diff --git a/MultiTerm.Core/Model/MultiFormatString.cs b/MultiTerm.Core/Model/MultiFormatString.cs
index a7917dc..0337b77 100644
--- a/MultiTerm.Core/Model/MultiFormatString.cs
+++ b/MultiTerm.Core/Model/MultiFormatString.cs
@@ -1,4 +1,5 @@
 using MultiTerm.Core.Types;
+using System.Text;
 
 namespace MultiTerm.Core.Model;
 
@@ -8,8 +9,11 @@ public class MultiFormatString
 
     public void Add(FormatType format, string value)
     {
-        // TODO check if value is valid
-        this.FormatValuePairs.Add(Tuple.Create(format, value));
+        // check if value is valid, if yes add to FormatValuePairs
+        if (ValidateValue(format, value))
+        {
+            this.FormatValuePairs.Add(Tuple.Create(format, value));
+        }
     }
 
     public void Remove(int amount)
@@ -28,8 +32,140 @@ public class MultiFormatString
         this.FormatValuePairs.RemoveRange( (listCount - amount) , amount);
     }
 
+    // TODO Setup Unit Tests 
     public override string ToString()
     {
-        throw new NotImplementedException();
+        StringBuilder stringBuilder = new();
+        string hexConversionCharacters = String.Empty, binaryConversionCharacters = String.Empty;
+
+        // parameter == null will force ending
+        void finalizeHexConversion(Tuple<FormatType, string>? formatValuePair)
+        {
+            // hex conversion ongoing?
+            if (String.IsNullOrEmpty(hexConversionCharacters) == false)
+            {
+                // ending conversion or reached limit of characters?
+                if (formatValuePair == null ||
+                    formatValuePair.Item1 != FormatType.Hexadecimal ||
+                    hexConversionCharacters.Count() == 4)
+                {
+                    // finalize conversion
+                    stringBuilder.Append(FromHexString(hexConversionCharacters));
+                    // reset ongoing conversion
+                    hexConversionCharacters = String.Empty;
+                }
+            }
+        }
+
+        // parameter == null will force ending
+        void finalizeBinaryConversion(Tuple<FormatType, string>? formatValuePair)
+        {
+            // binary conversion ongoing?
+            if (String.IsNullOrEmpty(binaryConversionCharacters) == false)
+            {
+                // ending conversion or reached limit of characters?
+                if (formatValuePair == null ||
+                    formatValuePair.Item1 != FormatType.Binary ||
+                    binaryConversionCharacters.Count() == 16)
+                {
+                    // finalize conversion
+                    stringBuilder.Append(FromBinaryString(binaryConversionCharacters));
+                    // reset ongoing conversion
+                    binaryConversionCharacters = String.Empty;
+                }
+            }
+        }
+
+        foreach (var formatValuePair in this.FormatValuePairs)
+        {
+            finalizeHexConversion(formatValuePair);
+            finalizeBinaryConversion(formatValuePair);
+
+            switch (formatValuePair.Item1)  // switch by format
+            {
+                case FormatType.Character:
+                    stringBuilder.Append(formatValuePair.Item2);
+                    break;
+
+                case FormatType.Hexadecimal:
+                    hexConversionCharacters += formatValuePair.Item2;
+                    break;
+
+                case FormatType.Binary:
+                    binaryConversionCharacters += formatValuePair.Item2;
+                    break;
+
+                default:
+                    throw new NotImplementedException($"'{nameof(ToString)}()' does not implement conversion for format {formatValuePair.Item1}");
+            }
+        }
+
+        finalizeHexConversion(null);
+        finalizeBinaryConversion(null);
+
+        return stringBuilder.ToString();
     }
+
+
+    public static bool ValidateValue(FormatType format, string value)
+    {
+        // invalid if more than one character
+        if(value.Count() > 1) 
+        { return false; }
+
+        // extract character
+        var character = value.First();
+
+        switch (format)
+        {
+            case FormatType.Character:
+                return true;
+
+            case FormatType.Hexadecimal:
+                if (character >= '0' && character <= '9' ||
+                    character >= 'A' && character <= 'F' ||
+                    character >= 'a' && character <= 'f')
+                { return true; }
+                else
+                { return false; };
+
+            case FormatType.Binary:
+                if (character == '0' || character == '1')
+                { return true; }
+                else
+                { return false; };
+
+            default:
+                throw new NotImplementedException($"'{nameof(ValidateValue)}()' does not implement validation for format {format}");
+        }
+    }
+
+    // from: https://stackoverflow.com/questions/724862/converting-from-hex-to-string
+    // test with: returns: "Hello world" for "48656C6C6F20776F726C64"
+    // see https://www.fileformat.info/info/charset/UTF-16/list.htm
+    public static string FromHexString(string hexString)
+    {
+        // Added PadLeft so strings with one character do not get ignored
+        string internalHexString = hexString.PadLeft(4, '0');
+        var bytes = new byte[internalHexString.Length / 2];
+        for (var i = 0; i < bytes.Length; i++)
+        {
+            bytes[i] = Convert.ToByte(internalHexString.Substring(i * 2, 2), 16);
+        }
+
+        return Encoding.BigEndianUnicode.GetString(bytes);
+    }
+
+    public static string FromBinaryString(string binaryString)
+    {
+        string internalBinaryString = binaryString.PadLeft(16, '0');
+        var bytes = new byte[internalBinaryString.Length / 8];
+        for (var i = 0; i < bytes.Length; i++)
+        {
+            bytes[i] = Convert.ToByte(internalBinaryString.Substring(i * 8, 8), 2);
+        }
+
+        return Encoding.BigEndianUnicode.GetString(bytes);
+    }
+
 }
diff --git a/MultiTerm.Core/ViewModel/SendReceiveViewModel.cs b/MultiTerm.Core/ViewModel/SendReceiveViewModel.cs
index 864373a..b72c5bd 100644
--- a/MultiTerm.Core/ViewModel/SendReceiveViewModel.cs
+++ b/MultiTerm.Core/ViewModel/SendReceiveViewModel.cs
@@ -1,4 +1,5 @@
 using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
 using MultiTerm.Core.Model;
 using MultiTerm.Core.Types;
 
