Ensure Interface Compatibility
The product-component interfaces, both internal and external, are compatible.
Many product integration problems arise from unknown or uncontrolled aspects of both internal and external interfaces. Effective management of product-component interface requirements, specifications, and
designs helps ensure that implemented interfaces will be complete and compatible.
SP 2.1 Review Interface Descriptions for Completeness
Review interface descriptions for coverage and completeness.
The interfaces should include, in addition to product-component interfaces, all the interfaces with the product integration environment.
Typical Work Products
1. Categories of interfaces
2. List of interfaces per category
3. Mapping of the interfaces to the product components and product integration environment
Subpractices
1. Review interface data for completeness and ensure complete coverage of all interfaces.
Consider all the product components and prepare a relationship table. Interfaces are usually classified in three main classes: environmental, physical, and functional. Typical categories for these classes include the following: mechanical, fluid, sound, electrical, climatic, electromagnetic, thermal, message, and the
human-machine or human interface.
For Software Engineering
In the message category for software, interfaces include the following:
· Origination
· Destination
· Stimulus
· Protocols and data characteristics
For Systems Engineering
For mechanical and electronic components, the interface data should include the following:
· Mechanical interfaces (e.g., weight and size, center of gravity, clearance of parts in operation, space required for maintenance, fixed links, mobile links, shocks and vibrations received from the bearing structure)
· Noise interfaces (e.g., noise transmitted by the structure, noise transmitted in the air, acoustics)
· Climatic interfaces (e.g., temperature, humidity, pressure,salinity)
· Thermal interfaces (e.g., heat dissipation, transmission of heat to the bearing structure, air conditioning characteristics)
· Fluid interfaces (e.g., fresh water inlet/outlet, seawater inlet/outlet for a naval/coastal product, air conditioning, compressed air, nitrogen, fuel, lubricating oil, exhaust gas outlet)
· Electrical interfaces (e.g., power supply consumption by network with transients and peak values; non-sensitive control signal for power supply, communications, etc.; sensitive signal [analog links]; disturbing signal [microwave,etc.]; grounding signal to comply with the TEMPEST standard)
· Electromagnetic interfaces (e.g., magnetic field, radio and radar links, optical band link wave guides, coaxial and optical fibers)
· Human-machine interface (e.g., audio or voice synthesis, audio or voice recognition, display [analog dial, TV screen, or liquid crystal display, indicators' light emitting diodes], manual controls [pedal, joystick, ball, keys, push buttons, touch screen])
2. Ensure that product components and interfaces are marked to ensure easy and correct connection to the joining product component.
3. Periodically review the adequacy of interface descriptions.
Once established, the interface descriptions must be periodically reviewed to ensure there is no deviation between the existing descriptions and the products being developed, processed, produced, or bought.
For Supplier Sourcing
The interface descriptions for product components should be reviewed with relevant suppliers to avoid misinterpretations, reduce delays, and prevent the development of interfaces that do not work properly.
SP 2.2 Manage Interfaces
Manage internal and external interface definitions, designs, and changes for products and product components.
Interface requirements drive the development of the interfaces necessary to integrate product components. Managing product and product-component interfaces starts very early in the development of the product. The definitions and designs for interfaces affect not only the product components and external systems, but can also affect the verification and validation environments.
Management of the interfaces includes maintenance of the consistency of the interfaces throughout the life of the product, and resolution of conflict, noncompliance, and change issues.
The interfaces should include, in addition to product-component interfaces, all the interfaces with the environment as well as other environments for verification, validation, operations, and support.
The interface changes are documented, maintained, and readily accessible.
Typical Work Products
1. Table of relationships among the product components and the external environment (e.g., main power supply, fastening product, computer bus system)
2. Table of relationships between the different product components
3. List of agreed-to interfaces defined for each pair of product components, when applicable
4. Reports from the interface control working group meetings
5. Action items for updating interfaces
6. Application program interface (API)
7. Updated interface description or agreement
Subpractices
1. Ensure the compatibility of the interfaces throughout the life of the product.
2. Resolve conflict, noncompliance, and change issues.
3. Maintain a repository for interface data accessible to project participants.
A common accessible repository for interface data provides a mechanism to ensure that everyone knows where the current interface data resides and can access it for use.
