Basic IEC 61131-3 Functions (safety-related and standard)
Functions are POUs with multiple input parameters and one output parameter. As they do not have any internal memory, a function called with the same input values always returns the same result. The abbreviation for functions is FU.
IEC 61131-3 describes basic functions. A subset of these functions are implemented in EcoStruxure Machine Expert - Safety.
NOTE:
Term definition: Standard = non-safety-related
The term "standard" always refers to non-safety-related items. Examples: a standard process data item is only read/written by a non-safety-related I/O device (i.e., a standard device). Standard variables/functions/FBs are non-safety-related data. The term "standard controller" designates the non-safety-related controller.
NOTE:
Standard functions are only allowed for programming standard program parts.
When programming a safety-related application a strict separation between safety-related and standard logic (networks) is required. Due to this, all IEC 61131-3-defined functions are also available as safety-related functions.
Representation
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In the Edit Wizard the standard functions are represented by the symbol |
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Safety-related functions are represented by the symbol |
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, in a code worksheet they appear in gray accordingly:
in the Edit Wizard and appear in red when inserted in a code worksheet: