use more robust function to convert from data type to variant type

Author: oroulet

opcua/common/node.py

@@ -75,7 +75,7 @@ def get_data_type_as_variant_type(self):
         may not be convertible to VariantType
         """
         result = self.get_attribute(ua.AttributeIds.DataType)
-        return ua.datatype_to_varianttype(result.Value.Value)
+        return opcua.common.ua_utils.data_type_to_variant_type(Node(self.server, result.Value.Value))
 
     def get_access_level(self):
         """