hisl_0024: Inport interface definition

R2026b

Define data type, port dimensions, and sample time for inports to support strong typing and unambiguous model behavior

Usage: High-Integrity System Modeling

Guideline ID: hisl_0024

Rules

hisl_0024: Inport interface definition

hisl_0024: Inport interface definition
To support strong data typing and unambiguous behavior of the model and the generated code, set parameters Data type, Port dimensions, and Sample time for each: Model root-level inport Signal object that explicitly resolves to a connected signal line Architecture model root-level inport port For export-function models, you can set Sample time to `-1`. Rationale Avoid ambiguous behavior. Support full specification of the software interface. Verification Check for root Inports with missing properties (Simulink Check)

To support strong data typing and unambiguous behavior of the model and the generated code, set parameters Data type, Port dimensions, and Sample time for each:

Model root-level inport
Signal object that explicitly resolves to a connected signal line
Architecture model root-level inport port

For export-function models, you can set Sample time to -1.

Rationale

Avoid ambiguous behavior.
Support full specification of the software interface.

Verification

Check for root Inports with missing properties (Simulink Check)

Tips

Using root-level Inport blocks without fully defined dimensions, sample times, or data type can lead to ambiguous simulation results.
If you do not explicitly define these parameters, Simulink back-propagates dimensions, sample times, and data types from downstream blocks.
Adhering to this guideline captures reusable specifications (for example, array of structures) as a Simulink.ValueType object and specifies the data type of the In Bus Element and Out Bus Element blocks.

Industry Standards

DO-331 Section MB.6.3.2.b 'Low-level requirements are accurate and consistent'
IEC 61508-3, Table B.9 (6) 'Fully defined interface'
IEC 62304, 5.5.3 - Software Unit acceptance criteria
ISO 26262-6, Table 1 (1a) – Enforcement of low complexity
ISO 26262-6, Table 1 (1c) – Enforcement of strong typing
ISO 26262-6, Table 1 (1f) – Use of unambiguous graphical representation
ISO 26262-6, Table 3 (1c) – Restricted size of interfaces
ISO 26262-6, Table 7 (1k) – Interface test
EN 50128, Table A.3 (19) 'Fully Defined Interface'
EN 50657, Table A.3 (19) 'Fully Defined Interface'
EN 50716, Table A.3 (17) 'Fully Defined Interface'

Version History

Introduced in R2013b

expand all

R2026a: Added EN 50657 references

The Industry Standards section has been updated to include EN 50657 references.

R2023b: Updated note with information about reusable specifications and bus element blocks

The Tips section has been updated with information about capturing reusable specifications as a Simulink.ValueType object and specifying the data type of the In Bus Element and Out Bus Element blocks.