diff --git a/BAC0/core/app/ScriptApplication.py b/BAC0/core/app/ScriptApplication.py
index 83a19743..5bce2508 100644
--- a/BAC0/core/app/ScriptApplication.py
+++ b/BAC0/core/app/ScriptApplication.py
@@ -23,6 +23,7 @@
 from bacpypes.app import ApplicationIOController
 from bacpypes.pdu import Address
 from bacpypes.service.object import ReadWritePropertyMultipleServices
+from bacpypes.service.cov import ChangeOfValueServices
 from bacpypes.netservice import NetworkServiceAccessPoint, NetworkServiceElement
 from bacpypes.bvllservice import (
     BIPSimple,
@@ -31,6 +32,8 @@
     AnnexJCodec,
     UDPMultiplexer,
 )
+from bacpypes.apdu import SubscribeCOVRequest, SimpleAckPDU, RejectPDU, AbortPDU
+
 from bacpypes.appservice import StateMachineAccessPoint, ApplicationServiceAccessPoint
 from bacpypes.comm import ApplicationServiceElement, bind, Client
 from bacpypes.iocb import IOCB
@@ -97,6 +100,33 @@ def do_WhoIsRequest(self, apdu):
         iocb = IOCB(self.iam_req)  # make an IOCB
         deferred(self.request_io, iocb)
 
+    def do_ConfirmedCOVNotificationRequest(self, apdu):
+        # look up the process identifier
+        context = self.subscription_contexts.get(apdu.subscriberProcessIdentifier, None)
+        if not context or apdu.pduSource != context.address:
+            # this is turned into an ErrorPDU and sent back to the client
+            raise RuntimeError("services", "unknownSubscription")
+
+        # now tell the context object
+        elements = context.cov_notification(apdu)
+
+        # success
+        response = SimpleAckPDU(context=apdu)
+
+        # return the result
+        self.response(response)
+        print(elements)
+
+    def do_UnconfirmedCOVNotificationRequest(self, apdu):
+        # look up the process identifier
+        context = self.subscription_contexts.get(apdu.subscriberProcessIdentifier, None)
+        if not context or apdu.pduSource != context.address:
+            return
+
+        # now tell the context object
+        elements = context.cov_notification(apdu)
+        print(elements)
+
 
 @note_and_log
 class BAC0Application(
@@ -106,6 +136,7 @@ class BAC0Application(
     WhoHasIHaveServices,
     ReadWritePropertyServices,
     ReadWritePropertyMultipleServices,
+    ChangeOfValueServices,
 ):
     """
     Defines a basic BACnet/IP application to process BACnet requests.
@@ -179,6 +210,9 @@ def __init__(
         self._last_i_am_received = []
         self._last_i_have_received = []
 
+        # to support CoV
+        self.subscription_contexts = {}
+
     def close_socket(self):
         # pass to the multiplexer, then down to the sockets
         self.mux.close_socket()
@@ -199,6 +233,7 @@ class BAC0ForeignDeviceApplication(
     WhoHasIHaveServices,
     ReadWritePropertyServices,
     ReadWritePropertyMultipleServices,
+    ChangeOfValueServices,
 ):
     """
     Defines a basic BACnet/IP application to process BACnet requests.
@@ -271,6 +306,9 @@ def __init__(
         self._last_i_am_received = []
         self._last_i_have_received = []
 
+        # to support CoV
+        self.subscription_contexts = {}
+
     def close_socket(self):
         # pass to the multiplexer, then down to the sockets
         self.mux.close_socket()
@@ -292,6 +330,7 @@ class BAC0BBMDDeviceApplication(
     WhoHasIHaveServices,
     ReadWritePropertyServices,
     ReadWritePropertyMultipleServices,
+    ChangeOfValueServices,
 ):
     """
     Defines a basic BACnet/IP application to process BACnet requests.
@@ -374,6 +413,9 @@ def __init__(
         self._last_i_am_received = []
         self._last_i_have_received = []
 
