Index: firmware/App/Controllers/HemoDiaFiltration.h
===================================================================
diff -u -rfc697848283d289571f9d365b28acf44beb0883e -rfff7eb3560421130e0cd4788f84bce0a8ee7ff44
--- firmware/App/Controllers/HemoDiaFiltration.h	(.../HemoDiaFiltration.h)	(revision fc697848283d289571f9d365b28acf44beb0883e)
+++ firmware/App/Controllers/HemoDiaFiltration.h	(.../HemoDiaFiltration.h)	(revision fff7eb3560421130e0cd4788f84bce0a8ee7ff44)
@@ -31,31 +31,53 @@
 
 // ********** public definitions **********
 
+#define HDF_MAX_FILTRATION_FRACTION             0.35F                                             ///< HDF maximum filtration fraction (Qs+Quf)/Qb
+#define HDF_MAX_TMP                             400.0F                                            ///< HDF maximum TMP - trans-membrane pressure = (Pb - Pd)
+#define HDF_MAX_RATE                            200.0F                                            ///< Maximum substitution flow rate
+
+/// hemodiafiltration states
+typedef enum
+{
+    TD_HDF_PAUSED,                                                      ///< HDF Paused
+    TD_HDF_RUNNING,                                                     ///< HDF Running
+    NUM_OF_TD_HDF_STATES,
+} HDF_EXEC_STATE_T;
+
 /// hemodiafiltration data structure
 typedef struct
 {
-    U32 hdfExecState;                                                    ///< Hemodiafiltration execution state
-    F32 hdfRequestedRate;                                                ///< Hemodiafiltration requested manual rate
-    F32 hdfTargetTMP;                                                    ///< Hemodiafiltration requested target TMP
-    F32 hdfCurrentRate;                                                  ///< Hemodiafiltration current set rate
-    F32 hdfCurrentTMP;                                                   ///< Hemodiafiltration current TMP (trans-membrane pressure)
-    F32 hdfRequestedVolume;                                              ///< Hemodiafiltration requested maximum volume
-    F32 hdfTotalVolume;                                                  ///< Hemodiafiltration total volume delivered
-    U32 isHDFRequested;                                                  ///< Hemodiafiltration run or pause request
+    U32 hdfExecState;                                                   ///< Hemodiafiltration execution state
+    F32 hdfRequestedRate;                                               ///< Hemodiafiltration requested manual rate
+    F32 hdfTargetTMP;                                                   ///< Hemodiafiltration requested target TMP
+    F32 hdfCurrentRate;                                                 ///< Hemodiafiltration current set rate
+    F32 hdfCurrentTMP;                                                  ///< Hemodiafiltration current TMP (trans-membrane pressure)
+    F32 hdfRequestedVolume;                                             ///< Hemodiafiltration requested maximum volume
+    F32 hdfTotalVolume;                                                 ///< Hemodiafiltration total volume delivered
+    U32 isHDFRequested;                                                 ///< Hemodiafiltration run or pause request
 } HDF_DATA_T;
 
+typedef struct
+{
+    U32 hdfStart;                                                       ///< HDF start stop boolean.
+    F32 hdfTMPTgt;                                                      ///< HDF target pressure to control.
+    F32 hdfVolume;                                                      ///< HDF Target volume.
+    F32 hdfRate;                                                        ///< HDF open loop rate.
+} HDF_START_PAYLOAD_T;
+
 // ********** public function prototypes **********
 
-void initHemodiafiltration( void );                                        // Initialize hemodiafiltration unit
-void transitionToHemodiafiltration( void );                                // Prepares for transition to hemodiafiltration execution
-U32 execHDFControl( void );                                               // Execute the hemodiafiltration state machine
-HDF_EXEC_STATE_T getCurrentHDFExecState( void );                           // Get the current state of the hemodifiltration execution
+void initHemodiafiltration( void );                                     // Initialize hemodiafiltration unit
+void transitionToHemodiafiltration( void );                             // Prepares for transition to hemodiafiltration execution
+U32 execHDFControl( void );                                             // Execute the hemodiafiltration state machine
+HDF_EXEC_STATE_T getCurrentHDFExecState( void );                        // Get the current state of the hemodifiltration execution
+F32 getCurrentHDFRate( void );
 
-BOOL testTDHDFDataPublishIntervalOverride( MESSAGE_T *message );          // To override the HDF data publish interval
-void setHemodiafiltrationParameters( F32 setHDFTMPTarget, F32 setHDFManualRate,  F32 setHDFMaximumVolume);
+void setHemodiafiltrationParameters( F32 setHDFTMPTarget, F32 setHDFMaximumVolume);
+void setHemoDiafiltrationManualRate( F32 setHDFManualRate );
 void StartHemodiafiltration( void );
 void StopHemodiafiltration( void );
 
+BOOL testTDHDFDataPublishIntervalOverride( MESSAGE_T *message );          // To override the HDF data publish interval
 /**@}*/
 
 #endif