diff --git a/CHANGELOG b/CHANGELOG
index ecd71382..eaaa9046 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,7 @@
+Changes to version 1.5.0
+------------------------
+- IEC 61850 server: control models - allow delaying select response with check handler (new handler return value CONTROL_WAITING_FOR_SELECT)
+
 Changes to version 1.4.1
 ------------------------
 - MMS server: refactored connection handling; more efficient use of HandleSet
diff --git a/src/iec61850/inc/iec61850_server.h b/src/iec61850/inc/iec61850_server.h
index f34e67ea..f1d653c2 100644
--- a/src/iec61850/inc/iec61850_server.h
+++ b/src/iec61850/inc/iec61850_server.h
@@ -1146,6 +1146,7 @@ IedServer_setEditSettingGroupConfirmationHandler(IedServer self, SettingGroupCon
  */
 typedef enum {
     CONTROL_ACCEPTED = -1, /** check passed */
+    CONTROL_WAITING_FOR_SELECT = 0, /** select operation in progress - handler will be called again later */
     CONTROL_HARDWARE_FAULT = 1, /** check failed due to hardware fault */
     CONTROL_TEMPORARILY_UNAVAILABLE = 2, /** control is already selected or operated */
     CONTROL_OBJECT_ACCESS_DENIED = 3, /** check failed due to access control reason - access denied for this client or state */
diff --git a/src/iec61850/server/mms_mapping/control.c b/src/iec61850/server/mms_mapping/control.c
index cca6d5f3..e78a1894 100644
--- a/src/iec61850/server/mms_mapping/control.c
+++ b/src/iec61850/server/mms_mapping/control.c
@@ -1,7 +1,7 @@
 /*
  *  control.c
  *
- *  Copyright 2013-2019 Michael Zillgith
+ *  Copyright 2013-2020 Michael Zillgith
  *
  *  This file is part of libIEC61850.
  *
@@ -45,6 +45,7 @@
 #define STATE_PERFORM_TEST 3
 #define STATE_WAIT_FOR_EXECUTION 4
 #define STATE_OPERATE 5
+#define STATE_WAIT_FOR_SELECT 6
 
 #define PENDING_EVENT_SELECTED 1
 #define PENDING_EVENT_UNSELECTED 2
@@ -55,6 +56,8 @@
 
 static MmsValue emptyString = {MMS_STRUCTURE};
 
+static MmsValue delayedResponse = {MMS_DATA_ACCESS_ERROR, 0, {DATA_ACCESS_ERROR_NO_RESPONSE}};
+
 void
 ControlObject_sendLastApplError(ControlObject* self, MmsServerConnection connection, char* ctlVariable, int error,
         ControlAddCause addCause, MmsValue* ctlNum, MmsValue* origin, bool handlerMode);
@@ -65,10 +68,6 @@ ControlObject_sendCommandTerminationPositive(ControlObject* self);
 void
 ControlObject_sendCommandTerminationNegative(ControlObject* self);
 
-MmsValue*
-Control_readAccessControlObject(MmsMapping* self, MmsDomain* domain, char* variableIdOrig,
-        MmsServerConnection connection);
-
 static void
 unselectObject(ControlObject* self);
 
