diff --git a/bacnet-stack/demo/object/ao.c b/bacnet-stack/demo/object/ao.c
index ca645f13..c015af54 100644
--- a/bacnet-stack/demo/object/ao.c
+++ b/bacnet-stack/demo/object/ao.c
@@ -35,6 +35,7 @@
 #include "config.h"     /* the custom stuff */
 #include "wp.h"
 #include "ao.h"
+#include "handlers.h"
 
 #define MAX_ANALOG_OUTPUTS 4
 
@@ -436,7 +437,7 @@ bool Analog_Output_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_VALUE_OUT_OF_RANGE;
                 }
-            } else if (value.tag == BACNET_APPLICATION_TAG_NULL) {
+            } else if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_NULL, error_class, error_code) == true) {
                 level = AO_LEVEL_NULL;
                 object_index =
                     Analog_Output_Instance_To_Index(wp_data->object_instance);
@@ -447,21 +448,14 @@ bool Analog_Output_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_VALUE_OUT_OF_RANGE;
                 }
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         case PROP_OUT_OF_SERVICE:
-            if (value.tag == BACNET_APPLICATION_TAG_BOOLEAN) {
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_BOOLEAN, error_class, error_code)) == true) {
                 object_index =
                     Analog_Output_Instance_To_Index(wp_data->object_instance);
                 Analog_Output_Out_Of_Service[object_index] =
                     value.type.Boolean;
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         default:
diff --git a/bacnet-stack/demo/object/av.c b/bacnet-stack/demo/object/av.c
index 87597ce9..fff28a71 100644
--- a/bacnet-stack/demo/object/av.c
+++ b/bacnet-stack/demo/object/av.c
@@ -35,6 +35,7 @@
 #include "config.h"     /* the custom stuff */
 #include "wp.h"
 #include "av.h"
+#include "handlers.h"
 
 /* we choose to have a NULL level in our system represented by */
 /* a particular value.  When the priorities are not in use, they */
@@ -397,7 +398,7 @@ bool Analog_Value_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_VALUE_OUT_OF_RANGE;
                 }
-            } else if (value.tag == BACNET_APPLICATION_TAG_NULL) {
+            } else if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_NULL, error_class, error_code) == true) {
                 level = ANALOG_LEVEL_NULL;
                 object_index =
                     Analog_Value_Instance_To_Index(wp_data->object_instance);
@@ -416,20 +417,13 @@ bool Analog_Value_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_VALUE_OUT_OF_RANGE;
                 }
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         case PROP_OUT_OF_SERVICE:
-            if (value.tag == BACNET_APPLICATION_TAG_BOOLEAN) {
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_BOOLEAN, error_class, error_code)) == true) {
                 object_index =
                     Analog_Value_Instance_To_Index(wp_data->object_instance);
                 Analog_Value_Out_Of_Service[object_index] = value.type.Boolean;
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         default:
diff --git a/bacnet-stack/demo/object/bacfile.c b/bacnet-stack/demo/object/bacfile.c
index 980e35fc..ad8582c1 100644
--- a/bacnet-stack/demo/object/bacfile.c
+++ b/bacnet-stack/demo/object/bacfile.c
@@ -300,27 +300,21 @@ bool bacfile_write_property(
                property shall be logical TRUE only if no changes have been
                made to the file data by internal processes or through File
                Access Services since the last time the object was archived. */
-            if (value.tag == BACNET_APPLICATION_TAG_BOOLEAN) {
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_BOOLEAN, error_class, error_code)) == true) {
                 if (value.type.Boolean) {
                     /* FIXME: do something to wp_data->object_instance */
                 } else {
                     /* FIXME: do something to wp_data->object_instance */
                 }
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         case PROP_FILE_SIZE:
             /* If the file size can be changed by writing to the file,
                and File_Access_Method is STREAM_ACCESS, then this property
                shall be writable. */
-            if (value.tag == BACNET_APPLICATION_TAG_UNSIGNED_INT) {
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_UNSIGNED_INT, error_class, error_code)) == true) {
                 /* FIXME: do something with value.type.Unsigned
                    to wp_data->object_instance */
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         default:
diff --git a/bacnet-stack/demo/object/bi.c b/bacnet-stack/demo/object/bi.c
index 9d376550..63815357 100644
--- a/bacnet-stack/demo/object/bi.c
+++ b/bacnet-stack/demo/object/bi.c
@@ -34,6 +34,7 @@
 #include "wp.h"
 #include "cov.h"
 #include "config.h"     /* the custom stuff */
+#include "handlers.h"
 
