diff --git a/NucuCar.Domain/Readme.md b/NucuCar.Domain/Readme.md
index 90b6c4d..41289ab 100644
--- a/NucuCar.Domain/Readme.md
+++ b/NucuCar.Domain/Readme.md
@@ -35,3 +35,20 @@ export Telemetry:ConnectionString=CONNECTION_STRING
 
 A telemetry reader can be found in NucuCar.TestClient. You'll need a connection string that can be found in
 Azure's IoT Hub Build-In Endpoints setting.
+
+---
+
+### Disk Telemetry
+
+#### Publisher
+
+Publishes telemetry on the disk.
+
+Example connection string:
+`Filename=telemetry;FileExtension=csv;Separator=,;BufferSize=4096`
+
+See the source code for comments on the ConnectionString.
+
+### Reader
+
+You will need to parse the file by yourself.
\ No newline at end of file
diff --git a/NucuCar.Domain/Telemetry/TelemetryPublisherDisk.cs b/NucuCar.Domain/Telemetry/TelemetryPublisherDisk.cs
index 049a17a..fae15f0 100644
--- a/NucuCar.Domain/Telemetry/TelemetryPublisherDisk.cs
+++ b/NucuCar.Domain/Telemetry/TelemetryPublisherDisk.cs
@@ -16,13 +16,15 @@ namespace NucuCar.Domain.Telemetry
     public class TelemetryPublisherDisk : TelemetryPublisher
     {
         private readonly FileStream _fileStream;
+        private readonly string _separator;
 
         /// <summary>
         /// Constructs an instance of <see cref="TelemetryPublisherDisk"/>.
         /// <remarks>
         ///    The connection string must contain the following options:
         ///     Filename (required) - The path of the filename in which to log telemetry data.
-        ///     FileExtension (optional) - The extension of the filename. Default txt
+        ///     FileExtension (optional) - The extension of the filename. Default csv
+        ///     Separator (optional) - The separator of the messages. Default ,
         ///     BufferSize (optional) - The buffer size for the async writer. Default: 4096
         /// </remarks>
         /// </summary>
@@ -31,9 +33,10 @@ namespace NucuCar.Domain.Telemetry
         {
             var connectionStringParams = ConnectionStringParser.Parse(opts.ConnectionString);
             var fileName = connectionStringParams.GetValueOrDefault("FileName");
-            var fileExtension = connectionStringParams.GetValueOrDefault("FileExtension", "txt");
+            var fileExtension = connectionStringParams.GetValueOrDefault("FileExtension", "csv");
             var bufferSize = connectionStringParams.GetValueOrDefault("BufferSize", "4096");
-
+            _separator = connectionStringParams.GetValueOrDefault("Separator", ",");
+            
             _fileStream = new FileStream(NormalizeFilename(fileName, fileExtension), FileMode.Append, FileAccess.Write,
                 FileShare.Read, int.Parse(bufferSize), true);
             Logger?.LogDebug("Initialized the TelemetryPublisherDisk!");
@@ -44,7 +47,7 @@ namespace NucuCar.Domain.Telemetry
             var data = GetTelemetry();
             var messageString = JsonConvert.SerializeObject(data);
             Logger?.LogDebug($"Telemetry message: {messageString}");
-            var encodedText = Encoding.Unicode.GetBytes(messageString);
+            var encodedText = Encoding.Unicode.GetBytes($"{messageString}{_separator}");
 
             try
             {