@@ -123,6 +122,65 @@ setStSeld(ControlObject* self, bool value)
     }
 }
 
+static void
+updateSboTimeoutValue(ControlObject* self)
+{
+    if (self->sboTimeout != NULL) {
+        uint32_t sboTimeoutVal = MmsValue_toInt32(self->sboTimeout);
+
+        if (DEBUG_IED_SERVER)
+            printf("IED_SERVER: set timeout for %s/%s.%s to %u\n", MmsDomain_getName(self->mmsDomain), self->lnName, self->name, sboTimeoutVal);
+
+        self->selectTimeout = sboTimeoutVal;
+    }
+    else
+        self->selectTimeout = CONFIG_CONTROL_DEFAULT_SBO_TIMEOUT;
+}
+
+static void
+selectObject(ControlObject* self, uint64_t selectTime, MmsServerConnection connection)
+{
+    if (DEBUG_IED_SERVER)
+        printf("IED_SERVER: control %s/%s.%s selected\n", MmsDomain_getName(self->mmsDomain), self->lnName, self->name);
+
+    updateSboTimeoutValue(self);
+
+    self->selectTime = selectTime;
+    self->mmsConnection = connection;
+    setStSeld(self, true);
+    setState(self, STATE_READY);
+}
+
+static void
+unselectObject(ControlObject* self)
+{
+    setState(self, STATE_UNSELECTED);
+
+    setStSeld(self, false);
+
+    if (DEBUG_IED_SERVER)
+        printf("IED_SERVER: control %s/%s.%s unselected\n", MmsDomain_getName(self->mmsDomain), self->lnName, self->name);
+}
+
+static void
+checkSelectTimeout(ControlObject* self, uint64_t currentTime)
+{
+    if ((self->ctlModel == 2) || (self->ctlModel == 4)) {
+
+        if (getState(self) == STATE_READY) {
+            if (self->selectTimeout > 0) {
+                if (currentTime > (self->selectTime + self->selectTimeout)) {
+                    if (DEBUG_IED_SERVER)
+                        printf("IED_SERVER: select-timeout (timeout-val = %i) for control %s/%s.%s\n",
+                                self->selectTimeout, MmsDomain_getName(self->mmsDomain), self->lnName, self->name);
+
+                    unselectObject(self);
+                }
+            }
+        }
+    }
+}
+
 static void
 setOpRcvd(ControlObject* self, bool value)
 {
@@ -159,7 +217,6 @@ setOpOk(ControlObject* self, bool value, uint64_t currentTimeInMs)
                 /* TODO update time quality */
             }
 
-
             self->pendingEvents |= PENDING_EVENT_OP_OK_TRUE;
         }
         else
@@ -171,21 +228,6 @@ setOpOk(ControlObject* self, bool value, uint64_t currentTimeInMs)
     }
 }
 
-static void
-updateSboTimeoutValue(ControlObject* self)
-{
-    if (self->sboTimeout != NULL) {
-        uint32_t sboTimeoutVal = MmsValue_toInt32(self->sboTimeout);
-
-        if (DEBUG_IED_SERVER)
-            printf("IED_SERVER: set timeout for %s/%s.%s to %u\n", MmsDomain_getName(self->mmsDomain), self->lnName, self->name, sboTimeoutVal);
-
-        self->selectTimeout = sboTimeoutVal;
-    }
-    else
-        self->selectTimeout = CONFIG_CONTROL_DEFAULT_SBO_TIMEOUT;
-}
-
 static bool
 isSboClassOperateOnce(ControlObject* self)
 {
@@ -280,6 +322,74 @@ executeStateMachine:
 