@@ -20,4 +21,19 @@ public partial class SendReceiveViewModel : TerminalViewModel
     /// </summary>
     [ObservableProperty]
     private MultiFormatString sendData = new();
+
+    /// <summary>
+    /// Temporary sent data property, for testing purposes.
+    /// </summary>
+    [ObservableProperty]
+    private string sentData = string.Empty;
+
+    /// <summary>
+    /// Send command.
+    /// </summary>
+    [RelayCommand]
+    private void Send()
+    {
+        this.SentData = this.SendData.ToString();
+    }
 }
diff --git a/MultiTerm.Wpf/View/SendReceiveView.xaml b/MultiTerm.Wpf/View/SendReceiveView.xaml
index 7d3a303..8a9c6bc 100644
--- a/MultiTerm.Wpf/View/SendReceiveView.xaml
+++ b/MultiTerm.Wpf/View/SendReceiveView.xaml
@@ -38,13 +38,13 @@
                 <!-- Send text box -->
                 <DockPanel DockPanel.Dock="Top" LastChildFill="True">
                     <!--<TextBox Width="700"></TextBox>-->
-                    <Button DockPanel.Dock="Right" Content="Send"/>
-                    <custom_controls:MultiFormatTextBox DockPanel.Dock="Left" CurrentMultiFormatString="{Binding SendData}"></custom_controls:MultiFormatTextBox>
+                    <Button DockPanel.Dock="Right" Content="Send" Command="{Binding SendCommand}"/>
+                    <custom_controls:MultiFormatTextBox DockPanel.Dock="Left" CurrentMultiFormatString="{Binding Path=SendData, Mode=TwoWay}"></custom_controls:MultiFormatTextBox>
                 </DockPanel>
                 <Separator/>
-                <RichTextBox DockPanel.Dock="Bottom">
+                <TextBox DockPanel.Dock="Bottom" Text="{Binding SentData}">
                     
-                </RichTextBox>
+                </TextBox>
             </DockPanel>
         </GroupBox>
     </Grid>