diff --git a/tangostationcontrol/tangostationcontrol/toolkit/archiver_util.py b/tangostationcontrol/tangostationcontrol/toolkit/archiver_util.py
index 2929dca36608552955953f2947c36c137948b7c9..0d5e8f4d992170016bae7405c204b785c8cb8573 100644
--- a/tangostationcontrol/tangostationcontrol/toolkit/archiver_util.py
+++ b/tangostationcontrol/tangostationcontrol/toolkit/archiver_util.py
@@ -7,6 +7,20 @@
 from tango import DeviceProxy, CmdArgType
 import re
 
+"""
+A dictionary whose keys are the Tango datatypes mapping, and the values are the relative byte size
+See reference https://tango-controls.readthedocs.io/en/latest/development/advanced/reference.html#tango-data-type
+and https://www.tutorialspoint.com/cplusplus/cpp_data_types.htm
+TODO: manage String attributes
+"""
+DATATYPES_SIZE_DICT = {CmdArgType.DevBoolean:1, CmdArgType.DevShort:2, CmdArgType.DevLong:8, CmdArgType.DevFloat:4, CmdArgType.DevDouble:8, 
+    CmdArgType.DevUShort:2, CmdArgType.DevULong:8, CmdArgType.DevString:20, CmdArgType.DevVarCharArray:None, CmdArgType.DevVarShortArray:None, 
+    CmdArgType.DevVarLongArray: None,CmdArgType.DevVarFloatArray:None, CmdArgType.DevVarDoubleArray:None, CmdArgType.DevVarUShortArray:None,
+    CmdArgType.DevVarULongArray: None, CmdArgType.DevVarStringArray: None, CmdArgType.DevVarLongStringArray: None, CmdArgType.DevVarDoubleStringArray:None,
+    CmdArgType.DevState:3, CmdArgType.ConstDevString:None, CmdArgType.DevVarBooleanArray:None, CmdArgType.DevUChar:1, CmdArgType.DevLong64:8,
+    CmdArgType.DevULong64:8,CmdArgType.DevVarLong64Array:None,CmdArgType.DevVarULong64Array:None, CmdArgType.DevInt:4,CmdArgType.DevEncoded:None, 
+    CmdArgType.DevEnum:None, CmdArgType.DevPipeBlob:None}
+
 def get_db_config(device_name:str) -> dict:
     """
     Retrieve the DB credentials from the Tango properties of Configuration Manager or EventSubscribers
@@ -105,28 +119,11 @@ def retrieve_attributes_from_wildcards(device_name: str, matching_list: list):
                 matched_list.append(a)
     return matched_list
 
-def DATATYPES_SIZE_DICT() -> dict:
-    """
-    Return a dictionary whose keys are the Tango datatypes mapping, and the values are the relative byte size
-    See reference https://tango-controls.readthedocs.io/en/latest/development/advanced/reference.html#tango-data-type
-    and https://www.tutorialspoint.com/cplusplus/cpp_data_types.htm
-    TODO: manage String attributes
-    """
-    datatypes_dict = {CmdArgType.DevBoolean:1, CmdArgType.DevShort:2, CmdArgType.DevLong:8, CmdArgType.DevFloat:4, CmdArgType.DevDouble:8, 
-        CmdArgType.DevUShort:2, CmdArgType.DevULong:8, CmdArgType.DevString:20, CmdArgType.DevVarCharArray:None, CmdArgType.DevVarShortArray:None, 
-        CmdArgType.DevVarLongArray: None,CmdArgType.DevVarFloatArray:None, CmdArgType.DevVarDoubleArray:None, CmdArgType.DevVarUShortArray:None,
-        CmdArgType.DevVarULongArray: None, CmdArgType.DevVarStringArray: None, CmdArgType.DevVarLongStringArray: None, CmdArgType.DevVarDoubleStringArray:None,
-        CmdArgType.DevState:3, CmdArgType.ConstDevString:None, CmdArgType.DevVarBooleanArray:None, CmdArgType.DevUChar:1, CmdArgType.DevLong64:8,
-        CmdArgType.DevULong64:8,CmdArgType.DevVarLong64Array:None,CmdArgType.DevVarULong64Array:None, CmdArgType.DevInt:4,CmdArgType.DevEncoded:None, 
-        CmdArgType.DevEnum:None, CmdArgType.DevPipeBlob:None}
-    return datatypes_dict
-
 def get_size_from_datatype(datatype:int) -> int:
     """
     Return the number of bytes for a given Tango datatype
     """
-    datatypes_dict = DATATYPES_SIZE_DICT()
     try :
-        return datatypes_dict[datatype]
+        return DATATYPES_SIZE_DICT[datatype]
     except IndexError:
         return 1