     switch (state) {
 
+    case STATE_WAIT_FOR_SELECT:
+    {
+        self->isSelect = 1;
+
+        CheckHandlerResult checkHandlerResult = self->checkHandler((ControlAction) self, self->checkHandlerParameter, NULL, false, false);
+
+        self->isSelect = 0;
+
+        if (checkHandlerResult != CONTROL_WAITING_FOR_SELECT) {
+
+            if (self->ctlModel == 2) {
+                LinkedList values = LinkedList_create();
+
+                if (checkHandlerResult == CONTROL_ACCEPTED) {
+                    LinkedList_add(values, self->sbo);
+
+                    selectObject(self, Hal_getTimeInMs(), self->mmsConnection);
+                }
+                else {
+                    LinkedList_add(values, &emptyString);
+
+                    setState(self, STATE_UNSELECTED);
+                }
+
+                MmsServerConnection_sendReadResponse(self->mmsConnection, self->operateInvokeId, values, false);
+
+                LinkedList_destroyStatic(values);
+            }
+            else if (self->ctlModel == 4) {
+                if (checkHandlerResult == CONTROL_ACCEPTED) {
+
+                    selectObject(self, Hal_getTimeInMs(), self->mmsConnection);
+
+                    if (self->ctlNumSt)
+                        MmsValue_update(self->ctlNumSt, self->ctlNum);
+
+                    if (self->originSt)
+                        MmsValue_update(self->originSt, self->origin);
+
+                    MmsServerConnection_sendWriteResponse(self->mmsConnection, self->operateInvokeId, DATA_ACCESS_ERROR_SUCCESS, false);
+
+                    if (DEBUG_IED_SERVER)
+                        printf("IED_SERVER: SBOw - selected successful\n");
+                }
+                else {
+
+                    setState(self, STATE_UNSELECTED);
+
+                    ControlObject_sendLastApplError(self, self->mmsConnection, "SBOw", 0,
+                            ADD_CAUSE_SELECT_FAILED, self->ctlNum, self->origin, false);
+
+                    MmsServerConnection_sendWriteResponse(self->mmsConnection, self->operateInvokeId, (MmsDataAccessError) checkHandlerResult, false);
+
+                    if (DEBUG_IED_SERVER)
+                        printf("IED_SERVER: SBOw - select rejected by application!\n");
+                }
+            }
+            else {
+                /* ERROR: invalid internal state! */
+                setState(self, STATE_WAIT_FOR_SELECT);
+            }
+
+        }
+
+    }
+    break;
+
+
     case STATE_WAIT_FOR_ACTIVATION_TIME:
     case STATE_WAIT_FOR_EXECUTION:
     {
@@ -681,50 +791,6 @@ ControlObject_getMmsValue(ControlObject* self)
     return self->mmsValue;
 }
 
-static void
-selectObject(ControlObject* self, uint64_t selectTime, MmsServerConnection connection)
-{
-    if (DEBUG_IED_SERVER)
-        printf("IED_SERVER: control %s/%s.%s selected\n", MmsDomain_getName(self->mmsDomain), self->lnName, self->name);
-
-    updateSboTimeoutValue(self);
-
-    self->selectTime = selectTime;
-    self->mmsConnection = connection;
-    setStSeld(self, true);
-    setState(self, STATE_READY);
-}
-
-static void
-unselectObject(ControlObject* self)
-{
-    setState(self, STATE_UNSELECTED);
-
-    setStSeld(self, false);
-
-    if (DEBUG_IED_SERVER)
-        printf("IED_SERVER: control %s/%s.%s unselected\n", MmsDomain_getName(self->mmsDomain), self->lnName, self->name);
-}
-
-static void
-checkSelectTimeout(ControlObject* self, uint64_t currentTime)
-{
-    if ((self->ctlModel == 2) || (self->ctlModel == 4)) {
-
-        if (getState(self) == STATE_READY) {
-            if (self->selectTimeout > 0) {
-                if (currentTime > (self->selectTime + self->selectTimeout)) {
-                    if (DEBUG_IED_SERVER)
-                        printf("IED_SERVER: select-timeout (timeout-val = %i) for control %s/%s.%s\n",
-                                self->selectTimeout, MmsDomain_getName(self->mmsDomain), self->lnName, self->name);
-
-                    unselectObject(self);
-                }
-            }
-        }
-    }
-}
-
 bool
 ControlObject_unselect(ControlObject* self, MmsServerConnection connection)
 {
@@ -1181,7 +1247,7 @@ doesElementEquals(char* element, char* name)
 
 MmsValue*
 Control_readAccessControlObject(MmsMapping* self, MmsDomain* domain, char* variableIdOrig,
-        MmsServerConnection connection)
+        MmsServerConnection connection, bool isDirectAccess)
 {
     MmsValue* value = NULL;
 
@@ -1259,28 +1325,36 @@ Control_readAccessControlObject(MmsMapping* self, MmsDomain* domain, char* varia
 
                     value = &emptyString;
 
-                    checkSelectTimeout(controlObject, currentTime);
+                    if (isDirectAccess == true) {
+                        checkSelectTimeout(controlObject, currentTime);
 
-                    if (getState(controlObject) == STATE_UNSELECTED) {
-                        CheckHandlerResult checkResult = CONTROL_ACCEPTED;
+                        if (getState(controlObject) == STATE_UNSELECTED) {
+                            CheckHandlerResult checkResult = CONTROL_ACCEPTED;
 
