Corrected the NPDU encoding for the demo handlers.

bacnet-stack/demo/handler/s_wp.c

@@ -51,9 +51,11 @@ uint8_t Send_Write_Property_Request(uint32_t device_id, /* destination device */
     uint8_t priority, int32_t array_index)
 {
     BACNET_ADDRESS dest;
+    BACNET_ADDRESS my_address;
     unsigned max_apdu = 0;
     uint8_t invoke_id = 0;
     bool status = false;
+    int len = 0;
     int pdu_len = 0;
     int bytes_sent = 0;
     BACNET_WRITE_PROPERTY_DATA data;
@@ -68,23 +70,27 @@ uint8_t Send_Write_Property_Request(uint32_t device_id, /* destination device */
     if (status)
         invoke_id = tsm_next_free_invokeID();
     if (invoke_id) {
-        /* load the data for the encoding */
+        /* encode the NPDU portion of the packet */
+        datalink_get_my_address(&my_address);
+        npdu_encode_npdu_data(&npdu_data, true, MESSAGE_PRIORITY_NORMAL);
+        pdu_len = npdu_encode_pdu(&Handler_Transmit_Buffer[0], &dest,
+                &my_address, &npdu_data);
+        /* encode the APDU portion of the packet */
         data.object_type = object_type;
         data.object_instance = object_instance;
         data.object_property = object_property;
         data.array_index = array_index;
         bacapp_copy(&data.value, object_value);
         data.priority = priority;
-        pdu_len = wp_encode_apdu(&Handler_Transmit_Buffer[0],
+        len = wp_encode_apdu(&Handler_Transmit_Buffer[pdu_len],
             invoke_id, &data);
+        pdu_len += len;
         /* will it fit in the sender?
            note: if there is a bottleneck router in between
            us and the destination, we won't know unless
            we have a way to check for that and update the
            max_apdu in the address binding table. */
         if ((unsigned) pdu_len < max_apdu) {
-            npdu_encode_confirmed_apdu(&npdu_data,
-                MESSAGE_PRIORITY_NORMAL);
             tsm_set_confirmed_unsegmented_transaction(invoke_id, &dest,
                 &npdu_data, &Handler_Transmit_Buffer[0], pdu_len);
             bytes_sent =