/Test_FlexrayController.cpp
@@ -46,7 +46,7 @@ auto GetDummyConfig() -> SilKit::Config::FlexrayController
 
 auto MakeValidClusterParams() -> FlexrayClusterParameters
 {
-    FlexrayClusterParameters clusterParams;
+    FlexrayClusterParameters clusterParams{};
     clusterParams.gColdstartAttempts = 2;
     clusterParams.gCycleCountMax = 7;
     clusterParams.gdActionPointOffset = 1;
@@ -73,7 +73,7 @@ auto MakeValidClusterParams() -> FlexrayClusterParameters
 
 auto MakeValidNodeParams() -> FlexrayNodeParameters
 {
-    FlexrayNodeParameters nodeParams;
+    FlexrayNodeParameters nodeParams{};
     nodeParams.pAllowHaltDueToClock = 0;
     nodeParams.pAllowPassiveToActive = 0;
     nodeParams.pChannels = FlexrayChannel::A;
@@ -116,7 +116,7 @@ auto MakeValidTxBufferConfig() -> FlexrayTxBufferConfig
 
 auto GetDummyConfigWithValues() -> SilKit::Config::FlexrayController
 {
-    SilKit::Config::FlexrayController dummyConfig;
+    SilKit::Config::FlexrayController dummyConfig{};
     dummyConfig.network = "testNetwork";
     dummyConfig.name = "testController";
     dummyConfig.clusterParameters = MakeValidClusterParams();