 #define MAX_BINARY_INPUTS 5
 
@@ -394,7 +395,7 @@ bool Binary_Input_Write_Property(
     /* FIXME: len == 0: unable to decode? */
     switch (wp_data->object_property) {
         case PROP_PRESENT_VALUE:
-            if (value.tag == BACNET_APPLICATION_TAG_ENUMERATED) {
+            if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_ENUMERATED, error_class, error_code) == true) {
                 if (value.type.Enumerated <= MAX_BINARY_PV) {
                     Binary_Input_Present_Value_Set(wp_data->object_instance,
                         (BACNET_BINARY_PV) value.type.Enumerated);
@@ -403,19 +404,12 @@ bool Binary_Input_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_VALUE_OUT_OF_RANGE;
                 }
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         case PROP_OUT_OF_SERVICE:
-            if (value.tag == BACNET_APPLICATION_TAG_BOOLEAN) {
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_BOOLEAN, error_class, error_code)) == true) {
                 Binary_Input_Out_Of_Service_Set(wp_data->object_instance,
                     value.type.Boolean);
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         default:
diff --git a/bacnet-stack/demo/object/bo.c b/bacnet-stack/demo/object/bo.c
index 33336809..89f0f84a 100644
--- a/bacnet-stack/demo/object/bo.c
+++ b/bacnet-stack/demo/object/bo.c
@@ -34,6 +34,7 @@
 #include "bacapp.h"
 #include "config.h"     /* the custom stuff */
 #include "wp.h"
+#include "handlers.h"
 
 #define MAX_BINARY_OUTPUTS 6
 
@@ -392,7 +393,7 @@ bool Binary_Output_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_VALUE_OUT_OF_RANGE;
                 }
-            } else if (value.tag == BACNET_APPLICATION_TAG_NULL) {
+            } else if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_NULL, error_class, error_code) == true) {
                 level = BINARY_NULL;
                 object_index =
                     Binary_Output_Instance_To_Index(wp_data->object_instance);
@@ -411,21 +412,14 @@ bool Binary_Output_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_VALUE_OUT_OF_RANGE;
                 }
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         case PROP_OUT_OF_SERVICE:
-            if (value.tag == BACNET_APPLICATION_TAG_BOOLEAN) {
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_BOOLEAN, error_class, error_code)) == true) {
                 object_index =
                     Binary_Output_Instance_To_Index(wp_data->object_instance);
                 Binary_Output_Out_Of_Service[object_index] =
                     value.type.Boolean;
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         default:
diff --git a/bacnet-stack/demo/object/bv.c b/bacnet-stack/demo/object/bv.c
index 8b48b8f8..dcb35558 100644
--- a/bacnet-stack/demo/object/bv.c
+++ b/bacnet-stack/demo/object/bv.c
@@ -34,6 +34,7 @@
 #include "bacapp.h"
 #include "config.h"     /* the custom stuff */
 #include "wp.h"
+#include "handlers.h"
 
