Index: MsgDefs.h
===================================================================
diff -u -r5665412d80f6a4690ed054eb744cee173d3e5a14 -r099ccd3d956cd529b4282350d0bff998ea10ec38
--- MsgDefs.h	(.../MsgDefs.h)	(revision 5665412d80f6a4690ed054eb744cee173d3e5a14)
+++ MsgDefs.h	(.../MsgDefs.h)	(revision 099ccd3d956cd529b4282350d0bff998ea10ec38)
@@ -8,8 +8,8 @@
 *
 * @file    MsgDefs.h
 *
-* @author  (last)      Praneeth Bunne
-* @date    (last)      21-May-2026
+* @author  (last)      Dara Navaei
+* @date    (last)      27-May-2026
 *
 * @author  (original)  Sean Nash
 * @date    (original)  01-Aug-2024
@@ -208,6 +208,8 @@
     MSG_ID_TD_TUBE_SET_AUTHENTICATION_ACK_RESPONSE = 0xB0,                          ///< TD tube set authentication acknowledge response
     MSG_ID_TD_SYRINGE_PUMP_DATA = 0xB1,                                             ///< TD broadcast of syringe pump data
     MSG_ID_TD_HEPARIN_PAUSE_RESUME_RESPONSE= 0xB2,                                  ///< TD response to pause/resume Heparin delivery request
+    MSG_ID_FFU_SIGNAL_TD_UPDATE_AVAILABLE = 0xB3,                                   ///< FFU signal TD update is available.
+    MSG_ID_FFU_SIGNAL_DD_UPDATE_AVAILABLE = 0xB4,                                   ///< FFU signal DD update is available.
 
     // service/test CAN messages
     MSG_ID_FIRST_TD_TESTER_MESSAGE = 0x8000,                                        ///< First TD test message ID
Index: TDDefs.h
===================================================================
diff -u -r6acee1b50587f2c08c433b52fd518c9a83b8b43c -r099ccd3d956cd529b4282350d0bff998ea10ec38
--- TDDefs.h	(.../TDDefs.h)	(revision 6acee1b50587f2c08c433b52fd518c9a83b8b43c)
+++ TDDefs.h	(.../TDDefs.h)	(revision 099ccd3d956cd529b4282350d0bff998ea10ec38)
@@ -7,8 +7,8 @@
 *
 * @file    TDDefs.h
 *
-* @author  (last)      Praneeth Bunne
-* @date    (last)      21-May-2026
+* @author  (last)      Dara Navaei
+* @date    (last)      27-May-2026
 *
 * @author  (original)  Sean Nash
 * @date    (original)  01-Aug-2024
@@ -35,6 +35,7 @@
     MODE_PRET,                           ///< Pre-Treatment mode
     MODE_TREA,                           ///< Treatment mode
     MODE_POST,                           ///< Post-Treatment mode
+    MODE_UPDT,                           ///< Update mode
     MODE_NLEG,                           ///< Not legal - an illegal mode transition occurred
     NUM_OF_MODES                         ///< Number of TD operation modes
 };
@@ -113,6 +114,22 @@
 /**@}*/
 
 /**
+ *  @addtogroup TDUpdateMode
+ *  @{
+ */
+
+/// Sub-mode states while in update mode
+enum TD_Update_States
+{
+    TD_UPDATE_INIT_STATE = 0,                                    ///< Start update state.
+    TD_UPDATE_RESET_MCU_STATE,                                   ///< Reset MCU state.
+    NUM_OF_TD_UPDATE_STATES                                      ///< Number of update states (sub-modes).
+};
+typedef enum TD_Update_States TD_UPDATE_STATE_T;                 ///< Type for TD update states enumeration
+
+/**@}*/
+
+/**
  *  @addtogroup TDPreTreatmentMode
  *  @{
  */