diff --git a/py25/bacpypes/service/detect.py b/py25/bacpypes/service/detect.py
new file mode 100755
index 0000000..4867d27
--- /dev/null
+++ b/py25/bacpypes/service/detect.py
@@ -0,0 +1,146 @@
+#!/usr/bin/env python
+
+"""
+Detection
+"""
+
+from bacpypes.debugging import bacpypes_debugging, ModuleLogger
+
+from bacpypes.core import deferred
+
+# some debugging
+_debug = 0 
+_log = ModuleLogger(globals())
+
+#
+#   DetectionMonitor
+#
+
+class DetectionMonitor:
+
+    def __init__(self, algorithm, parameter, obj, prop, filter=None):
+        if _debug: DetectionMonitor._debug("__init__ ...")
+
+        # keep track of the parameter values
+        self.algorithm = algorithm
+        self.parameter = parameter
+        self.obj = obj
+        self.prop = prop
+        self.filter = None
+
+    def property_change(self, old_value, new_value):
+        if _debug: DetectionMonitor._debug("property_change %r %r", old_value, new_value)
+
+        # set the parameter value
+        setattr(self.algorithm, self.parameter, new_value)
+
+        # if the algorithm is already triggered, don't bother checking for more
+        if self.algorithm._triggered:
+            if _debug: DetectionMonitor._debug("    - already triggered")
+            return
+
+        # if there is a special filter, use it, otherwise use !=
+        if self.filter:
+            trigger = self.filter(old_value, new_value)
+        else:
+            trigger = (old_value != new_value)
+        if _debug: DetectionMonitor._debug("    - trigger: %r", trigger)
+
+        # trigger it
+        if trigger:
+            deferred(self.algorithm._execute)
+            if _debug: DetectionMonitor._debug("    - deferred: %r", self.algorithm._execute)
+
+            self.algorithm._triggered = True
+
+bacpypes_debugging(DetectionMonitor)
+
+#
+#   monitor_filter
+#
+
+def monitor_filter(parameter):
+    def transfer_filter_decorator(fn):
+        fn._monitor_filter = parameter
+        return fn
+
+    return transfer_filter_decorator
+
+#
+#   DetectionAlgorithm
+#
+
+class DetectionAlgorithm:
+
+    def __init__(self):
+        if _debug: DetectionAlgorithm._debug("__init__")
+
+        # monitor objects
+        self._monitors = []
+
+        # triggered flag, set when a parameter changed and the monitor
+        # schedules the algorithm to execute
+        self._triggered = False
+
+    def bind(self, **kwargs):
+        if _debug: DetectionAlgorithm._debug("bind %r", kwargs)
+
+        # build a map of methods that are filters.  These have been decorated
+        # with monitor_filter, but they are unbound methods (or simply
+        # functions in Python3) at the time they are decorated but by looking
+        # for them now they are bound to this instance.
+        monitor_filters = {}
+        for attr_name in dir(self):
+            attr = getattr(self, attr_name)
+            if hasattr(attr, "_monitor_filter"):
+                monitor_filters[attr._monitor_filter] = attr
+        if _debug: DetectionAlgorithm._debug("    - monitor_filters: %r", monitor_filters)
+
+        for parameter, (obj, prop) in kwargs.items():
+            if not hasattr(self, parameter):
+                if _debug: DetectionAlgorithm._debug("    - no matching parameter: %r", parameter)
+
+            # make a detection monitor
+            monitor = DetectionMonitor(self, parameter, obj, prop)
+            if _debug: DetectionAlgorithm._debug("    - monitor: %r", monitor)
+
+            # check to see if there is a custom filter for it
+            if parameter in monitor_filters:
+                monitor.filter = monitor_filters[parameter]
+
+            # keep track of all of these objects for if/when we unbind
+            self._monitors.append(monitor)
+
+            # add the property value monitor function
+            obj._property_monitors[prop].append(monitor.property_change)
+
+            # set the parameter value to the property value if it's not None
+            property_value = obj._values[prop]
+            if property_value is not None:
+                if _debug: DetectionAlgorithm._debug("    - %s: %r", parameter, property_value)
+                setattr(self, parameter, property_value)
+
+    def unbind(self):
+        if _debug: DetectionAlgorithm._debug("unbind")
+
+        # remove the property value monitor functions
+        for monitor in self._monitors:
+            if _debug: DetectionAlgorithm._debug("    - monitor: %r", monitor)
+            monitor.obj._property_monitors[monitor.prop].remove(monitor.property_change)
+
+        # abandon the array
+        self._monitors = []
+
+    def _execute(self):
+        if _debug: DetectionAlgorithm._debug("_execute")
+
+        # provided by the derived class
+        self.execute()
+
+        # turn the trigger off
+        self._triggered = False
+
+    def execute(self):
+        raise NotImplementedError("execute not implemented")
+
+bacpypes_debugging(DetectionAlgorithm)
\ No newline at end of file
diff --git a/py34/bacpypes/service/detect.py b/py34/bacpypes/service/detect.py
new file mode 100755
index 0000000..503bb15
--- /dev/null
+++ b/py34/bacpypes/service/detect.py
@@ -0,0 +1,144 @@
+#!/usr/bin/env python
+
+"""
+Detection
+"""
+
+from bacpypes.debugging import bacpypes_debugging, ModuleLogger
+
+from bacpypes.core import deferred
+
+# some debugging
+_debug = 0 
+_log = ModuleLogger(globals())
+
+#
+#   DetectionMonitor
+#
+
+@bacpypes_debugging
+class DetectionMonitor:
+
+    def __init__(self, algorithm, parameter, obj, prop, filter=None):
+        if _debug: DetectionMonitor._debug("__init__ ...")