 #define MAX_BINARY_VALUES 2
 
@@ -373,7 +374,7 @@ bool Binary_Value_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_VALUE_OUT_OF_RANGE;
                 }
-            } else if (value.tag == BACNET_APPLICATION_TAG_NULL) {
+            } else if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_NULL, error_class, error_code) == true) {
                 level = BINARY_NULL;
                 object_index =
                     Binary_Value_Instance_To_Index(wp_data->object_instance);
@@ -392,20 +393,12 @@ bool Binary_Value_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_VALUE_OUT_OF_RANGE;
                 }
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         case PROP_OUT_OF_SERVICE:
-            if (value.tag == BACNET_APPLICATION_TAG_BOOLEAN) {
-                object_index =
-                    Binary_Value_Instance_To_Index(wp_data->object_instance);
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_BOOLEAN, error_class, error_code)) == true) {
+                object_index = Binary_Value_Instance_To_Index(wp_data->object_instance);
                 Binary_Value_Out_Of_Service[object_index] = value.type.Boolean;
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         default:
diff --git a/bacnet-stack/demo/object/lo.c b/bacnet-stack/demo/object/lo.c
index f7cb18ed..73cbd7ab 100644
--- a/bacnet-stack/demo/object/lo.c
+++ b/bacnet-stack/demo/object/lo.c
@@ -39,6 +39,7 @@
 #include "bacapp.h"
 #include "config.h"     /* the custom stuff */
 #include "wp.h"
+#include "handlers.h"
 
 #define MAX_LIGHTING_OUTPUTS 5
 
@@ -155,7 +156,7 @@ int Lighting_Output_Decode_Lighting_Command(
         apdu_len += len;
         len =
             decode_enumerated(&apdu[apdu_len], len_value_type,
-            &data->operation);
+            (uint32_t *)&data->operation);
         apdu_len += len;
         /* Tag 1: level - OPTIONAL */
         if (decode_is_context_tag(&apdu[apdu_len], 1)) {
@@ -165,7 +166,7 @@ int Lighting_Output_Decode_Lighting_Command(
             apdu_len += len;
             len = decode_real(&apdu[apdu_len], &real_value);
             apdu_len += len;
-            data->level = real_value;
+            data->level = (uint8_t)real_value;
             /* FIXME: are we going to flag errors in decoding values here? */
         }
         /* FIXME: finish me! */
@@ -561,7 +562,7 @@ bool Lighting_Output_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_VALUE_OUT_OF_RANGE;
                 }
-            } else if (value.tag == BACNET_APPLICATION_TAG_NULL) {
+            } else if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_NULL, error_class, error_code) == true) {
                 level = LIGHTING_LEVEL_NULL;
                 object_index =
                     Lighting_Output_Instance_To_Index
@@ -572,16 +573,14 @@ bool Lighting_Output_Write_Property(
                 if (wp_data->priority == 6) {
                     /* Command priority 6 is reserved for use by Minimum On/Off
                        algorithm and may not be used for other purposes in any
-                       object. */
+                       object.  - Note Lighting_Output_Present_Value_Relinquish()
+                       will have returned false because of this */
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_WRITE_ACCESS_DENIED;
                 } else if (!status) {
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_VALUE_OUT_OF_RANGE;
                 }
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         case PROP_LIGHTING_COMMAND:
@@ -591,16 +590,12 @@ bool Lighting_Output_Write_Property(
                 &Lighting_Command[wp_data->object_instance]);
             break;
         case PROP_OUT_OF_SERVICE:
-            if (value.tag == BACNET_APPLICATION_TAG_BOOLEAN) {
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_BOOLEAN, error_class, error_code)) == true) {
                 object_index =
                     Lighting_Output_Instance_To_Index
                     (wp_data->object_instance);
                 Lighting_Output_Out_Of_Service[object_index] =
                     value.type.Boolean;
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         default:
diff --git a/bacnet-stack/demo/object/lsp.c b/bacnet-stack/demo/object/lsp.c
index e08df9b1..25845566 100644
--- a/bacnet-stack/demo/object/lsp.c
+++ b/bacnet-stack/demo/object/lsp.c
@@ -34,6 +34,7 @@
 #include "bacapp.h"
 #include "config.h"     /* the custom stuff */
 #include "wp.h"
+#include "handlers.h"
 
