diff -r 2b90514edfbf -r 2d1cc4f5e4ef plcopen/BlockInstanceCollector.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/plcopen/BlockInstanceCollector.py	Fri Feb 23 11:16:25 2018 +0100
@@ -0,0 +1,188 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# This file is part of Beremiz.
+# See COPYING file for copyrights details.
+
+from __future__ import absolute_import
+from plcopen.XSLTModelQuery import XSLTModelQuery, _StringValue, _BoolValue, _translate_args
+from collections import OrderedDict, namedtuple
+
+# -------------------------------------------------------------------------------
+#           Helpers object for generating pou block instances list
+# -------------------------------------------------------------------------------
+
+
+_Point = namedtuple("Point", ["x", "y"])
+
+_BlockInstanceInfos = namedtuple(
+    "BlockInstanceInfos",
+    ["type", "id", "x", "y", "width", "height", "specific_values", "inputs", "outputs"])
+
+_BlockSpecificValues = (
+    namedtuple("BlockSpecificValues",
+               ["name", "execution_order"]),
+    [_StringValue, int])
+_VariableSpecificValues = (
+    namedtuple("VariableSpecificValues",
+               ["name", "value_type", "execution_order"]),
+    [_StringValue, _StringValue, int])
+_ConnectionSpecificValues = (
+    namedtuple("ConnectionSpecificValues", ["name"]),
+    [_StringValue])
+
+_PowerRailSpecificValues = (
+    namedtuple("PowerRailSpecificValues", ["connectors"]),
+    [int])
+
+_LDElementSpecificValues = (
+    namedtuple("LDElementSpecificValues",
+               ["name", "negated", "edge", "storage", "execution_order"]),
+    [_StringValue, _BoolValue, _StringValue, _StringValue, int])
+
+_DivergenceSpecificValues = (
+    namedtuple("DivergenceSpecificValues", ["connectors"]),
+    [int])
+
+_SpecificValuesTuples = {
+    "comment": (
+        namedtuple("CommentSpecificValues", ["content"]),
+        [_StringValue]),
+    "input": _VariableSpecificValues,
+    "output": _VariableSpecificValues,
+    "inout": _VariableSpecificValues,
+    "connector": _ConnectionSpecificValues,
+    "continuation": _ConnectionSpecificValues,
+    "leftPowerRail": _PowerRailSpecificValues,
+    "rightPowerRail": _PowerRailSpecificValues,
+    "contact": _LDElementSpecificValues,
+    "coil": _LDElementSpecificValues,
+    "step": (
+        namedtuple("StepSpecificValues", ["name", "initial", "action"]),
+        [_StringValue, _BoolValue, lambda x: x]),
+    "transition": (
+        namedtuple("TransitionSpecificValues",
+                   ["priority", "condition_type", "condition", "connection"]),
+        [int, _StringValue, _StringValue, lambda x: x]),
+    "selectionDivergence": _DivergenceSpecificValues,
+    "selectionConvergence": _DivergenceSpecificValues,
+    "simultaneousDivergence": _DivergenceSpecificValues,
+    "simultaneousConvergence": _DivergenceSpecificValues,
+    "jump": (
+        namedtuple("JumpSpecificValues", ["target"]),
+        [_StringValue]),
+    "actionBlock": (
+        namedtuple("ActionBlockSpecificValues", ["actions"]),
+        [lambda x: x]),
+}
+
+_InstanceConnectionInfos = namedtuple(
+    "InstanceConnectionInfos",
+    ["name", "negated", "edge", "position", "links"])
+
+_ConnectionLinkInfos = namedtuple(
+    "ConnectionLinkInfos",
+    ["refLocalId", "formalParameter", "points"])
+
+
+class _ActionInfos(object):
+    __slots__ = ["qualifier", "type", "value", "duration", "indicator"]
+
+    def __init__(self, *args):
+        for attr, value in zip(self.__slots__, args):
+            setattr(self, attr, value if value is not None else "")
+
+    def copy(self):
+        return _ActionInfos(*[getattr(self, attr) for attr in self.__slots__])
+
+
+class BlockInstanceFactory(object):
+
+    def __init__(self, block_instances):
