<log4net>
    <appender name="FileAppender" type="log4net.Appender.FileAppender">
      <param name="File" value="<LogFileName>"/>
      <param name="AppendToFile" value="true"/>
      <maximumFileSize value="10MB"/>
      <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%d %level - %message%newline"/>
      </layout>
      <filter type="log4net.Filter.LevelRangeFilter">
        <param name="LevelMin" value="ERROR"/>
        <param name="LevelMax" value="ERROR"/>
      </filter>
    </appender>
    <logger name="ERP_CONNECTOR_LOGGER">
      <appender-ref ref="FileAppender"/>
    </logger>
</log4net>

Where <LogFileName> is the path and name of your log file.

If you want to include debug messages in the log file, set the LevelMin value to DEBUG.

For more information about these settings, refer to the log4net documentation on the Apache Foundation website.