Tab: Log
Log
The Log tab displays the log of the safety controller. It is used as a log and to diagnose runtime errors of the application and system errors. It can help to find the cause of an error in the controller or in the application.
Two logs are available in CODESYS Safety Extension:
Device log
Application log
The device log belongs to the device and is intended for entries that concern the device, e.g. system errors, generation of new boot applications.
The application log belongs to the IEC application and is intended for entries that concern the application, e.g. runtime errors, errors during the loading of the boot application and online communication errors.
The application log is the default log of the safety controller. The device log is available only after the default log (application log) has been loaded.
When the 
button is pressed, all available logs (device and application logs) are loaded from the controller and they can be selected in the Logger list box. After selecting a log, the button has to be pressed in order to update the entries in the selected log.
When changes are entered due to online accesses, the name of the developer is also logged. Since there is no user management on the controller, the name of the developer from the user management in the development system is used. If the developer is not logged in to the development system as a specific user, but as one of the predefined users, the user name from the Windows user management is used instead.
For a basic description of the Log tab, see the CODESYS help.
Generation of the log entries
Log entries are generated in particular if the boot application cannot be loaded in offline mode for any reason and a system error occurs.
A system error is also generated if the log cannot be written to when the runtime system attempts to load the boot application on booting up.
Tip
If the log does not indicate the cause of a system error, then the reason for this system error could be that the log could not be written to by the safety-oriented runtime system.
Important
In the case of hardware errors it is possible that not all entries could be written in the log.
A log entry is generated
Whenever the runtime system is in offline mode (i.e. when booting up without an online connection) and reacts to an error in the application in accordance with a safety requirement by aborting the loading procedure.
Whenever the runtime system is in offline mode and reacts to an application error by terminating the execution of the application.
When swapping the boot application with the last boot load or the last generation of a boot application. This is recognized by the runtime system.
In the case of a falsified or mismatching execution version of the runtime system.
Logging of changes in the boot application
Logging of firmware updates
Logging of the generation of new boot applications
Log entry in the case of a runtime error
If the application is terminated because of a runtime error, the generated log entry contains the following information:
Name of the erroneous POU
Number of the erroneous network of the POU
For an FB POU: Function block instance where the error occurred