Control Systems Design Part: FS Slovak University of Technology Faculty of Material Science and Technology in Trnava 2007

Functional Specification Purpose General guidelines Ambiguity, duplication and contradiction has to be avoided All limitation should be explicitly defined Consistent and intuitive naming has to be used Each function and facility has to be testable Each specification should be traceable (traceability matrix)

Functional Specification Introduction Author of the document, his authority and for what purpose the document has been produced The contractual.status of the document Relationship to other documents

Functional Specification Overview Key objectives and benefits Reference to relevant standards and regulations High level description The main interfaces from the system to other systems or the environment

Functional Specification Overview - continued Assumptions: it defines any design or implementation assumptions or limitations as use of standard packages, program libraries, operating systems, hardware... Non-conformance with User Requirements Specification; any divergence between the Functional Specification and the User Requirements Specification has to be noted.

Functional Specification Functions The objective of the function or facility, and the details of its use, including interface with other parts of the system. Critical calculation and algorithms has to highlighted. Performance, response and accuracy Safety and security: action in case of HW/SW failures, I/O variables checking, redundancy, access restrictions, self diagnostic, data recovery, time-outs...  Functions which are configurable and any limits within which the configuration can take place  Traceability to specified requirements in User Requirements Specification

Functional Specification Functions - continued Functions which are configurable and any limits within which the configuration can take place Traceability to specified requirements in User Requirements Specification

Functional Specification Data Data definition in a hierarchical manner with complex objects being built up from simpler objects. Critical parameters has to be highlighted. Data access (which subsystems need read or write, access to each data item, access method, speed and update time, read/write interlocks) Data capacity, retention time, and details about data archiving Data integrity and security

Functional Specification Interfaces Interface with users is defined by terms as operator, administrator, system manager. Topics to consider include facilities available, types of peripherals, general format of displays and reports, error handling and reporting Interface with other systems; nature of the interaction, and the methods and rules governing the interaction

Functional Specification Interfaces - topics Data transmitted and received Data type, format, ranges, and meaning of values Timing Rate of data transfer Communications protocol – initiation and order of execution Any data haring, creation, duplication, storage, or destruction

Functional Specification Interfaces - topics continued Mechanism for invocation and interruption Communication through parameters, common data areas, or messages Direct access to internal data Error handling, recovery, and reporting Security

Functional Specification Non-functional Attributes Availability – reliability, redundancy, error checking, stand-by operation Maintainability – expansion and enhancement possibilities, spare capacity, likely changes in environment, lifetime.

Functional Specification Glossary Section This Section contains definitions or explanations of any terms that may be unfamiliar to the readership of the document