Table 13: CoDeSys safety programming rules which have to be checked manually (ABB SCA tool is not able
to detect them in the safety application program)
Rule for manual check in CoDeSys Safety
Comments (Relevance for AC500-S)
Verify that the watchdog is activated. Verify that the watchdog
time is set sufficiently shorter than the process failure response
time.
Use a special library POU
SF_WDOG_TIME_SET (
details)
Verify that there is only one task.
AC500-S supports only one task, thus,
there is no need for this check.
Verify that, other than standard libraries, only libraries certified
for safety applications are used.
These rules are included in AC500-S
“Checklist for Creation of Safety Applica-
tion Program”
For each POU, verify that there are no unnecessary state varia-
bles.
Verify that the following holds for all function blocks: If more than
one variable is used to store state information, encapsulate
these variables into their own function block and only use calls
on this function block to change the state.
Verify that the compiler reports neither errors nor warnings when
compiling the application.
For each POU, verify that variables are not re-used later on with
a different meaning.
Verify that the names of safety POUs start with “S_”. Verify that
the names of non-safety POUs do not start with “S_”.
These rules have to be checked only if
you plan to implement not only safety
but also non-safety functions on SM560-
S Safety CPU. In typical applications
with AC500-S it is not the case, because
non-safety functions are realized on
PM5xx Non-safety CPUs.
Verify that names of safety-related local variables start with “S_”.
Verify that names of global safety variables start with “GS_”.
Verify that names of safety inputs start with “IS_”.
Verify that names of safety outputs start with “OS_”.
Verify that names of non-safety variables do not start with either
“S_”, “GS_”, “IS_” or “OS_”.
Verify that names of global variable lists containing non-safety
variables do not start with S_.
Verify that names of global variable lists containing safety varia-
bles start with S_.
For each non-safety POU, verify that it does not write to any
safety variable.
4.6 AC500-S Libraries
4.6.1 Overview
The following safety libraries are certified by TÜV and are allowed to be used with AC500-S Safety PLC:
Configuration and programming
AC500-S Libraries > Overview
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AC500-S
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