+        self.BlockInstances = block_instances
+        self.CurrentInstance = None
+        self.SpecificValues = None
+        self.CurrentConnection = None
+        self.CurrentLink = None
+
+    def SetSpecificValues(self, context, *args):
+        self.SpecificValues = list(args)
+        self.CurrentInstance = None
+        self.CurrentConnection = None
+        self.CurrentLink = None
+
+    def AddBlockInstance(self, context, *args):
+        specific_values_tuple, specific_values_translation = \
+            _SpecificValuesTuples.get(args[0][0], _BlockSpecificValues)
+
+        if args[0][0] == "step" and len(self.SpecificValues) < 3 or \
+           args[0][0] == "transition" and len(self.SpecificValues) < 4:
+            self.SpecificValues.append([None])
+        elif args[0][0] == "actionBlock" and len(self.SpecificValues) < 1:
+            self.SpecificValues.append([[]])
+        specific_values = specific_values_tuple(*_translate_args(
+            specific_values_translation, self.SpecificValues))
+        self.SpecificValues = None
+
+        self.CurrentInstance = _BlockInstanceInfos(
+            *(_translate_args([_StringValue, int] + [float] * 4, args) +
+              [specific_values, [], []]))
+
+        self.BlockInstances[self.CurrentInstance.id] = self.CurrentInstance
+
+    def AddInstanceConnection(self, context, *args):
+        connection_args = _translate_args(
+            [_StringValue] * 2 + [_BoolValue, _StringValue] + [float] * 2, args)
+
+        self.CurrentConnection = _InstanceConnectionInfos(
+            *(connection_args[1:4] + [
+                _Point(*connection_args[4:6]), []]))
+
+        if self.CurrentInstance is not None:
+            if connection_args[0] == "input":
+                self.CurrentInstance.inputs.append(self.CurrentConnection)
+            else:
+                self.CurrentInstance.outputs.append(self.CurrentConnection)
+        else:
+            self.SpecificValues.append([self.CurrentConnection])
+
+    def AddConnectionLink(self, context, *args):
+        self.CurrentLink = _ConnectionLinkInfos(
+            *(_translate_args([int, _StringValue], args) + [[]]))
+        self.CurrentConnection.links.append(self.CurrentLink)
+
+    def AddLinkPoint(self, context, *args):
+        self.CurrentLink.points.append(_Point(
+            *_translate_args([float] * 2, args)))
+
+    def AddAction(self, context, *args):
+        if len(self.SpecificValues) == 0:
+            self.SpecificValues.append([[]])
+        translated_args = _translate_args([_StringValue] * 5, args)
+        self.SpecificValues[0][0].append(_ActionInfos(*translated_args))
+
+
+class BlockInstanceCollector(XSLTModelQuery):
+    """ object for collecting instances path list"""
+    def __init__(self, controller):
+        XSLTModelQuery.__init__(self,
+                                controller,
+                                "pou_block_instances.xslt",
+                                [(name, self.FactoryCaller(name))
+                                 for name in ["AddBlockInstance",
+                                              "SetSpecificValues",
+                                              "AddInstanceConnection",
+                                              "AddConnectionLink",
+                                              "AddLinkPoint",
+                                              "AddAction"]])
+
+    def FactoryCaller(self, funcname):
+        def CallFactory(*args):
+            return getattr(self.factory, funcname)(*args)
+        return CallFactory
+
+    def Collect(self, root, debug):
+        element_instances = OrderedDict()
+        self.factory = BlockInstanceFactory(element_instances)
+        self._process_xslt(root, debug)
+        self.factory = None
+        return element_instances