Technical data

Diagnostics
23.8 Flow of Diagnostic Information
Programming with STEP 7
Manual, 05/2010, A5E02789666-01 495
23.8 Flow of Diagnostic Information
The following figure shows the flow of diagnostic information in SIMATIC S7.
Displaying Diagnostic Information
You can read out the diagnostic entries using SFC51 RDSYSST in the user program or display the
diagnostic messages in plain language with STEP 7.
They provide information about the following:
• Where and when the error occurred
• The type of diagnostic event to which the entry belongs (user-defined diagnostic event,
synchronous/asynchronous error, operating mode change).
Generating Process Control Group Messages
The CPU enters events of the standard diagnostics and extended diagnostics in the diagnostic
buffer. It also generates a process control group message for the standard diagnostic events if the
following conditions are met:
• You have specified that process control messages will be generated in STEP 7.
• At least one display unit has logged on at the CPU for process control messages.
• A process control group message is only generated when there is not currently a process
control group message of the corresponding class (there are seven classes).
• One process control group message can be generated per class.