 #define MAX_LIFE_SAFETY_POINTS 7
 
@@ -320,7 +321,7 @@ bool Life_Safety_Point_Write_Property(
     /* FIXME: len == 0: unable to decode? */
     switch (wp_data->object_property) {
         case PROP_MODE:
-            if (value.tag == BACNET_APPLICATION_TAG_ENUMERATED) {
+            if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_ENUMERATED, error_class, error_code) == true) {
                 if (value.type.Enumerated <= MAX_LIFE_SAFETY_MODE) {
                     object_index =
                         Life_Safety_Point_Instance_To_Index
@@ -332,22 +333,15 @@ bool Life_Safety_Point_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_VALUE_OUT_OF_RANGE;
                 }
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         case PROP_OUT_OF_SERVICE:
-            if (value.tag == BACNET_APPLICATION_TAG_BOOLEAN) {
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_BOOLEAN, error_class, error_code)) == true) {
                 object_index =
                     Life_Safety_Point_Instance_To_Index
                     (wp_data->object_instance);
                 Life_Safety_Point_Out_Of_Service[object_index] =
                     value.type.Boolean;
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         default:
diff --git a/bacnet-stack/demo/object/ms-input.c b/bacnet-stack/demo/object/ms-input.c
index f9fa30b9..f1d8a9cb 100644
--- a/bacnet-stack/demo/object/ms-input.c
+++ b/bacnet-stack/demo/object/ms-input.c
@@ -34,6 +34,7 @@
 #include "bacapp.h"
 #include "config.h"     /* the custom stuff */
 #include "wp.h"
+#include "handlers.h"
 
 #ifndef MAX_MULTISTATE_INPUTS
 #define MAX_MULTISTATE_INPUTS 1
@@ -472,7 +473,7 @@ bool Multistate_Input_Write_Property(
     /* FIXME: len == 0: unable to decode? */
     switch (wp_data->object_property) {
         case PROP_PRESENT_VALUE:
-            if (value.tag == BACNET_APPLICATION_TAG_UNSIGNED_INT) {
+            if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_UNSIGNED_INT, error_class, error_code) == true) {
                 if (Out_Of_Service[object_index]) {
                     if (Multistate_Input_Present_Value_Set(wp_data->
                             object_instance, value.type.Unsigned_Int)) {
@@ -485,21 +486,14 @@ bool Multistate_Input_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_WRITE_ACCESS_DENIED;
                 }
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         case PROP_OUT_OF_SERVICE:
-            if (value.tag == BACNET_APPLICATION_TAG_BOOLEAN) {
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_BOOLEAN, error_class, error_code)) == true) {
                 object_index =
                     Multistate_Input_Instance_To_Index
                     (wp_data->object_instance);
                 Out_Of_Service[object_index] = value.type.Boolean;
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         default:
diff --git a/bacnet-stack/demo/object/mso.c b/bacnet-stack/demo/object/mso.c
index d309f896..a70e7910 100644
--- a/bacnet-stack/demo/object/mso.c
+++ b/bacnet-stack/demo/object/mso.c
@@ -34,6 +34,7 @@
 #include "bacapp.h"
 #include "config.h"     /* the custom stuff */
 #include "wp.h"
+#include "handlers.h"
 
 #define MAX_MULTISTATE_OUTPUTS 4
 
@@ -393,7 +394,7 @@ bool Multistate_Output_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_VALUE_OUT_OF_RANGE;
                 }
-            } else if (value.tag == BACNET_APPLICATION_TAG_NULL) {
+            } else if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_NULL, error_class, error_code) == true) {
                 level = MULTISTATE_NULL;
                 object_index =
                     Multistate_Output_Instance_To_Index
@@ -414,22 +415,15 @@ bool Multistate_Output_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_VALUE_OUT_OF_RANGE;
                 }
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         case PROP_OUT_OF_SERVICE:
-            if (value.tag == BACNET_APPLICATION_TAG_BOOLEAN) {
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_BOOLEAN, error_class, error_code)) == true) {
                 object_index =
                     Multistate_Output_Instance_To_Index
                     (wp_data->object_instance);
                 Multistate_Output_Out_Of_Service[object_index] =
                     value.type.Boolean;
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
         default:
diff --git a/bacnet-stack/demo/object/trendlog.c b/bacnet-stack/demo/object/trendlog.c
index 05d801e2..559d5a5e 100644
--- a/bacnet-stack/demo/object/trendlog.c
+++ b/bacnet-stack/demo/object/trendlog.c
@@ -531,7 +531,7 @@ bool Trend_Log_Write_Property(
 