+
+        # keep track of the parameter values
+        self.algorithm = algorithm
+        self.parameter = parameter
+        self.obj = obj
+        self.prop = prop
+        self.filter = None
+
+    def property_change(self, old_value, new_value):
+        if _debug: DetectionMonitor._debug("property_change %r %r", old_value, new_value)
+
+        # set the parameter value
+        setattr(self.algorithm, self.parameter, new_value)
+
+        # if the algorithm is already triggered, don't bother checking for more
+        if self.algorithm._triggered:
+            if _debug: DetectionMonitor._debug("    - already triggered")
+            return
+
+        # if there is a special filter, use it, otherwise use !=
+        if self.filter:
+            trigger = self.filter(old_value, new_value)
+        else:
+            trigger = (old_value != new_value)
+        if _debug: DetectionMonitor._debug("    - trigger: %r", trigger)
+
+        # trigger it
+        if trigger:
+            deferred(self.algorithm._execute)
+            if _debug: DetectionMonitor._debug("    - deferred: %r", self.algorithm._execute)
+
+            self.algorithm._triggered = True
+
+#
+#   monitor_filter
+#
+
+def monitor_filter(parameter):
+    def transfer_filter_decorator(fn):
+        fn._monitor_filter = parameter
+        return fn
+
+    return transfer_filter_decorator
+
+#
+#   DetectionAlgorithm
+#
+
+@bacpypes_debugging
+class DetectionAlgorithm:
+
+    def __init__(self):
+        if _debug: DetectionAlgorithm._debug("__init__")
+
+        # monitor objects
+        self._monitors = []
+
+        # triggered flag, set when a parameter changed and the monitor
+        # schedules the algorithm to execute
+        self._triggered = False
+
+    def bind(self, **kwargs):
+        if _debug: DetectionAlgorithm._debug("bind %r", kwargs)
+
+        # build a map of methods that are filters.  These have been decorated
+        # with monitor_filter, but they are unbound methods (or simply
+        # functions in Python3) at the time they are decorated but by looking
+        # for them now they are bound to this instance.
+        monitor_filters = {}
+        for attr_name in dir(self):
+            attr = getattr(self, attr_name)
+            if hasattr(attr, "_monitor_filter"):
+                monitor_filters[attr._monitor_filter] = attr
+        if _debug: DetectionAlgorithm._debug("    - monitor_filters: %r", monitor_filters)
+
+        for parameter, (obj, prop) in kwargs.items():
+            if not hasattr(self, parameter):
+                if _debug: DetectionAlgorithm._debug("    - no matching parameter: %r", parameter)
+
+            # make a detection monitor
+            monitor = DetectionMonitor(self, parameter, obj, prop)
+            if _debug: DetectionAlgorithm._debug("    - monitor: %r", monitor)
+
+            # check to see if there is a custom filter for it
+            if parameter in monitor_filters:
+                monitor.filter = monitor_filters[parameter]
+
+            # keep track of all of these objects for if/when we unbind
+            self._monitors.append(monitor)
+
+            # add the property value monitor function
+            obj._property_monitors[prop].append(monitor.property_change)
+
+            # set the parameter value to the property value if it's not None
+            property_value = obj._values[prop]
+            if property_value is not None:
+                if _debug: DetectionAlgorithm._debug("    - %s: %r", parameter, property_value)
+                setattr(self, parameter, property_value)
+
+    def unbind(self):
+        if _debug: DetectionAlgorithm._debug("unbind")
+
+        # remove the property value monitor functions
+        for monitor in self._monitors:
+            if _debug: DetectionAlgorithm._debug("    - monitor: %r", monitor)
+            monitor.obj._property_monitors[monitor.prop].remove(monitor.property_change)
+
+        # abandon the array
+        self._monitors = []
+
+    def _execute(self):
+        if _debug: DetectionAlgorithm._debug("_execute")
+
+        # provided by the derived class
+        self.execute()
+
+        # turn the trigger off
+        self._triggered = False
+
+    def execute(self):
+        raise NotImplementedError("execute not implemented")
\ No newline at end of file