diff --git a/sw/ground_segment/python/messages_app/messagesframe.py b/sw/ground_segment/python/messages_app/messagesframe.py
index d36fe44a7c..d51b26c02e 100644
--- a/sw/ground_segment/python/messages_app/messagesframe.py
+++ b/sw/ground_segment/python/messages_app/messagesframe.py
@@ -14,7 +14,7 @@ sys.path.append(PPRZ_SRC + "/sw/lib/python")
 PPRZ_HOME = getenv("PAPARAZZI_HOME", PPRZ_SRC)
 
 from ivy_msg_interface import IvyMessagesInterface
-import messages_xml_map
+from pprz_msg.message import PprzMessage
 
 WIDTH = 450
 LABEL_WIDTH = 166
@@ -23,18 +23,16 @@ HEIGHT = 800
 BORDER = 1
 
 
-class Message:
+class Message(PprzMessage):
     def __init__(self, class_name, name):
-        messages_xml_map.parse_messages()
-        self.field_value = []
-        self.field_names = messages_xml_map.message_dictionary[class_name][name]
+        super(Message, self).__init__(class_name, name)
         self.field_controls = []
         self.index = None
         self.last_seen = time.clock()
         self.name = name
 
 
-class Aircraft:
+class Aircraft(object):
     def __init__(self, ac_id):
         self.ac_id = ac_id
         self.messages = {}
@@ -42,7 +40,7 @@ class Aircraft:
 
 
 class MessagesFrame(wx.Frame):
-    def message_recv(self, msg_class, msg_name, ac_id, values):
+    def message_recv(self, msg_class, msg_name, ac_id, msg):
         """Handle incoming messages
 
         Callback function for IvyMessagesInterface
@@ -53,8 +51,8 @@ class MessagesFrame(wx.Frame):
         :type msg_name: str
         :param ac_id: aircraft id
         :type ac_id: int
-        :param values: message values
-        :type values: list
+        :param msg: message
+        :type msg: PprzMessage
         """
         # only show messages of the requested class
         if msg_class != self.msg_class:
@@ -62,7 +60,7 @@ class MessagesFrame(wx.Frame):
         if ac_id in self.aircrafts and msg_name in self.aircrafts[ac_id].messages:
             if time.time() - self.aircrafts[ac_id].messages[msg_name].last_seen < 0.2:
                 return
-        wx.CallAfter(self.gui_update, msg_class, msg_name, ac_id, values)
+        wx.CallAfter(self.gui_update, msg_class, msg_name, ac_id, msg)
 
     def find_page(self, book, name):
         if book.GetPageCount() < 1:
@@ -119,7 +117,7 @@ class MessagesFrame(wx.Frame):
         messages_book = aircraft.messages_book
         aircraft.messages[name] = Message(msg_class, name)
         field_panel = wx.Panel(messages_book)
-        grid_sizer = wx.FlexGridSizer(len(aircraft.messages[name].field_names), 2)
+        grid_sizer = wx.FlexGridSizer(len(aircraft.messages[name].get_fieldnames()), 2)
 
         index = self.find_page(messages_book, name)
         messages_book.InsertPage(index, field_panel, name, imageId=1)
@@ -129,7 +127,7 @@ class MessagesFrame(wx.Frame):
         for message_name in aircraft.messages:
             aircraft.messages[message_name].index = self.find_page(messages_book, message_name)
 
-        for field_name in aircraft.messages[name].field_names:
+        for field_name in aircraft.messages[name].get_fieldnames():
             name_text = wx.StaticText(field_panel, -1, field_name)
             size = name_text.GetSize()
             size.x = LABEL_WIDTH
@@ -147,7 +145,7 @@ class MessagesFrame(wx.Frame):
         field_panel.SetSizer(grid_sizer)
         field_panel.Layout()
 
