Why does my F system go into STOP at startup?
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".
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).
Execute the steps as in the table below.
|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.|
Safety Integrated, Fail-safe