diff --git a/ess/lib_tw_elem.py b/ess/lib_tw_elem.py
index e8b208664d18bc73555b9af72ef585a749193f74..7ff762c82333e53215ac4a2c5ce467a79ebaa7db 100644
--- a/ess/lib_tw_elem.py
+++ b/ess/lib_tw_elem.py
@@ -29,9 +29,23 @@
 
       * Passive commands
 
+        ADJUST      
         FREQ
         MARKER
 
+      * Error commands (active)
+
+        ERROR_BEAM_STAT
+        ERROR_BEAM_DYN
+        ERROR_QUAD_NCPL_STAT
+        ERROR_QUAD_CPL_STAT
+        ERROR_CAV_NCPL_STAT
+        ERROR_CAV_NCPL_DYN
+        ERROR_CAV_CPL_STAT
+        ERROR_CAV_CPL_DYN
+        ERROR_STAT_FILE
+        ERROR_DYN_FILE
+        
       * Other commands for just common "COMM"
 
         END
@@ -49,13 +63,6 @@
         MIN_PHASE_VARIATION
         START_ACHROMAT
 
-        ERROR_QUAD_NCPL_STAT
-        ERROR_QUAD_CPL_STAT
-        ERROR_CAV_NCPL_STAT
-        ERROR_CAV_NCPL_DYN
-        ERROR_CAV_CPL_STAT
-        ERROR_CAV_CPL_DYN
-        ADJUST
         ADJUST_STEERER
         ADJUST_STEERER_BX
         ADJUST_STEERER_BY
@@ -77,8 +84,14 @@
       * 2016.08.18
 
         - Asymmetric aperture of DRIFT implemented.
+
+      * 2017.01.03
+
+        - ERROR_STAT/DYN_FILE implemented.     
 '''
 
+#---- Initial
+
 from __future__ import print_function
 
 #---- Libs
@@ -1062,7 +1075,6 @@ class MARKER(COMM):
 
 class ADJUST(COMM):
     '''
-        - Uncommented for THIN_STEERING.
     '''
     def __init__(self,name,typ,para):
 
@@ -1339,4 +1351,38 @@ class ERROR_CAV_CPL_DYN(ERROR_CAV):
 
         ERROR_CAV.__init__(self,name,typ,para)
 
+#--
+
+class ERROR_FILE(COMM):
+    '''
+    '''
+    def __init__(self,name,typ,para):
+
+        COMM.__init__(self,name,typ,para)
+
+        # TW instances
+        self.file_name=str(para[0])
+
+    def get_tw(self):
+
+        if self.name!='': lin=self.name+': '+self.typ+' '
+        if self.name=='': lin=               self.typ+' '
+        lin+=str(self.file_name)
+
+        return lin
+
+class ERROR_STAT_FILE(ERROR_FILE):
+    '''
+    '''
+    def __init__(self,name,typ,para):
+
+        ERROR_FILE.__init__(self,name,typ,para)
+
+class ERROR_DYN_FILE(ERROR_FILE):
+    '''
+    '''
+    def __init__(self,name,typ,para):
+
+        ERROR_FILE.__init__(self,name,typ,para)
+        
 #----