How to determine spfTargetValue and lmpfTargetValue per SafetyGoal?

medini_1025405396

Hello,

We are trying to get the spfTargetValue and lmpfTargetValue per SafetyGoal in a script that analyzes DCWorksheets.

Starting from the DCWorksheet, we can readout the spfTargetValue and lmpfTargetValue attributes. But these attributes are individual values even if more than one SafetyGoal is analyzed in the worksheet. If the safety goals have a different ASIL, we expect different target values for each safety goal in the worksheet.

Which target value is set in the worksheet? Max over all related safety goals?

We tried as well to look into the individual safety goals (DCWorksheet.safetyGoal[]). The safety goals have as well attributes spfTargetValue and lmpfTargetValue. But these attributes seem not to be set in the safety goal objects.

In the end, we now read out the ASIL of the safety goals and we implemented our own lookup to determine the individual targets from the ASIL.

Is there another (simpler) way of doing this?

Greetings from Hamburg

Ralph

medini_1023909254

Hello Ralph,

you would need to differentiate the cases whether or not you have individual metrics enabled:

Without individual metrics:

When you create the DC Worksheet and select multiple safety goals, the spfTargetValue and lmpfTargetValue properties of the DCWorksheet are set to the maximum value of the spfTargetValue/lmpfTargetValue of all selected safety goals. These max values are also used in the Metrics view of the Worksheet as expected value.:

In case you add another safety goal later on (or change the target value of an individual goal at the DC coversheet) you need to manually push the new max value to the target value of the DC worksheet:

A mismatch of the target values of the Safety Goals and the target value of the DC Worksheet is also shown by Validation rule #0051:

With individual metrics:

In this case the property individualMetrics of the DC Worksheet is set to true. The coversheet does in that case also not show anymore the max values of the spf/lf target values for the individual safety goals. The target values for the metrics are now the individual target values for the safetygoals (as shown in the table):

These target values are used in the metrics view:

For Scripting you can access these values by selecting first the individual safety goal from the DCWorksheet property safetyGoal (which is the list of all safety goals for the sheet) and reading out the spfTargetValue / lmpfTargetValue for the goal. Note, if you did not set any value for the targets manually, you will get the default target values as defined in ISO26262 (even though the attribute view shows you  <undefined>). 

However, if you manually modify the target value (e.g. at the DC Coversheet), you will of course obtain this modified value (you would also see it in the attribute view) ... and it is of course also used in the metrics view.

Changes in the target values which deviate from the default settings are highlighted on the worksheet cover page. Also note, as the target values are stored at the safety goal, a change of the target values in one DC sheet does also apply to any other sheet where the SG is used.

Best regards,

Eckhardt