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S7 Distributed Safety -- Product information -- Technical data
How do you incorporate the execution times of the F blocks for the Mobile Panel 277F IWLAN into the "S7fcotia.xls" table?
Why does my F system go into STOP at startup?
F Technology CPU 300/400 -- Product information -- Technical data
Where can you find images, graphics, symbols and screenshots for SIMATIC industrial automation systems?
What are the system limits in an F CPU for safe bidirectional data communication using S7 Communication?
How do you incorporate the execution times of the F blocks for the Mobile Panel 277F IWLAN into the "S7fcotia.xls" table?
Why does my F system go into STOP at startup?
Which values can you use with F CPUs and products of the ET 200 family for PFD, PFH and the proof test interval?
Which fail-safe signal modules of the distributed I/O can be combined with which fail-safe controllers?
Which hardware and software components are required to set up and operate an F system with SIMATIC S7-300F?
Why does my F system go into STOP at startup?
Part number:

Description:
When using S7 Distributed Safety V 5.4 SP1 to V 5.4 SP3, despite correct setting of the monitoring times it still might happen that when the F system starts up, the F CPU goes into STOP. In this case, you find the following entries in the diagnostics buffer:

  • "Cycle time exceeded" or
  • "Error in the safety program: cycle time exceeded".

Note:
With S7 Distributed Safety V 5.4 SP1 the behavior described can only occur when you are using an F CPU that supports "Startup protection in case of inconsistent safety program" (see Product Information for F CPU concerned).

The F CPU's operating mode STOP depends on the following:

  • Number of F peripherals addressed in the safety program.
  • Available time buffer in the value configured for the maximum cycle time of the F runtime group (F monitoring time).
  • Available time buffer in the value configured for the cycle monitoring time (in the "Cycle/Clock marker" tab in the Object Properties of the F CPU).

Remedy:
Execute the steps as in the table below.
 
No. Procedure Note
1 First check whether you have set the monitoring time correctly. Also refer here to the Excel file on response time calculation, s7cotia.xls, Entry ID 25412441.
2 Change to S7 Distributed Safety V 5.4 SP4. Instructions for this are available in the programming and operating manual "S7 Distributed Safety, Configuring and Programming", Edition 10/2007.
3 Generate the safety program with S7 Distributed Safety V 5.4 SP4.  

Keywords:
Safety Integrated, Fail-safe

 Entry ID:27832833   Date:2008-01-29 
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