4.4.2.5 SettingsTable 10: The following system settings are required:Setting ValueReplace constants Selected in Project/Options/BuildActions hide programs Selected in Project/Options/Build4.4.2.6 ClassificationIn principle most language constructs can be used in safety-oriented applications. However, for some con-structs that are associated with an increased fault potential during application creation this is only possible toa limited extent and compliance with additional fault prevention measures is strongly recommended. Thesemeasures are listed with the respective construct.4.4.3 Language-specific programming guidelines4.4.3.1 Safety-related restrictions for developersThere are some restrictions to developing safety applications with CoDeSys V2.3.x which have to besecured by organisational means. These are as follows:n For Safety Applications, CoDeSys visualisations are allowed for Displaying purposes only. Changingvalues via controls (Ä Chapter 4.4.2.3 “Control-specific application notes” on page 211 “Write values”)would cause the run-time system to switch into non-safe mode without necessarily telling the user.4.4.3.2 LanguageOf the five IEC 61131-3 languages implemented in CoDeSys V2.3, “Structured Text” (ST), “Function BlockDiagram” (FBD) and “Ladder Logic” (LD) are approved for creating safety-oriented applications.4.4.3.3 Task systemDue to poor testability it is only advisable to a limited extend to use multitasking for safety-oriented applica-tions. For application with CoDeSys this means:n The complete application consisting of safety-oriented parts and non-safety-oriented parts should becalled from program “PLC_PRG”. To achieve a well arranged structure of the program, no logic pro-cessing should be programmed in “PLC_PRG”. Assignments, calls to programs, function blocks or func-tions are allowed.n The controller-specific options for monitoring total execution time must be activated and set significantlybelow the fault tolerance time.Configuration and programmingCoDeSys Safety programming guidelines > Language-specific programming guidelines30.03.2017AC500-S212