     switch (wp_data->object_property) {
         case PROP_ENABLE:
-            if (value.tag == BACNET_APPLICATION_TAG_BOOLEAN) {
+            if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_BOOLEAN, error_class, error_code) == true) {
                 /* Section 12.25.5 can't enable a full log with stop when full set */
                 if((CurrentLog->bEnable       == false) &&
                    (CurrentLog->bStopWhenFull == true) &&
@@ -561,16 +561,12 @@ bool Trend_Log_Write_Property(
                         }
                     }
                 }
-                
                 status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
 
         case PROP_STOP_WHEN_FULL:
-            if (value.tag == BACNET_APPLICATION_TAG_BOOLEAN) {
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_BOOLEAN, error_class, error_code)) == true) {
                 /* Only trigger this on a change of state */
                 if(CurrentLog->bStopWhenFull != value.type.Boolean) {
                     CurrentLog->bStopWhenFull = value.type.Boolean;
@@ -586,10 +582,6 @@ bool Trend_Log_Write_Property(
                         TL_Insert_Status_Rec(wp_data->object_instance, LOG_STATUS_LOG_DISABLED, true);
                     }
                 }    
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
 
@@ -603,17 +595,13 @@ bool Trend_Log_Write_Property(
             break;
 
         case PROP_RECORD_COUNT:
-            if (value.tag == BACNET_APPLICATION_TAG_UNSIGNED_INT) {
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_UNSIGNED_INT, error_class, error_code)) == true) {
                 if(value.type.Unsigned_Int == 0) {
                     /* Time to clear down the log */
                     CurrentLog->ulRecordCount = 0;
                     CurrentLog->iIndex = 0;
                     TL_Insert_Status_Rec(wp_data->object_instance, LOG_STATUS_BUFFER_PURGED, true);
                 }
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
 
@@ -622,7 +610,7 @@ bool Trend_Log_Write_Property(
              * triggered and polled options.
              */ 
         
-            if (value.tag == BACNET_APPLICATION_TAG_ENUMERATED) {
+            if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_ENUMERATED, error_class, error_code) == true) {
                 if(value.type.Enumerated != LOGGING_TYPE_COV) {
                     CurrentLog->LoggingType = value.type.Enumerated;
                     if(value.type.Enumerated == LOGGING_TYPE_POLLED) {
@@ -641,26 +629,20 @@ bool Trend_Log_Write_Property(
                     *error_class = ERROR_CLASS_PROPERTY;
                     *error_code = ERROR_CODE_OPTIONAL_FUNCTIONALITY_NOT_SUPPORTED;
                 }                
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
 
         case PROP_START_TIME:
             /* Copy the date part to safe place */
-            if (value.tag == BACNET_APPLICATION_TAG_DATE) {
-                TempDate = value.type.Date;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
+            if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_DATE, error_class, error_code) == false)
                 break;
-            }
-            /* Then decode the time part */
+
+            TempDate = value.type.Date;
+                        /* Then decode the time part */
             len = bacapp_decode_application_data(wp_data->application_data + len,
                 wp_data->application_data_len - len, &value);
                 
-            if (len && value.tag == BACNET_APPLICATION_TAG_TIME) {
+            if (len && ((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_TIME, error_class, error_code)) == true)) {
                 /* First record the current enable state of the log */
                 bEffectiveEnable = TL_Is_Enabled(wp_data->object_instance);
                 CurrentLog->StartTime.date = TempDate; /* Safe to copy the date now */
@@ -686,27 +668,20 @@ bool Trend_Log_Write_Property(
                         TL_Insert_Status_Rec(wp_data->object_instance, LOG_STATUS_LOG_DISABLED, false);
                     }
                 }    
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
 
         case PROP_STOP_TIME:
             /* Copy the date part to safe place */
-            if (value.tag == BACNET_APPLICATION_TAG_DATE) {
-                TempDate = value.type.Date;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
+            if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_DATE, error_class, error_code) == false)
                 break;
-            }
+
+            TempDate = value.type.Date;
             /* Then decode the time part */
             len = bacapp_decode_application_data(wp_data->application_data + len,
                 wp_data->application_data_len - len, &value);
                 