-                        /* opRcvd must not be set here! */
+                            /* opRcvd must not be set here! */
 
-                        controlObject->addCauseValue = ADD_CAUSE_UNKNOWN;
+                            controlObject->addCauseValue = ADD_CAUSE_UNKNOWN;
 
-                        if (controlObject->checkHandler != NULL) { /* perform operative tests */
+                            if (controlObject->checkHandler != NULL) { /* perform operative tests */
 
-                            controlObject->isSelect = 1;
+                                controlObject->isSelect = 1;
 
-                            checkResult = controlObject->checkHandler((ControlAction) controlObject,
-                                    controlObject->checkHandlerParameter, NULL, false, false);
+                                checkResult = controlObject->checkHandler((ControlAction) controlObject,
+                                        controlObject->checkHandlerParameter, NULL, false, false);
 
-                            controlObject->isSelect = 0;
-                        }
+                                controlObject->isSelect = 0;
+                            }
 
-                        if (checkResult == CONTROL_ACCEPTED) {
-                            selectObject(controlObject, currentTime, connection);
-                            value = controlObject->sbo;
+                            if (checkResult == CONTROL_ACCEPTED) {
+                                selectObject(controlObject, currentTime, connection);
+                                value = controlObject->sbo;
+                            }
+                            else if (checkResult == CONTROL_WAITING_FOR_SELECT) {
+                                controlObject->mmsConnection = connection;
+                                controlObject->operateInvokeId = MmsServerConnection_getLastInvokeId(connection);
+                                setState(controlObject, STATE_WAIT_FOR_SELECT);
+                                value = &delayedResponse;
+                            }
                         }
                     }
 
@@ -1398,11 +1472,9 @@ Control_writeAccessControlObject(MmsMapping* self, MmsDomain* domain, char* vari
             varName = NULL;
     }
 
-
     if (DEBUG_IED_SERVER)
         printf("IED_SERVER: write access control: objectName: (%s) varName: (%s)\n", objectName, varName);
 
-
     if (varName == NULL) {
         indication = DATA_ACCESS_ERROR_OBJECT_ACCESS_DENIED;
         goto free_and_return;
@@ -1489,6 +1561,18 @@ Control_writeAccessControlObject(MmsMapping* self, MmsDomain* domain, char* vari
                         if (DEBUG_IED_SERVER)
                             printf("IED_SERVER: SBOw - selected successful\n");
                     }
+                    else if (checkResult == CONTROL_WAITING_FOR_SELECT) {
+                        controlObject->mmsConnection = connection;
+                        controlObject->operateInvokeId = MmsServerConnection_getLastInvokeId(connection);
+
+                        MmsValue_update(controlObject->ctlVal, ctlVal);
+                        MmsValue_update(controlObject->ctlNum, ctlNum);
+                        MmsValue_update(controlObject->origin, origin);
+
+                        setState(controlObject, STATE_WAIT_FOR_SELECT);
+
+                        indication = DATA_ACCESS_ERROR_NO_RESPONSE;
+                    }
                     else {
                         indication = (MmsDataAccessError) checkResult;
 
diff --git a/src/iec61850/server/mms_mapping/mms_mapping.c b/src/iec61850/server/mms_mapping/mms_mapping.c
index a9f75615..5a097453 100644
--- a/src/iec61850/server/mms_mapping/mms_mapping.c
+++ b/src/iec61850/server/mms_mapping/mms_mapping.c
@@ -71,7 +71,7 @@ typedef struct
 #if (CONFIG_IEC61850_CONTROL_SERVICE == 1)
 MmsValue*
 Control_readAccessControlObject(MmsMapping* self, MmsDomain* domain, char* variableIdOrig,
-        MmsServerConnection connection);
+        MmsServerConnection connection, bool isDirectAccess);
 #endif
 
 void /* Create PHYCOMADDR ACSI type instance */
@@ -2248,7 +2248,7 @@ readAccessGooseControlBlock(MmsMapping* self, MmsDomain* domain, char* variableI
 
 
 static MmsValue*
-mmsReadHandler(void* parameter, MmsDomain* domain, char* variableId, MmsServerConnection connection)
+mmsReadHandler(void* parameter, MmsDomain* domain, char* variableId, MmsServerConnection connection, bool isDirectAccess)
 {
     MmsMapping* self = (MmsMapping*) parameter;
 
