Index: leahi_dialin/fp/proxies/dd_proxy.py
===================================================================
diff -u -r68422d08c4141999a13496343264483a32314d37 -r89bc63999a581c9bf99c68f20ad05b30b6dcf0cb
--- leahi_dialin/fp/proxies/dd_proxy.py	(.../dd_proxy.py)	(revision 68422d08c4141999a13496343264483a32314d37)
+++ leahi_dialin/fp/proxies/dd_proxy.py	(.../dd_proxy.py)	(revision 89bc63999a581c9bf99c68f20ad05b30b6dcf0cb)
@@ -13,28 +13,30 @@
 # @date    (original)  02-Apr-2020
 #
 ############################################################################
-import struct
+
 from logging import Logger
 
-from leahi_dialin.common.msg_defs import MsgIds, MsgFieldPositions
+from leahi_dialin.common.msg_defs import MsgIds
+from leahi_dialin.common.fp_defs import FPOpModes
 from leahi_dialin.protocols.CAN import DenaliMessage, DenaliCanMessenger, DenaliChannels
-from leahi_dialin.utils.base import AbstractSubSystem, publish
-from leahi_dialin.utils.conversions import integer_to_bytearray, byte_to_bytearray, float_to_bytearray
+from leahi_dialin.utils.base import AbstractSubSystem
+from leahi_dialin.utils.conversions import integer_to_bytearray, float_to_bytearray
 
 
 class DDProxy(AbstractSubSystem):
     """
     Filtration Purification (FP) Dialin API sub-class for DD proxy ( injection ) related commands.
     """
 
-    def __init__(self, can_interface: DenaliCanMessenger, logger: Logger):
+    def __init__(self, can_interface: DenaliCanMessenger, logger: Logger, fp):
         """
         ROProxy constructor
 
         @param can_interface: the Denali CAN interface object
         """
 
         super().__init__()
+        self._fp = fp
         self.can_interface = can_interface
         self.logger = logger
 
@@ -60,3 +62,24 @@
         self.logger.debug("Sending DD start stop request to FP.")
         self.can_interface.send(message, 0)
 
+
+    def cmd_send_dd_mode_change_request(self, op_mode: int) -> int:
+        """
+        Constructs and sends a set operation mode request command via internal CAN bus.
+        Constraints:
+            Must be logged into FP.
+            Transition from current to requested op mode must be legal.
+            NOTE: for POST the FP device shall be in Standby Mode
+
+        @param op_mode: ID of operation mode to transition to
+
+        @return: 1 if successful, zero otherwise
+        """
+
+        target_opmode = op_mode
+        if op_mode in [FPOpModes.MODE_PRE_GENP, FPOpModes.MODE_DPGP]:
+            target_opmode = FPOpModes.MODE_DPGP if self._fp.fp_defeaturized else FPOpModes.MODE_PRE_GENP
+        elif op_mode in [FPOpModes.MODE_GENP, FPOpModes.MODE_DEGP]:
+            target_opmode = FPOpModes.MODE_DEGP if self._fp.fp_defeaturized else FPOpModes.MODE_GENP
+
+        return self._fp.cmd_fp_set_operation_mode(target_opmode)