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Safety Semantic Error: The output '...' is written more than once.

A global variable assigned to a physical device output (process data item) is written more than once. This is not allowed.

(Safety-related) global variables can be used in all (safety-related) POUs of the project. If they are written in several POUs, their handling may become incomprehensible and the signal flow untraceable across POU borders.
To maintain clarity where output variables are written in the project, they must only be written once. Reading them several times, however, is allowed.

Remedy:
  1. Double-click the error in the Error List to jump to the SNOLD code worksheet where the first write access to the variable is marked.
  2. Use the CROSS REFERENCES window to locate each code position in the project with write access to the affected variable.
    Create the cross references and filter the list for the suspected variable. See topic "CROSS REFERENCES Window" for details.
  3. Modify the code accordingly.