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Safety Semantic Error: The variable '...' is not defined.

The variable mentioned in the error message is used in the code but it is not declared in the variables table of the respective POU. The error message appears in addition to the error message SEM1036 ("The variable '...' does not exist") of the standard (non-safety-related) semantic analysis.

Remedy:

  1. Double-click the error in the Error List (MESSAGES window) to jump to the suspected code worksheet (where the variable is marked).
  2. Right-click on the variable and select 'Create New Variable > Variable type' from the context menu, or left-click the variable and select the appropriate in-place button:

    local variable
    input variable in an FB POU
    output variable in an FB POU
    external variable

  3. Set the variable properties (data type, initial value, various flags, etc.) in the 'Variables' table.

Further Info
Refer to the topics "Variable Properties" and Variable Declaration Keywords" for details.