@@ -2267,7 +2267,7 @@ mmsReadHandler(void* parameter, MmsDomain* domain, char* variableId, MmsServerCo
 #if (CONFIG_IEC61850_CONTROL_SERVICE == 1)
     /* Controllable objects - CO */
     if (isControllable(separator)) {
-        retValue = Control_readAccessControlObject(self, domain, variableId, connection);
+        retValue = Control_readAccessControlObject(self, domain, variableId, connection, isDirectAccess);
         goto exit_function;
     }
 #endif
@@ -2362,7 +2362,6 @@ mmsReadHandler(void* parameter, MmsDomain* domain, char* variableId, MmsServerCo
 
     /* handle read access to other objects */
 
-
 exit_function:
     return retValue;
 }
@@ -2436,7 +2435,7 @@ mmsConnectionHandler(void* parameter, MmsServerConnection connection, MmsServerE
 }
 
 static MmsDataAccessError
-mmsReadAccessHandler (void* parameter, MmsDomain* domain, char* variableId, MmsServerConnection connection)
+mmsReadAccessHandler (void* parameter, MmsDomain* domain, char* variableId, MmsServerConnection connection, bool isDirectAccess)
 {
     MmsMapping* self = (MmsMapping*) parameter;
 
diff --git a/src/mms/inc_private/mms_server_connection.h b/src/mms/inc_private/mms_server_connection.h
index 15d4c1a9..cb4e8fb8 100644
--- a/src/mms/inc_private/mms_server_connection.h
+++ b/src/mms/inc_private/mms_server_connection.h
@@ -99,6 +99,9 @@ LIB61850_INTERNAL void
 MmsServerConnection_sendWriteResponse(MmsServerConnection self, uint32_t invokeId, MmsDataAccessError indication,
         bool handlerMode);
 
+LIB61850_INTERNAL void
+MmsServerConnection_sendReadResponse(MmsServerConnection self, uint32_t invokeId, LinkedList values,
+        bool handlerMode);
 
 LIB61850_INTERNAL uint32_t
 MmsServerConnection_getLastInvokeId(MmsServerConnection self);
diff --git a/src/mms/inc_private/mms_server_internal.h b/src/mms/inc_private/mms_server_internal.h
index 23430d4d..dfc0dbd7 100644
--- a/src/mms/inc_private/mms_server_internal.h
+++ b/src/mms/inc_private/mms_server_internal.h
@@ -391,8 +391,13 @@ LIB61850_INTERNAL MmsDataAccessError
 mmsServer_setValue(MmsServer self, MmsDomain* domain, char* itemId, MmsValue* value,
         MmsServerConnection connection);
 
+/**
+ * \brief Get the current value of a variable in the server data model
+ *
+ * \param isDirectAccess the access is result of a direct single read access to the variable and no part of broader read request
+ */
 LIB61850_INTERNAL MmsValue*
-mmsServer_getValue(MmsServer self, MmsDomain* domain, char* itemId, MmsServerConnection connection);
+mmsServer_getValue(MmsServer self, MmsDomain* domain, char* itemId, MmsServerConnection connection, bool isDirectAccess);
 
 LIB61850_INTERNAL void
 mmsServer_createMmsWriteResponse(MmsServerConnection connection,
diff --git a/src/mms/inc_private/mms_server_libinternal.h b/src/mms/inc_private/mms_server_libinternal.h
index b516513a..b516a2d7 100644
--- a/src/mms/inc_private/mms_server_libinternal.h
+++ b/src/mms/inc_private/mms_server_libinternal.h
@@ -28,10 +28,10 @@
 #include "mms_device_model.h"
 
 typedef MmsValue* (*MmsReadVariableHandler)(void* parameter, MmsDomain* domain,
-        char* variableId, MmsServerConnection connection);
+        char* variableId, MmsServerConnection connection, bool isDirectAccess);
 
