SM/DC configuration for DC worksheet

medini_1053080245

Hello, We have many DC worksheet that use a collection of SM to set the Diagnostic coverage of the associated Failure modes. As the design is currently on-going, we would like to have a DC worksheet (and then metrics) that evolve together with the design status. To do so, we set the DC of non-designed SM to 0% (and change it as soon as it has been developped). But it seems that the DC% in the DC worksheet keeps the native DC% (value when we first time set the SM into the DC worksheet) and seems to be not synchronized with the DC% attribute of the SM list. Is that normal? Do we use a wrong process to do so? What would be the best way otherwise?

medini_1023909254

Hello Romain, yes this is indeed intended behavior: When adding a SM for the first time to a failure, the worksheet will get initialized  with the default (nominal) coverage from the SM in the collection.  However, afterwards you can change the coverage value in the DC Sheet -  as the real coverage may depend on the failure mode itself and also on  the safety goal under investigation. A good example is usually a  periodic running SM which checks something every 100ms, if you SG has a  FTTI of 1s, of course this SM can have a very high coverage. However, if  the FTTI is just 10ms, the coverage will be much lower as you will not  be able to detect the failure always. Thus medini will  keep the coverage values in the DC and not automatically propagate  changes from the SM configuration into the DC Sheet (to avoid any  overwriting of manual changes). On the other side, in the  BestPractice Template you will also find a script  "UpdateSMCoverageInDCSheet" which can forcefully reset all the coverage  values in the DC sheet to the values from the configuration (and  overwriting thus any manual changes) - please use it carefully. BTW, the script has also a few option to determine the DC in case multiple SM are assigned. Best regards, Eckhardt