-    def gui_update(self, msg_class, msg_name, ac_id, values):
+    def gui_update(self, msg_class, msg_name, ac_id, msg):
         if ac_id not in self.aircrafts:
             self.add_new_aircraft(ac_id)
 
@@ -159,8 +157,8 @@ class MessagesFrame(wx.Frame):
         aircraft.messages_book.SetPageImage(aircraft.messages[msg_name].index, 1)
         self.aircrafts[ac_id].messages[msg_name].last_seen = time.time()
 
-        for index in range(0, len(values)):
-            aircraft.messages[msg_name].field_controls[index].SetLabel(values[index])
+        for index in range(0, len(msg.get_fieldvalues())):
+            aircraft.messages[msg_name].field_controls[index].SetLabel(msg.get_field(index))
 
     def __init__(self, msg_class="telemetry"):
         wx.Frame.__init__(self, id=-1, parent=None, name=u'MessagesFrame', size=wx.Size(WIDTH, HEIGHT), style=wx.DEFAULT_FRAME_STYLE, title=u'Messages')
diff --git a/sw/lib/python/ivy_msg_interface.py b/sw/lib/python/ivy_msg_interface.py
index 62130146ae..f44a1c606f 100644
--- a/sw/lib/python/ivy_msg_interface.py
+++ b/sw/lib/python/ivy_msg_interface.py
@@ -6,9 +6,17 @@ import os
 import sys
 import re
 
+# if PAPARAZZI_SRC not set, then assume the tree containing this
+# file is a reasonable substitute
+PPRZ_SRC = os.getenv("PAPARAZZI_SRC", os.path.normpath(os.path.join(os.path.dirname(os.path.abspath(__file__)),
+                                                                    '../../../../')))
+sys.path.append(PPRZ_SRC + "/sw/lib/python")
 
-class IvyMessagesInterface():
-    def __init__(self, callback, init=True, verbose=True, bind_regex="(.*)"):
+from pprz_msg.message import PprzMessage
+
+
+class IvyMessagesInterface(object):
+    def __init__(self, callback, init=True, verbose=False, bind_regex='(.*)'):
         self.callback = callback
         self.ivy_id = 0
         self.verbose = verbose
@@ -27,7 +35,7 @@ class IvyMessagesInterface():
         except:
             pass
 
-    def init_ivy(self, init, bind_regex):
+    def init_ivy(self, init=True, bind_regex='(.*)'):
         if init:
             IvyInit("Messages %i" % os.getpid(), "READY", 0, lambda x,y: y, lambda x,y: y)
             logging.getLogger('Ivy').setLevel(logging.WARN)
@@ -56,13 +64,16 @@ class IvyMessagesInterface():
 