 typedef MmsDataAccessError (*MmsReadAccessHandler) (void* parameter, MmsDomain* domain,
-        char* variableId, MmsServerConnection connection);
+        char* variableId, MmsServerConnection connection, bool isDirectAccess);
 
 typedef MmsDataAccessError (*MmsWriteVariableHandler)(void* parameter,
         MmsDomain* domain, char* variableId, MmsValue* value,
diff --git a/src/mms/iso_mms/server/mms_read_service.c b/src/mms/iso_mms/server/mms_read_service.c
index dba52d1b..2f38a854 100644
--- a/src/mms/iso_mms/server/mms_read_service.c
+++ b/src/mms/iso_mms/server/mms_read_service.c
@@ -51,7 +51,7 @@ addNamedVariableValue(MmsVariableSpecification* namedVariable, MmsServerConnecti
 
     if (namedVariable->type == MMS_STRUCTURE) {
 
-        value = mmsServer_getValue(connection->server, domain, itemId, connection);
+        value = mmsServer_getValue(connection->server, domain, itemId, connection, false);
 
         if (value != NULL)
             goto exit_function;
@@ -86,7 +86,7 @@ addNamedVariableValue(MmsVariableSpecification* namedVariable, MmsServerConnecti
         }
     }
     else {
-        value = mmsServer_getValue(connection->server, domain, itemId, connection);
+        value = mmsServer_getValue(connection->server, domain, itemId, connection, false);
     }
 
 exit_function:
@@ -183,7 +183,6 @@ getComponent(MmsServerConnection connection, MmsDomain* domain, AlternateAccess_
                             strcat(variableName, "$");
                             strncat(variableName, (const char*) component.buf, component.size);
 
-
                             if (alternateAccess->list.array[0]->choice.unnamed->choice.selectAlternateAccess.alternateAccess
                                     != NULL) {
                                 retValue =
@@ -193,7 +192,7 @@ getComponent(MmsServerConnection connection, MmsDomain* domain, AlternateAccess_
                                                 variableName);
                             }
                             else {
-                                retValue = mmsServer_getValue(connection->server, domain, variableName, connection);
+                                retValue = mmsServer_getValue(connection->server, domain, variableName, connection, false);
                             }
                         }
                     }
@@ -275,7 +274,7 @@ alternateArrayAccess(MmsServerConnection connection,
 
 		int index = lowIndex;
 
-		MmsValue* arrayValue = mmsServer_getValue(connection->server, domain, itemId, connection);
+		MmsValue* arrayValue = mmsServer_getValue(connection->server, domain, itemId, connection, false);
 
 		if (arrayValue != NULL) {
 
@@ -335,7 +334,7 @@ alternateArrayAccess(MmsServerConnection connection,
 
 static void
 addNamedVariableToResultList(MmsVariableSpecification* namedVariable, MmsDomain* domain, char* nameIdStr,
-		LinkedList /*<MmsValue>*/ values, MmsServerConnection connection, AlternateAccess_t* alternateAccess)
+		LinkedList /*<MmsValue>*/ values, MmsServerConnection connection, AlternateAccess_t* alternateAccess, bool isAccessToSingleVariable)
 {
     if (namedVariable != NULL) {
 
@@ -345,7 +344,7 @@ addNamedVariableToResultList(MmsVariableSpecification* namedVariable, MmsDomain*
 
         if (namedVariable->type == MMS_STRUCTURE) {
 
-            MmsValue* value = mmsServer_getValue(connection->server, domain, nameIdStr, connection);
+            MmsValue* value = mmsServer_getValue(connection->server, domain, nameIdStr, connection, isAccessToSingleVariable);
 
