Safety Concept Diagrams

An Safety Concept Diagram is a diagram for designing concepts for safety architecture design.

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Diagram Elements in a Safety Concept Diagram

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Description of each icon

Type

Icon

Description

Select

select_icon

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.)

Requirement

requirement_icon

Add a Requirement. It creates Requirements containing SG, FR, FSR, TSR, HWSR, SWSR, or NFSR stereotypes defined beforehand by the tool.

Requirement Group

requirement_group_icon

Add a Requirement group. It creates Requirements containing SM, IF, or IF/SM stereotypes defined beforehand by the tool.

Element

element_icon

Add an Element.

Interaction

interaction_icon

Add an Interaction

System Boundary Interaction

physical_interaction_icon

Add a System Boundary Interaction

Requirement Group Pairing

req_group_pairing_icon

Add a Requirement group pairing.

Constraint Pairing

req_anchor_icon

Add a Constraint pairing.

Refer to Common Diagram Elements for information on other items.


Decomposition

Decomposition is expressed using Requirements, Requirement groups, Requirement group pairings and Constraint pairing.

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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.

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Each Requirement group indicates the providing protection or receiving protection.

Associate the Requirement “FR-100” with the Requirement group “Intended Function” using a Constraint pairing.
Associate the Requirements “FSR-001” and “FSR-002” that have just been added as the safety measure with the Requirement group “SM-001” using a Constraint pairing.
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Decomposition is performed by associating two Requirement groups with a Requirement group pairing line.

  1. 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.

  2. Select the post-decomposition ASIL to be assigned to the Requirements in each Requirement group.

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  3. 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.

  4. Decomposition is expressed by this series of operations.

    Each diagram can be edited for the Requirement ASIL, rename, etc. after decomposition.

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Requirement

Creating a Requirement

Click the requirement_icon [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.

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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.
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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.
  1. Select requirement_icon [Requirement] in the Tool Bar.

  2. 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.
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  • 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.
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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.

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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.

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Editing the ASIL

Double click the ASIL in the diagram. This can also be edited in the “Base” tab of the Properties.

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Adding a Stereotype

Add a stereotype from the [Stereotype] tab of the Requirement properties.

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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.

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Requirement Group

Creating a Requirement Group

Create a Requirement group by clicking the requirement_group_icon [Requirement Group] button on the Tool Bar.

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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.
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Editing the Requirement Group

Editing the ID

Editing the Name


Elements

Creating an Element

Create an Element by clicking the element_icon [Element] button on the Tool Bar. Alternatively, drag and drop an Element from the structure tree to the desired position on the diagram.

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A sub-element can be created inside the existing element in the Safety Concept Diagram.

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Editing the Element

Editing the ID

Editing the Name

Checking the ASIL

The list of ASILs assigned from Requirements in an element can be checked by selecting the “Base” tab - “ASIL” in the properties.


Interactions

Creating an Interaction

Select interaction_icon [Interaction] on the Tool Bar and select two Requirements as the output source and output destination of the Interaction.

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Highlighting Interactions

When selecting a Requirement diagram element on the diagram, the Interactions connected to the Requirement are highlighted.

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Editing the Interaction

Editing the ID

Editing the Name


System Boundary Interactions

Creating a System Boundary Interaction

Select physical_interaction_icon [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)

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Creating a System Boundary Interaction in the output direction

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Creating a System Boundary Interaction in the input direction

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Editing the System Boundary Interaction

Editing the ID

Editing the Name


Requirement Group Pairings

Creating a Requirement Group Pairing

Select req_group_pairing_icon [Requirement Group Pairing] on the Tool Bar and then select the two Requirement groups to be paired.

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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.

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Editing the Requirement Group Pairing

Editing the ID

Editing the Name


Constraint Pairing

Creating a Constraint Pairing

Select the req_anchor_icon [Constraint Pairing] button on the Tool Bar and select the Requirement, Requirement group, or Requirement group pairing to which to assign the Constraint pairing.

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You can create the Constraint Pairings all at once to connect the selected multiple Requirements with the Requirement groups.

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After

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Editing the Constraint Pairing

Editing the ID

Editing the Name