Precaution:

In this case, the log file is captured by the framework and configured by the DLL. We are using the TwinCAT HMI framework as an example.

It is very easy to log data by following the steps:

STEP 1:

Add a log4net.config file in the  extension DLL project (The file should be copied to for R&D C:\TwinCAT\Functions\TE2000-HMI-Engineering\Infrastructure\TcHmiServer\Latest\win-x86 ):

C:\TwinCAT\Functions\TF2000-HMI-Server\API\1.3.0.0\net48 folder contains logfile.log

C:\TwinCAT\Functions\TF2000-HMI-Server contains the log4net.config file

<log4net>
  <root>
    <level value="ALL" />
    <appender-ref ref="file" />
  </root>
  //Add the following if you have Nhibernate module and want to avoid debug log from Nhibernate
 <logger name="NHibernate">
   <level value="ERROR" />
 </logger>
 <logger name="NHibernate.SQL">
   <level value="ERROR" />
 </logger>
 //Add upto this
  <appender name="file" type="log4net.Appender.RollingFileAppender">
    <file value="logfile.log" />
    <appendToFile value="true" />
    <rollingStyle value="Size" />
    <maxSizeRollBackups value="5" />
    <maximumFileSize value="10MB" />
    <staticLogFileName value="true" />
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%date [%thread] %level %logger - %message%newline" />
    </layout>
  </appender>
</log4net>

If we want to create the log file to a particular directory we can change like the following though @ can’t be used in the config file. In this case, we have log file in the temp folder.

<file value="c:\\temp\\logfiletest.txt" /> 

See a complete example: https://www.hemelix.com/scada-hmi/twincat-hmi/data-grid-view/

STEP 2:

Add the log4net DLL as a reference to the project

STEP 3:

            C# extension project wizard does not generate the constructor, you need to build a constructor where you set the log4net configuration. We need to copy the log4net.config file to the following folder. 

 
C:\TwinCAT\Functions\TE2000-HMI-Engineering\\Bin\\x86\TcHmiEngineeringExtensions.Server\
And actual log file will be generated to C:\TwinCAT\Functions\TE2000-HMI-Engineering\Infrastructure\TcHmiServer\1.10.1336.404\Win32\logfile.log
Configure the constructor.
 
string s = AssemblyDirectory;
string path1 = System.Reflection.Assembly.GetAssembly(typeof(ServerExtensionCSharpEmpty1)).Location;
string directory = Path.GetDirectoryName(path1);
var ss = System.IO.Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
if (!log4net.LogManager.GetRepository().Configured) {
  s = "C:\\TwinCAT\\Functions\\TE2000-HMI-Engineering\\Infrastructure\\TcHmiServer\\Latest\\win-x86\\log4net.config";
  var configFile = new FileInfo(s);
  if (!configFile.Exists) {
    throw new FileLoadException(String.Format("The configuration file {0} does not exist", configFile));
  }
  log4net.Config.XmlConfigurator.Configure(configFile);
}
sqlConnector = new SQLConnecter();
sqlConnector.Do();
initDone = true;
log.Info("path1 =" + path1);
log.Info("s =" + s);
log.Info("ss =" + ss);
log.InfoFormat("Initializing WriteValueInit {0}", command.WriteValue);

STEP 4:

           We use the log method   to log in to the file:

                         switch (mapping)
                          {
                            case "RandomValue":
                                log.Info("Accessing random value");
                                ret = RandomValue(command);
                                break;

                            case "MaxRandom":
                                log.Info("Setting max random value");
                                ret = MaxRandom(command);
                                break;