Siemens SIMATIC S7-400 Configuration And Use Manual page 102

Programming the S7-400
Diagnostics Buffer
A diagnostics buffer in the CPU is available for evaluating the history of diagnostic
events. The size of this diagnostics buffer depends on the type of CPU used
Example: A CPU with a diagnostics buffer for 200 diagnostic entries show the last
200 diagnostics entries. New incoming diagnostic messages overwrite the "oldest"
diagnostic entries.
Advantages
The testing and diagnostic options for the S7-400 offers you the following
advantages:
• Easy to understand because of a uniform system solution
• Less time needed for program testing and commissioning
• Fast error analysis and correction, increases plant availability
• Permits verification of prohibited and incorrect operations and manipulations
based on the entries in the diagnostics buffer (e.g. STOP SWITCH ACTIVATED
10/20/04 23:59; module removed ...)
7-6
Automation System S7-400 Configuration and Use
A5E00442711-02