Safety Concept Diagrams¶
An Safety Concept Diagram is a diagram for designing concepts for safety architecture design.
Diagram Elements in a Safety Concept Diagram¶
The basic operations of the Diagram Editor can be executed in this mode.This selects all diagram elements (Requirements, Requirement groups, Elements, Interactions, System Boundary Interactions, notes, etc.)
Add a Requirement. It creates Requirements containing SG, FR, FSR, TSR, HWSR, SWSR, or NFSR stereotypes defined beforehand by the tool.
Add a Requirement group. It creates Requirements containing SM, IF, or IF/SM stereotypes defined beforehand by the tool.
Add an Element.
Add an Interaction
System Boundary Interaction
Add a System Boundary Interaction
Requirement Group Pairing
Add a Requirement group pairing.
Add a Constraint pairing.
Refer to Common Diagram Elements for information on other items.
Decomposition is expressed using Requirements, Requirement groups, Requirement group pairings and Constraint pairing.
In the design shown above, the “position transmission” requirement may be subject to malfunction in the event of mistransmission or a loss of signal. To prevent this, SM-001(Safety Mechanism 001) is considered. As shown in the figure below, the position detection function and transmission method are duplicated and the “ON” status is judged to have higher priority.
Each Requirement group indicates the providing protection or receiving protection.
Decomposition is performed by associating two Requirement groups with a Requirement group pairing line.
Create the Requirement group pairing line between the Requirement groups “Intended Function” and “SM-001”. The dialog is displayed to specify decomposition. The ASIL Requirement selected in “Decomposition Target Requirement” is used as the pre-decomposition ASIL.
Select the post-decomposition ASIL to be assigned to the Requirements in each Requirement group.
Next, set a Requirement that the Requirements in each Requirement group do not interfere with other Requirements, and associate this Requirement and the Requirement group pairings using a Constraint pairing.
Decomposition is expressed by this series of operations.
Each diagram can be edited for the Requirement ASIL, rename, etc. after decomposition.
Creating a Requirement¶
Click the [Requirement] button on the Tool Bar or double click the Safety Concept Diagram.
The current stereotype is applied to the Requirement created by double-click on a diagram.Requirements containing SG, FR, FSR, TSR, HWSR, SWSR, or NFSR stereotype defined beforehand by the tool can be created by clicking the [Requirement] button on the Tool Bar.The currently selected stereotype is displayed on the right of the pull-down button.
Insert a Requirement in the Interaction¶
The newly created Requirement can be inserted in the Interaction.The procedure below describes how to insert a new Requirement in the Interaction created between two Requirements.
Select [Requirement] in the Tool Bar.
Mouse over the Interaction and click on the highlighted Interaction.
The connection method between the Interaction and new Requirement changes depending on the clicking position.
- Clicking on the start side of the Interaction reconnects the start side of the Interaction to the newly inserted Requirement.In addition, a new Interaction is created with the inserted Requirement as its end side.The guideline is that the start side of the existing Interaction is highlighted in a round shape as shown in the figure below.
- Clicking on the end side of the Interaction reconnects the end side of the Interaction to the newly inserted Requirement.In addition, a new Interaction is created with the inserted Requirement as its start side.The guideline is that the end side of the existing Interaction is highlighted in a round shape as shown in the figure below.
Editing the Requirement¶
Editing the ID¶
Double click the ID in the diagram and edit it by direct entry. This can also be edited in the “Base” tab of the Properties.
Editing the Name¶
Double click the name in the diagram and edit it by direct entry. This can also be edited in the “Base” tab of the Properties.
Editing the ASIL¶
Double click the ASIL in the diagram. This can also be edited in the “Base” tab of the Properties.
Adding a Stereotype¶
Add a stereotype from the [Stereotype] tab of the Requirement properties.
List of the Assigned ASILs¶
You can see the list of ASILs assigned to the Requirements by [ASIL history] in the requirement context menu on the Diagram.
The ASIL currently set in the Requirement is displayed with blue background.
Creating a Requirement Group¶
Create a Requirement group by clicking the [Requirement Group] button on the Tool Bar.It creates Requirement groups containing SM, IF, or IF/SM stereotypes defined beforehand by the tool.The currently selected type of the Requirement group is displayed on the right of the pull-down button.
Creating an Element¶
Create an Element by clicking the [Element] button on the Tool Bar. Alternatively, drag and drop an Element from the structure tree to the desired position on the diagram.
A sub-element can be created inside the existing element in the Safety Concept Diagram.
Creating an Interaction¶
Select [Interaction] on the Tool Bar and select two Requirements as the output source and output destination of the Interaction.
When selecting a Requirement diagram element on the diagram, the Interactions connected to the Requirement are highlighted.
System Boundary Interactions¶
Creating a System Boundary Interaction¶
Select [System Boundary Interaction] on the Tool Bar.
To create a System Boundary Interaction in the output direction, select an area on the diagram that is parallel to the Requirement to be set as the output destination of the System Boundary Interaction.
To create a System Boundary Interaction in the input direction, select an area on the diagram that is parallel to the Requirement to be set as the input destination and then select the Requirement to be set as the input destination.
System Boundary Interaction (Output Direction)
Creating a System Boundary Interaction in the output direction
Creating a System Boundary Interaction in the input direction
Requirement Group Pairings¶
Creating a Requirement Group Pairing¶
Select [Requirement Group Pairing] on the Tool Bar and then select the two Requirement groups to be paired.
A Requirement with ASIL A or higher needs to be set to the Requirement group in order to create a Requirement pairing.
Refer to Decomposition for details.
The dialog is displays as below and decomposition can be executed.
Creating a Constraint Pairing¶
Select the [Constraint Pairing] button on the Tool Bar and select the Requirement, Requirement group, or Requirement group pairing to which to assign the Constraint pairing.
You can create the Constraint Pairings all at once to connect the selected multiple Requirements with the Requirement groups.