Index: firmware/App/Modes/Dialysis.c
===================================================================
diff -u -r11fcffb18d94387a3301eb9ba3cc6bff6e9a5b56 -r1f91b5a53bda942b0967817bbd5e68a499dbf816
--- firmware/App/Modes/Dialysis.c	(.../Dialysis.c)	(revision 11fcffb18d94387a3301eb9ba3cc6bff6e9a5b56)
+++ firmware/App/Modes/Dialysis.c	(.../Dialysis.c)	(revision 1f91b5a53bda942b0967817bbd5e68a499dbf816)
@@ -1,14 +1,14 @@
 /**************************************************************************
 *
-* Copyright (c) 2020-2022 Diality Inc. - All Rights Reserved.
+* Copyright (c) 2020-2023 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    Dialysis.c
 *
-* @author  (last)      Sean Nash
-* @date    (last)      21-Nov-2022
+* @author  (last)      Michael Garthwaite
+* @date    (last)      19-Jan-2023
 *
 * @author  (original)  Sean
 * @date    (original)  15-Jan-2020
@@ -623,6 +623,8 @@
  *************************************************************************/
 void execDialysis( void )
 {
+    DIALYSIS_STATE_T priorSubState = currentDialysisState;
+
     // Check ultrafiltration max rate and accuracy during dialysis (even when ultrafiltration is paused).
     checkUFAccuracyAndVolume();
 
@@ -646,6 +648,10 @@
             break;
     }
 
+    if ( priorSubState != currentDialysisState )
+    {
+        SEND_EVENT_WITH_2_U32_DATA( HD_EVENT_SUB_STATE_CHANGE, priorSubState, currentDialysisState );
+    }
     // Publish saline bolus data at set interval (whether we are delivering one or not)
     publishSalineBolusData();
 }
@@ -661,6 +667,7 @@
 static DIALYSIS_STATE_T handleDialysisUltrafiltrationState( void )
 {
     DIALYSIS_STATE_T result = DIALYSIS_UF_STATE;
+    UF_STATE_T priorSubState = currentUFState;
     U32 preStop = getTreatmentParameterU32( TREATMENT_PARAM_HEPARIN_PRE_STOP_TIME );
     F32 minRem  = (F32)getTreatmentTimeRemainingSecs() / (F32)SEC_PER_MIN;
 
@@ -697,6 +704,11 @@
             break;
     }
 
+    if ( priorSubState != currentUFState )
+    {
+        SEND_EVENT_WITH_2_U32_DATA( HD_EVENT_SUB_STATE_CHANGE, priorSubState, currentUFState );
+    }
+
     return result;
 }
 
@@ -712,6 +724,8 @@
 {
     DIALYSIS_STATE_T result = DIALYSIS_SALINE_BOLUS_STATE;
 
+    SALINE_BOLUS_STATE_T priorSubState = currentSalineBolusState;
+
     switch ( currentSalineBolusState )
     {
         case SALINE_BOLUS_STATE_IDLE:
@@ -736,6 +750,11 @@
             break;
     }
 
+    if ( priorSubState != currentSalineBolusState )
+    {
+        SEND_EVENT_WITH_2_U32_DATA( HD_EVENT_SUB_STATE_CHANGE, priorSubState, currentSalineBolusState );
+    }
+
     return result;
 }