diff --git a/S7.Net.UnitTest/Helpers/TestStruct.cs b/S7.Net.UnitTest/Helpers/TestStruct.cs
index 7171d83..f07688a 100644
--- a/S7.Net.UnitTest/Helpers/TestStruct.cs
+++ b/S7.Net.UnitTest/Helpers/TestStruct.cs
@@ -58,7 +58,8 @@ namespace S7.Net.UnitTest.Helpers
         /// <summary>
         /// DB1.DBX20.0
         /// </summary>
-        [S7String(S7StringType.S7WString, 10)] public string WStringVariable;
+        [S7String(S7StringType.S7WString, 10)] 
+        public string WStringVariable;
 
         /// <summary>
         /// DB1.DBX44.0
diff --git a/S7.Net/Types/S7StringAttribute.cs b/S7.Net/Types/S7StringAttribute.cs
index 50ad5fc..3c7a415 100644
--- a/S7.Net/Types/S7StringAttribute.cs
+++ b/S7.Net/Types/S7StringAttribute.cs
@@ -57,11 +57,11 @@ namespace S7.Net.Types
         /// <summary>
         /// ASCII string.
         /// </summary>
-        S7String,
+        S7String = VarType.S7String,
 
         /// <summary>
         /// Unicode string.
         /// </summary>
-        S7WString
+        S7WString = VarType.S7WString
     }
 }
diff --git a/S7.Net/Types/Struct.cs b/S7.Net/Types/Struct.cs
index 5f18980..357820c 100644
--- a/S7.Net/Types/Struct.cs
+++ b/S7.Net/Types/Struct.cs
@@ -65,7 +65,7 @@ namespace S7.Net.Types
                     case "String":
                         S7StringAttribute? attribute = info.GetCustomAttributes<S7StringAttribute>().SingleOrDefault();
                         if (attribute == default(S7StringAttribute))
-                            throw new ArgumentException("Please add S7StringAttribute to the field you are trying to read or write");
+                            throw new ArgumentException("Please add S7StringAttribute to the string field");
 
                         numBytes = Math.Ceiling(numBytes);
                         if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
@@ -192,7 +192,7 @@ namespace S7.Net.Types
                     case "String":
                         S7StringAttribute? attribute = info.GetCustomAttributes<S7StringAttribute>().SingleOrDefault();
                         if (attribute == default(S7StringAttribute))
-                            throw new ArgumentException("Please add S7StringAttribute to the field you are trying to read or write");
+                            throw new ArgumentException("Please add S7StringAttribute to the string field");
 
                         numBytes = Math.Ceiling(numBytes);
                         if ((numBytes / 2 - Math.Floor(numBytes / 2.0)) > 0)
@@ -294,7 +294,7 @@ namespace S7.Net.Types
                     case "String":
                         S7StringAttribute? attribute = info.GetCustomAttributes<S7StringAttribute>().SingleOrDefault();
                         if (attribute == default(S7StringAttribute))
-                            throw new ArgumentException("Please add S7StringAttribute to the field you are trying to read or write");
+                            throw new ArgumentException("Please add S7StringAttribute to the string field");
 
                         bytes2 = attribute.Type switch
                         {