-            if (len && value.tag == BACNET_APPLICATION_TAG_TIME) {
+            if (len && ((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_TIME, error_class, error_code)) == true)) {
                 /* First record the current enable state of the log */
                 bEffectiveEnable = TL_Is_Enabled(wp_data->object_instance);
                 CurrentLog->StopTime.date = TempDate; /* Safe to copy the date now */
@@ -732,10 +707,6 @@ bool Trend_Log_Write_Property(
                         TL_Insert_Status_Rec(wp_data->object_instance, LOG_STATUS_LOG_DISABLED, false);
                     }
                 }    
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;
 
@@ -826,46 +797,38 @@ bool Trend_Log_Write_Property(
                 /* Read only if triggered log so flag error and bail out */
                 *error_class = ERROR_CLASS_PROPERTY;
                 *error_code = ERROR_CODE_WRITE_ACCESS_DENIED;
-            } else if((CurrentLog->LoggingType == LOGGING_TYPE_POLLED) &&
-                      (value.tag == BACNET_APPLICATION_TAG_UNSIGNED_INT) &&
-                      (value.type.Unsigned_Int == 0)) {
+                break;
+            }
+
+            if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_UNSIGNED_INT, error_class, error_code) == true) {
+                if((CurrentLog->LoggingType == LOGGING_TYPE_POLLED) && (value.type.Unsigned_Int == 0)) {
                 /* We don't support COV at the moment so don't allow switching
                  * to it by clearing interval whilst in polling mode */
                 *error_class = ERROR_CLASS_PROPERTY;
                 *error_code = ERROR_CODE_OPTIONAL_FUNCTIONALITY_NOT_SUPPORTED;
-            } else if (value.tag == BACNET_APPLICATION_TAG_UNSIGNED_INT) {
-            /* We only log to 1 sec accuracy so must divide by 100 before passing it on */
-                CurrentLog->ulLogInterval = value.type.Unsigned_Int / 100;
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
+                } else {
+                    /* We only log to 1 sec accuracy so must divide by 100 before passing it on */
+                    CurrentLog->ulLogInterval = value.type.Unsigned_Int / 100;
+                    status = true;
+                }
             }
             break;
 
         case PROP_ALIGN_INTERVALS:
-            if (value.tag == BACNET_APPLICATION_TAG_BOOLEAN) {
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_BOOLEAN, error_class, error_code)) == true)
                 CurrentLog->bAlignIntervals = value.type.Boolean;
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
-            }
+
             break;
             
         case PROP_INTERVAL_OFFSET:
             /* We only log to 1 sec accuracy so must divide by 100 before passing it on */
-            if (value.tag == BACNET_APPLICATION_TAG_UNSIGNED_INT) {
+            if((status = WPValidateArgType(&value, BACNET_APPLICATION_TAG_UNSIGNED_INT, error_class, error_code)) == true)
                 CurrentLog->ulIntervalOffset = value.type.Unsigned_Int / 100;
-                status = true;
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
-            }
+
             break;
             
         case PROP_TRIGGER:
-            if (value.tag == BACNET_APPLICATION_TAG_BOOLEAN) {
+            if(WPValidateArgType(&value, BACNET_APPLICATION_TAG_BOOLEAN, error_class, error_code) == true) {
                 /* We will not allow triggered operation if polling with aligning
                  * to the clock as that will produce non aligned readings which
                  * goes against the reason for selscting this mode
@@ -878,9 +841,6 @@ bool Trend_Log_Write_Property(
                     CurrentLog->bTrigger = value.type.Boolean;
                     status = true;
                 }
-            } else {
-                *error_class = ERROR_CLASS_PROPERTY;
-                *error_code = ERROR_CODE_INVALID_DATA_TYPE;
             }
             break;