Hello Montalvo;

In the same screen that you sent us click on the Diagnostic Buffer tab. It normally contains information on problems encountered by the CPU that lead to active diagnostic LEDs.

SF means System Fault : programming error, access to non-available adresses in the program  (as when a remote I/O module connection is defective); BUSxF indicates an error on a network link, such as Profibus.

The normal operation of the CPU should be to go to STOP mode when such errors appear. But, if the program has been well-designed, special program blocks known as diagnostic OBs (OB86, OB122...) have been downloaded to the CPU program. These allow the CPU to continue operating even n the presence of certain specific types of fault, while the LEDs remain active to indicate that there is something you should correct.

As stated, open the diagnostic buffer, open the individual messages logged there, look into the problems detected and the corrections possible.

If you have trouble with the messages, save thaem (as a text file) and post them here so we can help you understand them better.

Hope this helps,

Daniel Chartier

Hello altin;

If you pay attention to the post that was written in answer to Montalvo'as original question, you will see that the easiest way to understand the problems that activate the LEDs SF and BF, is to open the Diagnostic buffer and read the logged CPU messages that you find there.

You can click on the Help button for details on each message, or, if you cannot understand the format of the messages, simply click on the Save As button to build a text file of all available messages that you can then attach to this thread. That way we can help you analyse the diagnostic buffer messages and find out the source of your problem.

hope this helps,

Daniel Chartier