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This is the web edition of the original ‎⮫ AC500-S safety user manual, version 1.3.2. This web edition is provided for quick reference only. The original safety user manual must be used to meet functional safety application requirements.

Instead of manually checking the safety programming guidelines, you can use ABB software tool "AC500-S Safety Code Analysis" (SCA) to automatically check most of the safety rules.

When a new safety project is created in Automation Builder or when a safety project is modified, a warning message appears prompting the user to check the safety project with the SCA tool.

  1. Open the SCA tool. Either from the context menu of the safety application node or from the messages window.

    SCA_open_tool_out_of_AB

  2. With Automation Builder version < 2.6.0, SCA tool must be installed as a stand-alone tool.

    It can be downloaded for free from ‎⮫ www.abb.com/plc.

    The installation of the stand-alone SCA tool is described ‎⮫ here.

  3. Follow the described workflow in the integrated help of SCA tool to check your safety project.

  4. In Automation Builder, confirm the successful check with the SCA tool.

    SCA_confirm_check_in_AB
    SCA_confirmation_message

  5. Do the manual checks. There are rules which still have to be checked manually⮫ Table 1055 “Safety programming rules to be checked manually”. AC500-S SCA tool is not able to detect them in the safety application program.

Table 1055: Safety programming rules to be checked manually

Rule for manual check in AC500-S Programming Tool

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⮫ “SF_WDOG_TIME_SET”

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 ⮫ “Checklist for creation of safety application program”

For each POU, verify that there are no unnecessary state variables.

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 AC500-S safety CPU. In typical applications with AC500-S it is not the case, because non-safety functions are realized on non-safety CPUs.

Verify that names of safety 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 variables start with S_.

For each non-safety POU, verify that it does not write to any safety variable.