Glossary · Engineering, integration and validation
Design specification
Also known as: Detailed design specification, DDS
German: Entwurfsspezifikation
In automation and software engineering, a design specification describes how a system will be built to meet its functional specification: architecture, hardware and software modules, interfaces, data structures and algorithms. It is the basis for implementation and for detailed tests.
- Validation
In one sentence
A design specification describes how a system is built to meet its functional specification: architecture, modules, interfaces and data.
Example
The design specification for the palletizer defines the function block structure, the PROFINET device names and the data exchange with the warehouse system.
How it applies
- Engineering: The design specification refines the Functional specification into implementable decisions: controller architecture, software modules, Interface specifications, naming conventions and data types.
- Testing: In a V-model, design specifications are verified by module and integration tests, while the functional specification is checked in the Factory acceptance test (FAT).
- Maintenance: Service engineers use the design specification to understand the structure of the software before they modify it.
- Documentation: The documentation team keeps each design specification traceable to the requirements it implements and flags design decisions that users must know about, such as limits or fixed parameters, for the user documentation.
Design specification vs. functional specification
The Functional specification says what the system does, from the user's and process view. The design specification says how it does it technically. In regulated environments following GAMP-style life cycles, the two are often separate, approved documents with separate verification activities.