Index: firmware/App/Modes/TreatmentStop.c
===================================================================
diff -u -r89fb8ae8b3e451cb37ccd05b6ba9b92e89820f35 -r6b870cd0699bb3ee22b93981d51373a6c2d56162
--- firmware/App/Modes/TreatmentStop.c	(.../TreatmentStop.c)	(revision 89fb8ae8b3e451cb37ccd05b6ba9b92e89820f35)
+++ firmware/App/Modes/TreatmentStop.c	(.../TreatmentStop.c)	(revision 6b870cd0699bb3ee22b93981d51373a6c2d56162)
@@ -22,6 +22,7 @@
 #include "DialOutFlow.h"
 #include "ModeTreatment.h"
 #include "OperationModes.h"
+#include "TaskGeneral.h"
 #include "TreatmentStop.h"
 #include "Valves.h"
 
@@ -30,9 +31,15 @@
  *  @{
  */
 
+// ********** private definitions **********
+
+/// Maximum time in this mode before blood sitting warning given (in general task intervals).
+static const U32 MAX_TIME_BLOOD_SITTING = ( ( 5 * SEC_PER_MIN * MS_PER_SECOND ) / TASK_GENERAL_INTERVAL );
+
 // ********** private data **********
 
 static TREATMENT_STOP_STATE_T currentTxStopState;                                  ///< Current treatment stop state.
+static U32 bloodSittingTimerCtr;                                                   ///< Timer counter tracks time in this mode while blood is sitting.
 
 // ********** private function prototypes **********
 
@@ -50,6 +57,7 @@
 void initTreatmentStop( void )
 {
     currentTxStopState = TREATMENT_STOP_RECIRC_STATE;
+    bloodSittingTimerCtr = 0;
 }
 
 /*********************************************************************//**
@@ -124,6 +132,13 @@
  *************************************************************************/
 void execTreatmentStop( void )
 {
+    // Ensure we do not sit in stopped state for too long
+    if ( ++bloodSittingTimerCtr > MAX_TIME_BLOOD_SITTING )
+    {
+        activateAlarmNoData( ALARM_ID_BLOOD_SITTING_TOO_LONG_NO_RINSEBACK );
+    }
+
+    // Execute treatment stop sub-mode state machine
     switch ( currentTxStopState )
     {
         case TREATMENT_STOP_RECIRC_STATE: