Index: dialin/common/msg_ids.py
===================================================================
diff -u -r410627f2a7a611e5c8c0115a1dafaed44e4df57b -r39a6a491a48545b1dd6c39a72a13d8ca55f941cf
--- dialin/common/msg_ids.py	(.../msg_ids.py)	(revision 410627f2a7a611e5c8c0115a1dafaed44e4df57b)
+++ dialin/common/msg_ids.py	(.../msg_ids.py)	(revision 39a6a491a48545b1dd6c39a72a13d8ca55f941cf)
@@ -396,6 +396,7 @@
     MSG_ID_DG_SET_SW_CONFIG_RECORD = 0xA04B
     MSG_ID_DG_SEND_SW_CONFIG_RECORD = 0xA04C
     MSG_ID_DG_FANS_DUTY_CYCLE_OVERRIDE = 0xA04D
+    MSG_ID_DG_HD_COMMUNICATION_STATUS_OVERRIDE = 0xA04E
 
     MSG_ID_HD_DEBUG_EVENT = 0xFFF1
     MSG_ID_DG_DEBUG_EVENT = 0xFFF2
Index: dialin/dg/hd_proxy.py
===================================================================
diff -u -r3a70bfb451b74106348c064c34f19934aadd9119 -r39a6a491a48545b1dd6c39a72a13d8ca55f941cf
--- dialin/dg/hd_proxy.py	(.../hd_proxy.py)	(revision 3a70bfb451b74106348c064c34f19934aadd9119)
+++ dialin/dg/hd_proxy.py	(.../hd_proxy.py)	(revision 39a6a491a48545b1dd6c39a72a13d8ca55f941cf)
@@ -19,6 +19,7 @@
 from ..protocols.CAN import DenaliMessage, DenaliChannels
 from ..utils.base import AbstractSubSystem
 from ..utils.conversions import integer_to_bytearray, float_to_bytearray
+from ..dg import NO_RESET, RESET
 
 
 class DGHDProxy(AbstractSubSystem):
@@ -333,3 +334,40 @@
         else:
             self.logger.debug("Timeout!!!!")
             return False
+
+    def cmd_hd_communication_status_override(self, reset: int = NO_RESET) -> int:
+        """
+        Constructs and sends the HD communication status override command.
+        Constraints:
+            Must be logged into DG.
+
+        Method only sets HD Communication status to True on NO_RESET. Therefore, when this message
+        is called when the HD and DG are communicating, there will be no noticeable effect.
+
+        @param reset:  integer - 1 to reset a previous override, 0 to override
+        @return: 1 if successful, zero otherwise
+        """
+        reset_byte_array = integer_to_bytearray(reset)
+        payload = reset_byte_array
+
+        message = DenaliMessage.build_message(channel_id=DenaliChannels.dialin_to_dg_ch_id,
+                                              message_id=MsgIds.MSG_ID_DG_HD_COMMUNICATION_OVERRIDE.value,
+                                              payload=payload)
+
+        self.logger.debug("Overriding DG HD communication Status.")
+        # Send message
+        received_message = self.can_interface.send(message)
+
+        # If there is content...
+        if received_message is not None:
+            if reset == RESET:
+                str_res = "Reset "
+            else:
+                str_res = "Set "
+            self.logger.debug("HD Communication status overridden to " + str_res +
+                              str(received_message['message'][DenaliMessage.PAYLOAD_START_INDEX]))
+            # response payload is OK or not OK
+            return received_message['message'][DenaliMessage.PAYLOAD_START_INDEX]
+        else:
+            self.logger.debug("Timeout!!!!")
+            return False
\ No newline at end of file
Index: dialin/hd/post_treatment.py
===================================================================
diff -u
--- dialin/hd/post_treatment.py	(revision 0)
+++ dialin/hd/post_treatment.py	(revision 39a6a491a48545b1dd6c39a72a13d8ca55f941cf)
@@ -0,0 +1,62 @@
+###########################################################################
+#
+# Copyright (c) 2020-2022 Diality Inc. - All Rights Reserved.
+#
+# THIS CODE MAY NOT BE COPIED OR REPRODUCED IN ANY FORM, IN PART OR IN
+# WHOLE, WITHOUT THE EXPLICIT PERMISSION OF THE COPYRIGHT OWNER.
+#
+# @file    post_treatment.py
+#
+# @author  (last)      Michael Garthwaite
+# @date    (last)      22-Feb-2022
+# @author  (original)  Michael Garthwaite
+# @date    (original)  22-Feb-2022
+#
+############################################################################
+import struct
+from logging import Logger
+
+from ..common.msg_defs import MsgIds, MsgFieldPositions
+from ..protocols.CAN import DenaliChannels
+from ..utils.base import AbstractSubSystem, publish
+
+
+class HDPostTreatment(AbstractSubSystem):
+    """
+
+    Hemodialysis Delivery (HD) Dialin API sub-class for post treatment related commands.
+
+    """
+
+    def __init__(self, can_interface, logger: Logger):
+        """
+        HDPostTreatment constructor
+        """
+
+        super().__init__()
+        self.can_interface = can_interface
+        self.logger = logger
+
+        if self.can_interface is not None:
+            self.can_interface.register_receiving_publication_function(DenaliChannels.hd_sync_broadcast_ch_id,
+                                                                       MsgIds.MSG_ID_HD_POST_TREATMENT_STATE.value,
+                                                                       self._handler_post_treatment_sub_mode_sync)
+
+        self.post_treatment_sub_mode = 0
+
+    def get_post_treatment_sub_mode(self) -> int:
+        """
+        Returns post treatment submode (in int)
+        """
+        return self.post_treatment_sub_mode
+
+    @publish(["post_treatment_sub_mode"])
+    def _handler_post_treatment_sub_mode_sync(self, message):
+        """
+        Handles published post treatment sub mode data messages. Sub mode data is also captured for reference.
+
+        @param message:  published post treatment sub mode broadcast message
+        @return: none
+        """
+        self.post_treatment_sub_mode = struct.unpack('<I', bytearray(
+            message['message'][MsgFieldPositions.START_POS_FIELD_1:MsgFieldPositions.END_POS_FIELD_1]))[0]