Add clear buffer for serialPort

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

@@ -36,7 +36,23 @@ public class SerialPortChannel : ConnectionChannel<SerialPort>
             return serialPort;
         };
     }
-
+    
+    // 👇 NEW: this is where we actually flush the serial buffers
+    protected override void ClearBuffers(SerialPort serialPort)
+    {
+        try
+        {
+            serialPort.DiscardInBuffer();
+            serialPort.DiscardOutBuffer();
+            Console.WriteLine(" Buffer in and out discarded.");
+        }
+        catch
+        {
+            Console.WriteLine(" couldn't clear the Buffer .");
+            // ignore if port is closed / disposed
+        }
+    }
+    
     protected override SerialPort Open() => _Open();
 
     protected override void Close(SerialPort serialPort) => serialPort.Dispose();