Index: DDDefs.h
===================================================================
diff -u -r0fafac8c92a5f9dd4b65fd566f613dfae2537106 -r2f1fb9398dd362ca53314154294c6a5653f37a2b
--- DDDefs.h	(.../DDDefs.h)	(revision 0fafac8c92a5f9dd4b65fd566f613dfae2537106)
+++ DDDefs.h	(.../DDDefs.h)	(revision 2f1fb9398dd362ca53314154294c6a5653f37a2b)
@@ -367,13 +367,14 @@
     D40_VALV,                                     ///< Valve Dialyzer Outlet (D40)
     D47_VALV,                                     ///< Valve Dialysate Out Purge 2 (D47)
     D3_VALV,                                      ///< Valve Hydraulics Inlet (D3)
-    M4_VALV,                                      ///< Valve Water Inlet (M4)
+    // For standalone DD system, may need to control IO valve.
+    DD_M4_VALV,                                   ///< Valve Water Inlet (M4)
 #ifdef __PUMPTEST__
     UF1,                                          ///< UF1 valve
     UF2,                                          ///< UF2 valve
     LAST_HYD_VALVE = UF2,                         ///< End of Hydraulics valve of group
 #else
-    LAST_HYD_VALVE = M4_VALV,                     ///< End of Hydraulics valve of group
+    LAST_HYD_VALVE = DD_M4_VALV,                  ///< End of Hydraulics valve of group
     RSRVD_SPACE1,                                 ///< This space has been reserved
     RSRVD_SPACE2,                                 ///< This space has been reserved
 #endif