             if (alternateAccess != NULL) {
 
@@ -379,7 +378,7 @@ addNamedVariableToResultList(MmsVariableSpecification* namedVariable, MmsDomain*
                         nameIdStr, values, namedVariable);
             }
             else { /* return complete array */
-                MmsValue* value = mmsServer_getValue(connection->server, domain, nameIdStr, connection);
+                MmsValue* value = mmsServer_getValue(connection->server, domain, nameIdStr, connection, isAccessToSingleVariable);
                 appendValueToResultList(value, values);
             }
         }
@@ -389,7 +388,7 @@ addNamedVariableToResultList(MmsVariableSpecification* namedVariable, MmsDomain*
                 appendErrorToResultList(values, DATA_ACCESS_ERROR_OBJECT_NONE_EXISTENT);
             }
             else {
-                MmsValue* value = mmsServer_getValue(connection->server, domain, nameIdStr, connection);
+                MmsValue* value = mmsServer_getValue(connection->server, domain, nameIdStr, connection, isAccessToSingleVariable);
 
                 if (value == NULL) {
                     if (DEBUG_MMS_SERVER)
@@ -641,7 +640,7 @@ handleReadListOfVariablesRequest(
                         appendErrorToResultList(values, DATA_ACCESS_ERROR_OBJECT_NONE_EXISTENT);
                     else
                         addNamedVariableToResultList(namedVariable, domain, nameIdStr,
-                            values, connection, alternateAccess);
+                            values, connection, alternateAccess, variableCount == 1);
 				}
 			}
 #if (CONFIG_MMS_SUPPORT_VMD_SCOPE_NAMED_VARIABLES == 1)
@@ -678,7 +677,28 @@ handleReadListOfVariablesRequest(
 		}
 	}
 
-	encodeReadResponse(connection, invokeId, response, values, NULL);
+	bool sendResponse = true;
+
+	LinkedList valueElement = LinkedList_getNext(values);
+
+	while (valueElement) {
+
+	    MmsValue* value = (MmsValue*) LinkedList_getData(valueElement);
+
+	    if (value) {
+	        if (MmsValue_getType(value) == MMS_DATA_ACCESS_ERROR) {
+	            if (MmsValue_getDataAccessError(value) == DATA_ACCESS_ERROR_NO_RESPONSE) {
+	                sendResponse = false;
+	                break;
+	            }
+	        }
+	    }
+
+	    valueElement = LinkedList_getNext(valueElement);
+	}
+
+	if (sendResponse)
+	    encodeReadResponse(connection, invokeId, response, values, NULL);
 
 exit:
 
@@ -689,7 +709,7 @@ exit:
 
 static void
 createNamedVariableListResponse(MmsServerConnection connection, MmsNamedVariableList namedList,
-		int invokeId, ByteBuffer* response, ReadRequest_t* read, VarAccessSpec* accessSpec)
+		int invokeId, ByteBuffer* response, bool isSpecWithResult, VarAccessSpec* accessSpec)
 {
 
 	LinkedList /*<MmsValue>*/ values = LinkedList_create();
@@ -712,12 +732,12 @@ createNamedVariableListResponse(MmsServerConnection connection, MmsNamedVariable
 				variableName);
 
 		addNamedVariableToResultList(namedVariable, variableDomain, variableName,
-								values, connection, NULL);
+								values, connection, NULL, false);
 
 		variable = LinkedList_getNext(variable);
 	}
 
-	if (isSpecWithResult(read)) /* add specification to result */
+	if (isSpecWithResult) /* add specification to result */
 		encodeReadResponse(connection, invokeId, response, values, accessSpec);
 	else
 		encodeReadResponse(connection, invokeId, response, values, NULL);
@@ -769,7 +789,7 @@ handleReadNamedVariableListRequest(
 			MmsNamedVariableList namedList = MmsDomain_getNamedVariableList(domain, nameIdStr);
 
 			if (namedList != NULL) {
-				createNamedVariableListResponse(connection, namedList, invokeId, response, read,
+				createNamedVariableListResponse(connection, namedList, invokeId, response, isSpecWithResult(read),
 						&accessSpec);
 			}
 			else {
@@ -798,7 +818,7 @@ handleReadNamedVariableListRequest(
             accessSpec.domainId = NULL;
             accessSpec.itemId = listName;
 
