Index: dialin/common/msg_defs.py
===================================================================
diff -u -rcff98df963746b055cac8e59ceb899da1903027c -r9e96d02a9333213f5b5c719f15e5884a804b65c8
--- dialin/common/msg_defs.py	(.../msg_defs.py)	(revision cff98df963746b055cac8e59ceb899da1903027c)
+++ dialin/common/msg_defs.py	(.../msg_defs.py)	(revision 9e96d02a9333213f5b5c719f15e5884a804b65c8)
@@ -185,6 +185,7 @@
     MSG_ID_HD_GET_SERVICE_RECORD = 0x8043                       # HD get service record that is requested from Dialin
     MSG_ID_HD_SET_SERVICE_RECORD = 0x8044                       # HD set service record that is received from Dialin
     MSG_ID_HD_SEND_SERVICE_RECORD = 0x8045                      # HD send service record to CAN bus to be received in Dialin (equivalent to publish)
+    MSG_ID_HD_SET_OP_MODE_REQUEST = 0x8046                      # HD set operation mode request
 
     MSG_ID_DG_TESTER_LOGIN_REQUEST = 0XA000                     # DG tester log-in
     MSG_ID_DG_ALARM_STATE_OVERRIDE = 0xA001                     # DG alarm state override message ID
Index: dialin/hd/hemodialysis_device.py
===================================================================
diff -u -r363867c876456821000c189f86fbb55b4d583c50 -r9e96d02a9333213f5b5c719f15e5884a804b65c8
--- dialin/hd/hemodialysis_device.py	(.../hemodialysis_device.py)	(revision 363867c876456821000c189f86fbb55b4d583c50)
+++ dialin/hd/hemodialysis_device.py	(.../hemodialysis_device.py)	(revision 9e96d02a9333213f5b5c719f15e5884a804b65c8)
@@ -51,8 +51,7 @@
     HD_OP_MODE_SERVICE = 1
     HD_OP_MODE_INIT_POST = 2
     HD_OP_MODE_STANDBY = 3
-    HD_OP_MODE_PRESCRIPTION = 4
-    HD_OP_MODE_OP_PARAMS = 5
+    HD_OP_MODE_TREATMENT_PARAMS = 4
     HD_OP_MODE_PRE_TREATMENT = 6
     HD_OP_MODE_TREATMENT = 7
     HD_OP_MODE_POST_TREATMENT = 8
@@ -277,6 +276,48 @@
             self.logger.debug("Timeout!!!!")
             return False
 
+    def cmd_hd_set_operation_mode(self, newMode=0):
+        """
+        Constructs and sends a set operation mode request command via CAN bus.
+        Constraints:
+            Must be logged into HD.
+            Transition from current to requested op mode must be legal.
+
+        @param newMode:  ID of operation mode to transition to
+            HD_OP_MODE_FAULT = 0
+            HD_OP_MODE_SERVICE = 1
+            HD_OP_MODE_INIT_POST = 2
+            HD_OP_MODE_STANDBY = 3
+            HD_OP_MODE_TREATMENT_PARAMS = 4
+            HD_OP_MODE_PRE_TREATMENT = 6
+            HD_OP_MODE_TREATMENT = 7
+            HD_OP_MODE_POST_TREATMENT = 8
+
+        @return: 1 if successful, zero otherwise
+
+        """
+
+        payload = integer_to_bytearray(newMode)
+
+        message = DenaliMessage.build_message(channel_id=DenaliChannels.dialin_to_hd_ch_id,
+                                              message_id=MsgIds.MSG_ID_HD_SET_OP_MODE_REQUEST.value,
+                                              payload=payload)
+
+        self.logger.debug("Requesting HD mode change to " + str(newMode))
+
+        # Send message
+        received_message = self.can_interface.send(message)
+
+        if received_message is not None:
+            if received_message['message'][DenaliMessage.PAYLOAD_START_INDEX] == 1:
+                self.logger.debug("Success: Mode change accepted")
+            else:
+                self.logger.debug("Failure: Mode change rejected.")
+            return received_message['message'][DenaliMessage.PAYLOAD_START_INDEX]
+        else:
+            self.logger.debug("HD mode change request Timeout!!!!")
+            return False
+
     def cmd_hd_safety_shutdown_override(self, active=True, reset=NO_RESET):
         """
         Constructs and sends an HD safety shutdown override command via CAN bus.