Index: firmware/App/Controllers/DGInterface.c
===================================================================
diff -u -r1a685471524555a374854c0c9ec8e208e71fe2df -r85ab84d9a0668e1e3976b00eb29e79c38c81b651
--- firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision 1a685471524555a374854c0c9ec8e208e71fe2df)
+++ firmware/App/Controllers/DGInterface.c	(.../DGInterface.c)	(revision 85ab84d9a0668e1e3976b00eb29e79c38c81b651)
@@ -83,7 +83,8 @@
 static U32 dgReservoirDrainVolumeTarget = 0;                    ///< Latest drain-to volume reported by the DG.
 static U32 dgReservoirDrainVolumeTargetSet = 0;                 ///< Drain-to volume commanded.
 static U32 resUseTimer = 0;                                     ///< used to track time pumping from active reservoir (for volume used calculation).
-static F32 resUseVolumeMl = 0.0;                                  ///< Accumulated volume used from active reservoir.
+static F32 resUseVolumeMl = 0.0;                                ///< Accumulated volume used from active reservoir.
+static BOOL resHasBeenTared[ NUM_OF_DG_RESERVOIRS ];            ///< Flags indicate whether the reservoir has been tared for this treatment.
 
 // ********** private function prototypes **********
 
@@ -104,9 +105,26 @@
     dgTrimmerTempSet = 0.0;
     dgActiveReservoirSet = DG_RESERVOIR_2;
     dgReservoirFillVolumeTargetSet = 0;
-    dgReservoirDrainVolumeTargetSet = 0;
+    dgReservoirDrainVolumeTargetSet = 0;
+    initPreTreatmentReservoirMgmt();
 }
 
+/*********************************************************************//**
+ * @brief
+ * The initPreTreatmentReservoirMgmt function initializes the pre-treatment
+ * reservoir management state machine.
+ * @details Inputs: none
+ * @details Outputs: pre-treatment reservoir management state machine initialized.
+ * @return none
+ *************************************************************************/
+void initPreTreatmentReservoirMgmt( void )
+{
+    // TODO - currentPreTrtResMgmtState = TREATMENT_RESERVOIR_MGMT_START_STATE;
+    resMgmtTimer = 0;
+    resHasBeenTared[ DG_RESERVOIR_1 ] = FALSE;
+    resHasBeenTared[ DG_RESERVOIR_2 ] = FALSE;
+}
+
 /*********************************************************************//**
  * @brief
  * The initTreatmentReservoirMgmt function initializes the treatment reservoir
@@ -123,6 +141,18 @@
     resUseVolumeMl = 0.0;
 }
 
+/*********************************************************************//**
+ * @brief
+ * The execPreTreatmentReservoirMgmt function executes the state machine for the
+ * reservoir management during pre-treatment mode.
+ * @details Inputs: none
+ * @details Outputs: DG reservoirs (drains & fills) managed.
+ * @return none
+ *************************************************************************/
+void execPreTreatmentReservoirMgmt( void )
+{
+}
+
 /*********************************************************************//**
  * @brief
  * The execTreatmentReservoirMgmt function executes the state machine for the
@@ -289,6 +319,20 @@
     return dgActiveReservoirSet;
 }
 
+/*********************************************************************//**
+ * @brief
+ * The getDGInactiveReservoir function gets the currently inactive reservoir.
+ * @details Inputs: dgActiveReservoirSet
+ * @details Outputs: none
+ * @return Currently commanded inactive reservoir.
+ *************************************************************************/
+DG_RESERVOIR_ID_T getDGInactiveReservoir( void )
+{
+    DG_RESERVOIR_ID_T inactiveRes = ( DG_RESERVOIR_2 == dgActiveReservoirSet ? DG_RESERVOIR_1 : DG_RESERVOIR_2 );
+
+    return inactiveRes;
+}
+
 /*********************************************************************//**
  * @brief
  * The getDGPressure function gets the latest pressure reported by the DG
@@ -600,13 +644,18 @@
  * The cmdStartDGDrain function sends a drain command message to the DG.
  * @details Inputs: none
  * @details Outputs: drain command sent to DG.
- * @param drainToVolMl volume (in mL) to drain inactive reservoir to
+ * @param drainToVolMl volume (in mL) to drain inactive reservoir to
  * @return none
  *************************************************************************/
 void cmdStartDGDrain( U32 drainToVolMl )
-{
-    dgReservoirDrainVolumeTargetSet = drainToVolMl;
-    sendDGDrainCommand( drainToVolMl );
+{
+    DRAIN_RESERVOIR_CMD_PAYLOAD_T payload;
+    DG_RESERVOIR_ID_T inactiveRes = getDGInactiveReservoir();
+
+    dgReservoirDrainVolumeTargetSet = drainToVolMl;
+    payload.drainToVolumeML = drainToVolMl;
+    payload.tareLoadCells = ( FALSE == resHasBeenTared[ inactiveRes ] ? TRUE : FALSE );
+    sendDGDrainCommand( &payload );
 }
 
 /*********************************************************************//**