-            createNamedVariableListResponse(connection, namedList, invokeId, response, read, &accessSpec);
+            createNamedVariableListResponse(connection, namedList, invokeId, response, isSpecWithResult(read), &accessSpec);
         }
 	}
 #if (MMS_DYNAMIC_DATA_SETS == 1)
@@ -822,7 +842,7 @@ handleReadNamedVariableListRequest(
             accessSpec.domainId = NULL;
             accessSpec.itemId = listName;
 
-			createNamedVariableListResponse(connection, namedList, invokeId, response, read, &accessSpec);
+			createNamedVariableListResponse(connection, namedList, invokeId, response, isSpecWithResult(read), &accessSpec);
 		}
 	}
 #endif /* (MMS_DYNAMIC_DATA_SETS == 1) */
@@ -868,3 +888,23 @@ exit_function:
 	asn_DEF_MmsPdu.free_struct(&asn_DEF_MmsPdu, mmsPdu, 0);
 }
 
+void
+MmsServerConnection_sendReadResponse(MmsServerConnection self, uint32_t invokeId, LinkedList values, bool handlerMode)
+{
+    if (handlerMode == false)
+        IsoConnection_lock(self->isoConnection);
+
+    ByteBuffer* response = MmsServer_reserveTransmitBuffer(self->server);
+
+    ByteBuffer_setSize(response, 0);
+
+    encodeReadResponse(self, invokeId, response, values, NULL);
+
+    IsoConnection_sendMessage(self->isoConnection, response);
+
+    MmsServer_releaseTransmitBuffer(self->server);
+
+    if (handlerMode == false)
+        IsoConnection_unlock(self->isoConnection);
+}
+
diff --git a/src/mms/iso_mms/server/mms_server.c b/src/mms/iso_mms/server/mms_server.c
index b5af1737..16df4506 100644
--- a/src/mms/iso_mms/server/mms_server.c
+++ b/src/mms/iso_mms/server/mms_server.c
@@ -367,14 +367,14 @@ mmsServer_setValue(MmsServer self, MmsDomain* domain, char* itemId, MmsValue* va
 
 
 MmsValue*
-mmsServer_getValue(MmsServer self, MmsDomain* domain, char* itemId, MmsServerConnection connection)
+mmsServer_getValue(MmsServer self, MmsDomain* domain, char* itemId, MmsServerConnection connection, bool isDirectAccess)
 {
     MmsValue* value = NULL;
 
     if (self->readAccessHandler != NULL) {
         MmsDataAccessError accessError =
                 self->readAccessHandler(self->readAccessHandlerParameter, (domain == (MmsDomain*) self->device) ? NULL : domain,
-                        itemId, connection);
+                        itemId, connection, isDirectAccess);
 
         if (accessError != DATA_ACCESS_ERROR_SUCCESS) {
             value = MmsValue_newDataAccessError(accessError);
@@ -388,7 +388,7 @@ mmsServer_getValue(MmsServer self, MmsDomain* domain, char* itemId, MmsServerCon
     if (value == NULL)
         if (self->readHandler != NULL)
             value = self->readHandler(self->readHandlerParameter, (domain == (MmsDomain*) self->device) ? NULL : domain,
-                    itemId, connection);
+                    itemId, connection, isDirectAccess);
 
 exit_function:
     return value;
diff --git a/src/mms/iso_mms/server/mms_write_service.c b/src/mms/iso_mms/server/mms_write_service.c
index 08afbc1c..dd8a7cd3 100644
--- a/src/mms/iso_mms/server/mms_write_service.c
+++ b/src/mms/iso_mms/server/mms_write_service.c
@@ -359,7 +359,7 @@ createWriteNamedVariableListResponse(
         MmsDomain* variableDomain = MmsNamedVariableListEntry_getDomain(variableListEntry);
         char* variableName = MmsNamedVariableListEntry_getVariableName(variableListEntry);
 
-        MmsValue* oldValue = mmsServer_getValue(connection->server, variableDomain, variableName, connection);
+        MmsValue* oldValue = mmsServer_getValue(connection->server, variableDomain, variableName, connection, false);
 
         Data_t* dataElement = writeRequest->listOfData.list.array[i];