Language-Specific Programming Guidelines - ABB AC500-S Safety User Manual

Configuration and programming
CoDeSys Safety programming guidelines > Language-specific programming guidelines
4.4.2.5 Settings
Table 10: The following system settings are required:
Setting
Replace constants
Actions hide programs
4.4.2.6 Classification
In 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 to
a limited extent and compliance with additional fault prevention measures is strongly recommended. These
measures are listed with the respective construct.

4.4.3 Language-specific programming guidelines

4.4.3.1 Safety-related restrictions for developers
There are some restrictions to developing safety applications with CoDeSys V2.3.x which have to be
secured by organisational means. These are as follows:
n For Safety Applications, CoDeSys visualisations are allowed for Displaying purposes only. Changing
values via controls (
would cause the run-time system to switch into non-safe mode without necessarily telling the user.
4.4.3.2 Language
Of the five IEC 61131-3 languages implemented in CoDeSys V2.3, "Structured Text" (ST), "Function Block
Diagram" (FBD) and "Ladder Logic" (LD) are approved for creating safety-oriented applications.
4.4.3.3 Task system
Due 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 be
called 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.
The controller-specific options for monitoring total execution time must be activated and set significantly
n
below the fault tolerance time.
212
Ä Chapter 4.4.2.3 "Control-specific application notes" on page 211 "Write values")
Value
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AC500-S 30.03.2017