Update IP4address if have null reading.

Create Nullchannel and null exception

csharp/Lib/Protocols/Modbus/Channels/NullChannel.cs

@@ -0,0 +1,14 @@
+namespace InnovEnergy.Lib.Protocols.Modbus.Channels;
+
+public class NullChannel : Channel
+{
+    public override IReadOnlyList<Byte> Read(Int32 nBytes) => throw new NullChannelException();
+
+    public override void Write(IReadOnlyList<Byte> bytes)
+    {
+    }
+}
+
+public class NullChannelException : Exception
+{
+}

csharp/Lib/Protocols/Modbus/Channels/TcpChannel.cs

@@ -11,8 +11,8 @@ public class TcpChannel : ConnectionChannel<TcpClient>
     public TcpChannel(Ip4Address ip4Address,
                          Boolean closeAfterSuccessfulRead  = false,
                          Boolean closeAfterSuccessfulWrite = false) : 
-        this(ip4Address.Host, 
+        this(ip4Address.Host ?? "null",
-             ip4Address.Port, 
+             ip4Address.Port.HasValue ? (Int32)ip4Address.Port.Value : 0, 
              closeAfterSuccessfulRead, 
              closeAfterSuccessfulWrite)
     {

csharp/Lib/Utils/Net/Ip4Address.cs

@@ -1,9 +1,11 @@
+using System.Net;
+
 namespace InnovEnergy.Lib.Utils.Net;
 
 public class Ip4Address
 {
-    public required String Host { get; init; }
+    public required String? Host { get; init; }
-    public required UInt16 Port { get; init; }
+    public required UInt16? Port { get; init; }
 
     public override String ToString() => $"{Host}:{Port}";
 
@@ -18,6 +20,7 @@ public class Ip4Address
         if (ReferenceEquals(null, obj)) return false;
         if (ReferenceEquals(this, obj)) return true;
         if (obj.GetType() != GetType()) return false;
+
         return Equals((Ip4Address)obj);
     }
 
@@ -26,3 +29,11 @@ public class Ip4Address
 
     public override Int32 GetHashCode() => ToString().GetHashCode();
 }
+
+
+
+
+
+    
+
+