         # check which message class it is
         # pass non-telemetry messages with ac_id 0
-        if data[0] in ["ground", "ground_dl", "dl"]:
+        if data[0] in ["sim", "ground_dl", "dl"]:
+            if self.verbose:
+                    print("ignoring message " + ' '.join(data))
+                    sys.stdout.flush()
+            return
+        elif data[0] in ["ground"]:
             msg_class = data[0]
             msg_name = data[1]
             ac_id = 0
             values = list(filter(None, data[2:]))
-        elif data[0] == "sim":
-            return
         else:
             try:
                 ac_id = int(data[0])
@@ -74,4 +85,6 @@ class IvyMessagesInterface():
             msg_class = "telemetry"
             msg_name = data[1]
             values = list(filter(None, data[2:]))
-        self.callback(msg_class, msg_name, ac_id, values)
+        msg = PprzMessage(msg_class, msg_name)
+        msg.set_values(values)
+        self.callback(msg_class, msg_name, ac_id, msg)
diff --git a/sw/lib/python/pprz_msg/__init__.py b/sw/lib/python/pprz_msg/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/sw/lib/python/pprz_msg/message.py b/sw/lib/python/pprz_msg/message.py
new file mode 100644
index 0000000000..202ed6955f
--- /dev/null
+++ b/sw/lib/python/pprz_msg/message.py
@@ -0,0 +1,62 @@
+"""
+Paparazzi message representation
+
+"""
+
+from __future__ import print_function
+import sys
+import json
+import messages_xml_map
+
+
+class PprzMessageError(Exception):
+    def __init__(self, message, inner_exception=None):
+        self.message = message
+        self.inner_exception = inner_exception
+        self.exception_info = sys.exc_info()
+    def __str__(self):
+        return self.message
+
+
+class PprzMessage(object):
+    """base Paparazzi message class"""
+    def __init__(self, class_name, name):
+        self._class_name = class_name
+        self._name = name
+        self._id = messages_xml_map.get_msg_id(class_name, name)
+        self._fieldnames = messages_xml_map.get_msg_fields(class_name, name)
+        self._fieldvalues = []
+
+    def get_fieldnames(self):
+        return self._fieldnames
+
+    def get_fieldvalues(self):
+        return self._fieldvalues
+
+    def get_field(self, idx):
+        return self._fieldvalues[idx]
+
+    def set_values(self, values):
+        if len(values) == len(self._fieldnames):
+            self._fieldvalues = values
+        else:
+            raise PprzMessageError("Error: fields not matching")
+
+    def __str__(self):
+        ret = '%s.%s {' % (self._class_name, self._name)
+        for idx, f in enumerate(self._fieldnames):
+            ret += '%s : %s, ' % (f, self._fieldvalues[idx])
+        ret = ret[0:-2] + '}'
+        return ret
+
+    def to_dict(self, payload_only=False):
+        d = {}
+        if not payload_only:
+            d['msgname'] = self._name
+            d['msgclass'] = self._class_name
+        for idx, f in enumerate(self._fieldnames):
+            d[f] = self._fieldvalues[idx]
+        return d
+
+    def to_json(self, payload_only=False):
+        return json.dumps(self.to_dict(payload_only))
diff --git a/sw/lib/python/messages_xml_map.py b/sw/lib/python/pprz_msg/messages_xml_map.py
similarity index 80%
rename from sw/lib/python/messages_xml_map.py
rename to sw/lib/python/pprz_msg/messages_xml_map.py
index c24d7c5cc5..1a8cdb1294 100755
--- a/sw/lib/python/messages_xml_map.py
+++ b/sw/lib/python/pprz_msg/messages_xml_map.py
@@ -7,7 +7,7 @@ import os
 # if PAPARAZZI_HOME not set, then assume the tree containing this
 # file is a reasonable substitute
 PPRZ_HOME = os.getenv("PAPARAZZI_HOME", os.path.normpath(os.path.join(os.path.dirname(os.path.abspath(__file__)),
-                                                                      '../../../')))
+                                                                      '../../../..')))
 
 default_messages_file = '%s/conf/messages.xml' % PPRZ_HOME
 
@@ -61,6 +61,30 @@ def parse_messages(messages_file=default_messages_file):
                 message_dictionary_types[class_name][message_id].append(the_field.attrib['type'])
 
 
+def get_msg_fields(msg_class, msg_name):
+    if not message_dictionary:
+        parse_messages()
+    if msg_class in message_dictionary:
+        if msg_name in message_dictionary[msg_class]:
+            return message_dictionary[msg_class][msg_name]
+        else:
+            print("Error: msg_name %s not found in msg_class %s." % (msg_name, msg_class))
+    else:
+        print("Error: msg_class %s not found." % msg_class)
+    return []
+
+
+def get_msg_id(msg_class, msg_name):
+    if not message_dictionary:
+        parse_messages()
+    try:
+        return message_dictionary_name_id[msg_class][msg_name]
+    except KeyError:
+        print("Error: msg_name %s not found in msg_class %s." % (msg_name, msg_class))
+        return 0
+
+
+
 def test():
     import argparse
     parser = argparse.ArgumentParser()