Decomposition

You can represent the decomposition using Requirements, Requirement Group and Requirement Group pairing.

For example, regarding the design shown above, there is a possibility of malfunction that could occur from wrong transmission of the “Send Position” request or its loss signal. So we can design the SM-001 (Safety Mechanism 001) that we implement dual detection systems and add priority judgement as below:
SCDL-Decomposition-Sample

Create a “Intended Function” Requirement Group and associate it with “FR-100” Requirement with Constraint-pairing.
Also, create another Requirement Group and let it associated with newly added “FSR-001” and “FSR-002” requirements that are included in the new SM-001.
SCDL-Decomposition-Sample

You can decompose by pairing these two Requirement Groups with “Requirement Group Pairing”.

  1. Add a Requirement Group Pairing between “Intended Function” and ”SM-001”. [Select ASIL] dialog opens.
  2. Select ASIL that you’d like to assign to Requirements in each Requirement Group.
    Assign ASIL
  3. Now create a Requirement that all the requirements in both Requirement Groups do not disturb other requirements. And add the Requirement to the Requirement Group with [Constraint Pairing].
    Safety Concept Diagram Decomposition

This is how decomposition works.
After decomposing, you can still change the Requirement’s ASIL and names.