+        # to support CoV
+        self.subscription_contexts = {}
+
     def add_peer(self, address):
         try:
             bdt_address = Address(address)
diff --git a/BAC0/core/functions/cov.py b/BAC0/core/functions/cov.py
new file mode 100644
index 00000000..ebb0c5c0
--- /dev/null
+++ b/BAC0/core/functions/cov.py
@@ -0,0 +1,131 @@
+from bacpypes.apdu import SubscribeCOVRequest, SimpleAckPDU, RejectPDU, AbortPDU
+from bacpypes.iocb import IOCB
+from bacpypes.core import deferred
+from bacpypes.pdu import Address
+from bacpypes.object import get_object_class, get_datatype
+from bacpypes.constructeddata import Array
+from bacpypes.primitivedata import Tag, ObjectIdentifier, Unsigned
+
+from BAC0.core.io.Read import cast_datatype_from_tag
+
+"""
+
+using cov, we build a "context" which is turned into a subscription being sent to 
+the destination.
+
+Once the IOCB is over, the callback attached to it will execute (subscription_acknowledged)
+and we'll get the answer
+
+"""
+
+
+class SubscriptionContext:
+    next_proc_id = 1
+
+    def __init__(self, address, objectID, confirmed=None, lifetime=None):
+        self.address = address
+        self.subscriberProcessIdentifier = self.next_proc_id
+        self.next_proc_id += 1
+        # subscription_contexts[self.subscriberProcessIdentifier] = self
+        self.monitoredObjectIdentifier = objectID
+        self.issueConfirmedNotifications = confirmed
+        self.lifetime = lifetime
+
+    def cov_notification(self, apdu):
+        # make a rash assumption that the property value is going to be
+        # a single application encoded tag
+        source = apdu.pduSource
+        object_changed = apdu.monitoredObjectIdentifier
+
+        elements = {
+            "source": source,
+            "object_changed": object_changed,
+            "properties": {},
+        }
+        for element in apdu.listOfValues:
+            prop_id = element.propertyIdentifier
+            datatype = get_datatype(object_changed[0], prop_id)
+            value = element.value
+
+            if not datatype:
+                # raise TypeError("unknown datatype")
+                value = cast_datatype_from_tag(
+                    element.value, object_changed[0], prop_id
+                )
+            else:
+                # special case for array parts, others are managed by cast_out
+                if issubclass(datatype, Array) and (
+                    element.propertyArrayIndex is not None
+                ):
+                    if element.propertyArrayIndex == 0:
+                        value = element.value.cast_out(Unsigned)
+                    else:
+                        value = element.value.cast_out(datatype.subtype)
+                else:
+                    value = element.value.cast_out(datatype)
+
+            elements["properties"][prop_id] = value
+
+        return elements
+
+
+class CoV:
+    """
+    Mixin to support COV registration
+    """
+
+    def cov_notification(self, apdu):
+        print("do something here")
+
+    def send_cov_subscription(self, request):
+        self._log.info("Request : {}".format(request))
+        iocb = IOCB(request)
+        # iocb.add_callback(self.subscription_acknowledged)
+        self._log.info("IOCB : {}".format(iocb))
+
+        iocb.add_callback(self.subscription_acknowledged)
+
+        # pass to the BACnet stack
+        deferred(self.this_application.request_io, iocb)
+
+        # Unconfirmed request...so wait until complete
+        # iocb.wait()  # Wait for BACnet response
+
+    def subscription_acknowledged(self, iocb):
+        if iocb.ioResponse:
+            self._log.info("Subscription success")
+
+        if iocb.ioError:
+            self._log.error("Subscription failed. {}".format(iocb.ioError))
+
+    def cov(self, address, objectID, confirmed=True, lifetime=None):
+        address = Address(address)
+        context = self._build_cov_context(
+            address, objectID, confirmed=confirmed, lifetime=lifetime
+        )
+        request = self._build_cov_request(context)
+        self.send_cov_subscription(request)
+
+    def _build_cov_context(self, address, objectID, confirmed=True, lifetime=None):
+        context = SubscriptionContext(
+            address=address, objectID=objectID, confirmed=confirmed, lifetime=lifetime
+        )
+        self.this_application.subscription_contexts[
+            context.subscriberProcessIdentifier
+        ] = context
+        return context
+
+    def _build_cov_request(self, context):
+        request = SubscribeCOVRequest(
+            subscriberProcessIdentifier=context.subscriberProcessIdentifier,
+            monitoredObjectIdentifier=context.monitoredObjectIdentifier,
+        )
+        request.pduDestination = context.address
+
+        # optional parameters
+        if context.issueConfirmedNotifications is not None:
+            request.issueConfirmedNotifications = context.issueConfirmedNotifications
+        if context.lifetime is not None:
+            request.lifetime = context.lifetime
+
+        return request
diff --git a/BAC0/scripts/Lite.py b/BAC0/scripts/Lite.py
index eaf0b54b..690546ee 100755
--- a/BAC0/scripts/Lite.py
+++ b/BAC0/scripts/Lite.py
@@ -37,6 +37,7 @@ class ReadWriteScript(BasicScript,ReadProperty,WriteProperty)
 from ..core.functions.TimeSync import TimeSync
 from ..core.functions.Reinitialize import Reinitialize
 from ..core.functions.DeviceCommunicationControl import DeviceCommunicationControl
+from ..core.functions.cov import CoV
 from ..core.io.Simulate import Simulation
 from ..core.devices.Points import Point
 from ..core.devices.Device import RPDeviceConnected, RPMDeviceConnected
@@ -66,6 +67,7 @@ class Lite(
     TimeSync,
     Reinitialize,
     DeviceCommunicationControl,
+    CoV,
 ):
     """
     Build a BACnet application to accept read and write requests.
@@ -76,9 +78,6 @@ class Lite(
     :param ip='127.0.0.1': Address must be in the same subnet as the BACnet network
         [BBMD and Foreign Device - not supported]
 
-    :param bokeh_server: (boolean) If set to false, will prevent Bokeh server
-        from being started. Can help troubleshoot issues with Bokeh. By default,
-        set to True.
     """
 
     def __init__(