Functional Safety Known Issues

Functional Safety Editor loses transition condition when editing in the right rail

If a user places two states on the block diagram and connects them with a transition then clicks on the transition label and adds text, the transition label text can disappear if the user clicks anywhere else on the block diagram.

Workaround: Right-click the transition wire and choose "create transition condition" to enter text instead of clicking on the wire itself. 

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Compound states do not correctly resize for long transition conditions.

Compound states do not expand to fit large transition conditions, which can result in some text being hidden. When the compound state is manually expanded to fit the wire transition condition, the right side expands oddly. Once expanded correctly, the compound state cannot be made smaller than wire transition condition manually.

Workaround: Manually expand the compound state. Alternatively, use multiple lines on the transition.  

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Transition logic that is semantically equivalent to FALSE before compilation does not function correctly.

If the transition logic between two states that can be simplified by inspection to FALSE (for example, A && !A), then the transition will always execute. Such logic should fail the required safety logic validation requirements in the C Series Functional Safety Manual prior to reaching a deployed state. However, setting a transition logic to FALSE can be useful while debugging a User Program. Do not rely on this technique when developing and testing User Programs with the Functional Safety Editor September 2017.

Workaround: If debugging a User Program, use a Boolean variable to isolate code instead of FALSE.  

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Transition conditions can change locations when loaded from file.

With a state machine containing transitions:  Save it, close it, then re-open it.  One or more transition wires may have moved and no longer looks "clean". This can also appear as issue #656340: when moving multiple items simultaneously (mass select), occasionally one or more of the transition conditions does not move concurrently.

Workaround: N/A  

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If you save the User Program while editing a text box, the changes to the text box are not committed.

If you try to save the document while editing a text box in the right rail or on the diagram, the changes to the text box are not reflected in the saved file.

Workaround: Deselect the text box by clicking out of it prior to saving.  

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Cannot open files of the same name.

If you have opened a given .FSP file, that name is now 'reserved' by the Functional Safety Editor for that particular copy of the file.  If you try to open a file of the same name from a different directory you will get an error. This is also embodied in issue #644840: if you try to 'Save As' a .FSP file with the same name but in a different directory, the subsequent compilation will fail.

Workaround: To open the other file, close the Functional Safety Editor to reset its session memory. Then, open the second file with a fresh instance of the Functional Safety Editor.  

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Creating a compound state over an existing state pushes the transition conditions to the outside of the compound state, breaking the transitions.

Start with two or more states and a transition between them with some logic. Drop (or "ring") one of the destination states with a new compound state. You will see the transition condition get pushed to outside the compound state. This is an invalid location that results in a broken wire.

Workaround: Delete the internal wire segment and rewire. This will move the transition condition inside. Or, copy the transition condition to the existing segment inside the compound state and delete the external transition condition. 

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For digital inputs with a discrepancy time specified, the actual discrepancy time allowed by the module could differ.

The actual discrepancy time allowed between dual channels is slightly shorter from the time configured in the Functional Safety Editor due to signal routing and counter timebases.  This results in the slightly more conservative behavior with the assertion of the discrepancy fault sooner than specified discrepancy time. The time will be shorter by the Minimum Discrepancy Timer. This time can be found in the C Series Functional Safety Manual under "Minimum Discrepancy Timer."

For example, for a Dual Input configured with 500 us discrepancy in the Functional Safety, the discrepancy at the board could be staggered as much as 500 us - MinimumDiscrepancyTimer (100 us) = 400 us.

Workaround: N/A  

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