Index: firmware/App/Modes/Dialysis.c
===================================================================
diff -u -r49533d4870aa10c1b20406dd5c013567fe854694 -r7cf04dc00d1242aba62f3cd4e4bcb19f1e83ebc6
--- firmware/App/Modes/Dialysis.c	(.../Dialysis.c)	(revision 49533d4870aa10c1b20406dd5c013567fe854694)
+++ firmware/App/Modes/Dialysis.c	(.../Dialysis.c)	(revision 7cf04dc00d1242aba62f3cd4e4bcb19f1e83ebc6)
@@ -106,6 +106,7 @@
 static void updateUFVolumes( void );
 
 static void publishSalineBolusData( void );
+static void checkLoadCellsStablePrimaryBackupDriftOutOfRange( DG_RESERVOIR_ID_T reservoirID, BOOL reservoirFull );
 
 /*********************************************************************//**
  * @brief
@@ -1135,6 +1136,8 @@
     // Set starting baseline volume for next reservoir before we switch to it
     resStartVolume[ reservoirID ] = resVolume;
     resFinalVolume[ reservoirID ] = resVolume;
+
+    checkLoadCellsStablePrimaryBackupDriftOutOfRange( reservoirID, false );
 }
 
 /*********************************************************************//**
@@ -1172,6 +1175,8 @@
     measUFVolumeFromPriorReservoirs -= ( resFinalVolume[ inactiveRes ] - resStartVolume[ inactiveRes ] );
     resFinalVolume[ inactiveRes ] = resVolume;
     measUFVolumeFromPriorReservoirs += ( resFinalVolume[ inactiveRes ] - resStartVolume[ inactiveRes ] );
+
+    checkLoadCellsStablePrimaryBackupDriftOutOfRange( inactiveRes, true );
 }
 
 /*********************************************************************//**
@@ -1206,4 +1211,109 @@
     return ( resFinalVolume[ reservoirID ] - resStartVolume[ reservoirID ] );
 }
 
