diff --git a/Sharp7.Rx/S7ErrorCodes.cs b/Sharp7.Rx/S7ErrorCodes.cs
index f076bf8..5e54922 100644
--- a/Sharp7.Rx/S7ErrorCodes.cs
+++ b/Sharp7.Rx/S7ErrorCodes.cs
@@ -1,4 +1,6 @@
-namespace Sharp7.Rx;
+#nullable enable
+
+namespace Sharp7.Rx;
 
 public static class S7ErrorCodes
 {
@@ -12,6 +14,18 @@ public static class S7ErrorCodes
         0x900000, // CPU: Address out of range
     };
 
+    private static readonly IReadOnlyDictionary<int, string> additionalErrorTexts = new Dictionary<int, string>
+    {
+        {0xC00000, "This happens when the DB does not exist."},
+        {0x900000, "This happens when the DB is not long enough."},
+        {
+            0x40000, """
+                     This error occurs when the DB is "optimized" or "PUT/GET communication" is not enabled.
+                     See https://snap7.sourceforge.net/snap7_client.html#target_compatibility.
+                     """
+        }
+    };
+
     /// <summary>
     ///     Some error codes indicate connection lost, in which case, the driver tries to reestablish connection.
     ///     Other error codes indicate a user error, like reading from an unavailable DB or exceeding
@@ -21,4 +35,7 @@ public static class S7ErrorCodes
     {
         return !notDisconnectedErrorCodes.Contains(errorCode);
     }
+
+    public static string? GetAdditionalErrorText(int errorCode) =>
+        additionalErrorTexts.TryGetValue(errorCode, out var text) ? text : null;
 }
diff --git a/Sharp7.Rx/Sharp7Connector.cs b/Sharp7.Rx/Sharp7Connector.cs
index 695e20d..9e4ceca 100644
--- a/Sharp7.Rx/Sharp7Connector.cs
+++ b/Sharp7.Rx/Sharp7Connector.cs
@@ -12,18 +12,6 @@ namespace Sharp7.Rx;
 
 internal class Sharp7Connector : IS7Connector
 {
-    private static readonly IReadOnlyDictionary<int, string> additionalErrorTexts = new Dictionary<int, string>
-    {
-        {0xC00000, "This happens when the DB does not exist."},
-        {0x900000, "This happens when the DB is not long enough."},
-        {
-            0x40000, """
-                     This error occurs when the DB is "optimized" or "PUT/GET communication" is not enabled.
-                     See https://snap7.sourceforge.net/snap7_client.html#target_compatibility.
-                     """
-        }
-    };
-
     private readonly BehaviorSubject<ConnectionState> connectionStateSubject = new(Enums.ConnectionState.Initial);
     private readonly int cpuSlotNr;
 
@@ -239,7 +227,8 @@ internal class Sharp7Connector : IS7Connector
         var errorText = EvaluateErrorCode(result);
         var completeMessage = $"{message}: {errorText}";
 
-        if (additionalErrorTexts.TryGetValue(result, out var additionalErrorText))
+        var additionalErrorText = S7ErrorCodes.GetAdditionalErrorText(result);
+        if (additionalErrorText != null)
             completeMessage += Environment.NewLine + additionalErrorText;
 
         throw new S7CommunicationException(completeMessage, result, errorText);
diff --git a/Sharp7.Rx/Sharp7Plc.cs b/Sharp7.Rx/Sharp7Plc.cs
index b799924..8eff549 100644
--- a/Sharp7.Rx/Sharp7Plc.cs
+++ b/Sharp7.Rx/Sharp7Plc.cs
@@ -17,7 +17,7 @@ public class Sharp7Plc : IPlc
     private readonly ConcurrentSubjectDictionary<string, byte[]> multiVariableSubscriptions = new(StringComparer.InvariantCultureIgnoreCase);
     private readonly List<long> performanceCoutner = new(1000);
     private readonly PlcConnectionSettings plcConnectionSettings;
-    private readonly IVariableNameParser varaibleNameParser = new CacheVariableNameParser(new VariableNameParser());
+    private readonly CacheVariableNameParser varaibleNameParser = new CacheVariableNameParser(new VariableNameParser());
     private bool disposed;
     private Sharp7Connector s7Connector;