+/*********************************************************************//**
+ * @brief
+ * The checkLoadCellsStablePrimaryBackupDriftOutOfRange function checks the
+ * load cells' primary and backup drift when the reservoir level has been stable
+ * for greater than large filter time.
+ * @details Inputs: none
+ * @details Outputs: none
+ * @param reservoirID which is the reservoir ID that is range checked
+ * @param reservoirFull is the reservoir status full or empty
+ * @return none
+ *************************************************************************/
+#define LOAD_CELL_ILLEGAL_WEIGHT_VALUE     -1000.0F
+static void checkLoadCellsStablePrimaryBackupDriftOutOfRange( DG_RESERVOIR_ID_T reservoirID, BOOL reservoirFull )
+{
+    static F32 lastEmptyWeight[NUM_OF_LOAD_CELLS] = { LOAD_CELL_ILLEGAL_WEIGHT_VALUE,
+                                                      LOAD_CELL_ILLEGAL_WEIGHT_VALUE,
+                                                      LOAD_CELL_ILLEGAL_WEIGHT_VALUE,
+                                                      LOAD_CELL_ILLEGAL_WEIGHT_VALUE };
+    static F32 lastFullWeight[NUM_OF_LOAD_CELLS]  = { LOAD_CELL_ILLEGAL_WEIGHT_VALUE,
+                                                      LOAD_CELL_ILLEGAL_WEIGHT_VALUE,
+                                                      LOAD_CELL_ILLEGAL_WEIGHT_VALUE,
+                                                      LOAD_CELL_ILLEGAL_WEIGHT_VALUE };
+    F32 loadCellPrimaryWeight, loadCellBackupWeight;
+    F32 loadCellPreviousDrift, loadCellCurrentDrift;
+    F32 driftDiff = 0.0;
+
+    if ( reservoirID == DG_RESERVOIR_1 )
+    {
+        // Reservoir 1
+        loadCellPrimaryWeight = getReservoirWeightLargeFilter( DG_RESERVOIR_1 );
+        loadCellBackupWeight  = getReservoirBackupWeightLargeFilter( DG_RESERVOIR_1 );
+        loadCellCurrentDrift = fabs( loadCellPrimaryWeight - loadCellBackupWeight );
+
+        if ( reservoirFull )
+        {
+            if ( lastFullWeight[LOAD_CELL_RESERVOIR_1_PRIMARY] > (LOAD_CELL_ILLEGAL_WEIGHT_VALUE + 1) )
+            {
+                // Weight has been previously saved, ok to test
+                loadCellPreviousDrift = fabs( lastFullWeight[LOAD_CELL_RESERVOIR_1_PRIMARY] -
+                                              lastFullWeight[LOAD_CELL_RESERVOIR_1_BACKUP] );
+                driftDiff = fabs ( loadCellCurrentDrift - loadCellPreviousDrift );
+            }
+            // Save latest reading for next test time
+            lastFullWeight[LOAD_CELL_RESERVOIR_1_PRIMARY] = loadCellPrimaryWeight;
+            lastFullWeight[LOAD_CELL_RESERVOIR_1_BACKUP]  = loadCellBackupWeight;
+        }
+        else
+        {
+            if ( lastEmptyWeight[LOAD_CELL_RESERVOIR_1_PRIMARY] > (LOAD_CELL_ILLEGAL_WEIGHT_VALUE + 1) )
+            {
+                // Weight has been previously saved, ok to test
+                loadCellPreviousDrift = fabs( lastEmptyWeight[LOAD_CELL_RESERVOIR_1_PRIMARY] -
+                                              lastEmptyWeight[LOAD_CELL_RESERVOIR_1_BACKUP] );
+                driftDiff = fabs ( loadCellCurrentDrift - loadCellPreviousDrift );
+            }
+            // Save latest reading for next test time
+            lastEmptyWeight[LOAD_CELL_RESERVOIR_1_PRIMARY] = loadCellPrimaryWeight;
+            lastEmptyWeight[LOAD_CELL_RESERVOIR_1_BACKUP]  = loadCellBackupWeight;
+        }
+    }
+    else
+    {
+        // Reservoir 2
+        loadCellPrimaryWeight = getReservoirWeightLargeFilter( DG_RESERVOIR_2 );
+        loadCellBackupWeight  = getReservoirBackupWeightLargeFilter( DG_RESERVOIR_2 );
+        loadCellCurrentDrift = fabs( loadCellPrimaryWeight - loadCellBackupWeight );
+
+        if ( reservoirFull )
+        {
+            if ( lastFullWeight[LOAD_CELL_RESERVOIR_2_PRIMARY] > (LOAD_CELL_ILLEGAL_WEIGHT_VALUE + 1) )
+            {
+                // Weight has been previously saved, ok to test
+                loadCellPreviousDrift = fabs( lastFullWeight[LOAD_CELL_RESERVOIR_2_PRIMARY] -
+                                              lastFullWeight[LOAD_CELL_RESERVOIR_2_BACKUP] );
+                driftDiff = fabs ( loadCellCurrentDrift - loadCellPreviousDrift );
+            }
+            // Save latest reading for next test time
+            lastFullWeight[LOAD_CELL_RESERVOIR_2_PRIMARY] = loadCellPrimaryWeight;
+            lastFullWeight[LOAD_CELL_RESERVOIR_2_BACKUP]  = loadCellBackupWeight;
+        }
+        else
+        {
+            if ( lastEmptyWeight[LOAD_CELL_RESERVOIR_2_PRIMARY] > (LOAD_CELL_ILLEGAL_WEIGHT_VALUE + 1) )
+            {
+                // Weight has been previously saved, ok to test
+                loadCellPreviousDrift = fabs( lastEmptyWeight[LOAD_CELL_RESERVOIR_2_PRIMARY] -
+                                              lastEmptyWeight[LOAD_CELL_RESERVOIR_2_BACKUP] );
+                driftDiff = fabs ( loadCellCurrentDrift - loadCellPreviousDrift );
+            }
+            // Save latest reading for next test time
+            lastEmptyWeight[LOAD_CELL_RESERVOIR_2_PRIMARY] = loadCellPrimaryWeight;
+            lastEmptyWeight[LOAD_CELL_RESERVOIR_2_BACKUP]  = loadCellBackupWeight;
+        }
+    }
+
+    // TODO Set proper limits and use separate Alarm Number
+    if ( driftDiff > LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS )
+    {
+        //checkPersistentAlarm( ALARM_ID_DG_LOAD_CELL_PRIMARY_BACKUP_DRIFT_OUT_OF_RANGE, isDriftOutOfRange, driftDiff,
+        //                      LOAD_CELL_PRIMARY_BACKUP_MAX_ALLOWED_DRIFT_GRAMS );
+        SET_ALARM_WITH_2_F32_DATA( ALARM_ID_DG_LOAD_CELL_PRIMARY_BACKUP_DRIFT_OUT_OF_RANGE, loadCellCurrentDrift, loadCellPreviousDrift )
+    }
+}
+
+
 /**@}*/