BS/EN 16603-40-2014 pdf download.Space engineering Part 40 : Software.
4.2.1 General
In accordance with the ECSS theoretical concept, a fundamental principle of this Standard is the customer—supplier’ relationship, assumed for all software developments. The project organization is defined in ECSS-M-ST-1O. The customer is, in the general case, the procurer of two associated products: the hardware and the software for a system, subsystem. set, equipment or assembly. The concept of the “customer—supplier” relationship is applied recursively, i.e. the customer can be a supplier to a higher level in the space system. The software customer therefore has two important interfaces:
• the software customer interfaces with his software and hardware suppliers in order to adequately allocate to them functional and performance requirements. through the functional analysis.
• the software customer assumes a supplier role to interface in turn with his customer at the next higher level, ensuring that higher level system requirements are adequately taken into account.
The customer derives the tunctional and pertormance requirements tor the hardware and software, based on system engineering principles and methods. The customer can also controls the interface between the software and hardware. Software items are defined in the system breakdown at different levels. Nevertheless, it is important to manage the software—software interfaces irrespective of the level at which they occur. The customer’s requirements are specified by this process, and they provide the starting point for the software engineering.
Reviews are the main interaction points between the customer and the supplier. They also synchronize software engineering processes. The reviews relevant to the software engineering processes are the SRR, PDR, CDR, QR. AR, and ORR as defined by ECSS-M-ST-1O. This Standard offers in addition the possibility to anticipate the PDR in a SWRR, and the CDR into a DDR. The SWRR and DDR are executed as a first part of the ECSS-M-ST-1O reviews, hut precede them.
All reviews are applicable to software. The reviews occur at different levels in the customer—supplier hierarchy and are sequenced according to the overall system level planning.
The notion of engineering processes is fundamental to this Standard. The processes provide the means to describe the overall constraints and interfaces to the engineering processes at system level. At the same time, they provide the possibility to the supplier to implement the individual activities and tasks implied by the processes in accordance with a selected software life cycle. This Standard is a process model, and does not prescribe a particular software life cycle. Although the spacecraft reviews suggest a waterfall model, the software development plan can implement any lire cycle, in particular by the use of the technical reviews, less formal than the project reviews.
When the software development is included in a complete space project, the software engineering processes have also a relationship with the project phases (0, A, B, C, D, E, F) and in particular with the system level reviews (e.g. the system-software activities are executed in phase B). For other software developments which do not rely on a particular system, or which are developed for reuse, not applicable requirements can be tailored.
A software development plan defines and instantiates in details the particular implementation of this standard in a project.
Figure 4-2 identifies the main concurrent software engineering processes and shows how and when they are synchronized by the customer/supplier reviews.
4.2.2 Software related system requirements process
The software related system requirement process produces the information for input to the system requirements review (SRR). This establishes the functional and the performance requirements baseline (including the interface requirement specification) (RB) of the software development. It constitutes the link between the space system processes, as defined in ECSS-E-ST-1O and ECSSE-ST-70, and the software processes.
According to the recursive customer-supplier model of EcSS, at each level, the customer is responsible for the delivery of a system in which the developed software is integrated. According to the recursive system-subsystem model of ECSS-E-ST-1O, he is responsible for the specification of the system requirements at lower level and, in particular, for any software comprised in the system. As such, the tasks of this process are normally performed by the customer, but can be delegated to the supplier under the responsibility of the customer.
ECSS-E-ST-1O describes the following system engineering functions:
• requirement engineering, producing the system and lower level functional and technical specifications,
• system analysis, consolidating requirements through trade-off and various analysis (mission, requirement, functional, physical, performance), producing in particular the functional and physical architecture,
• system design (producing the physical architecture) and system configuration (producing the physical system with the software),
• system verification as being conformant to requirements. and
• system engineering integration and control, including in particular system integration, its relation with production, operation, product assurance and management, and the engineering database, the interface management and the technical budget management
The system engineering functions giving input to the software are the requirement engineering, the system verification and the system engineering integration and control, and clause 5.2 is organised along this line. For software, the system analysis and design only support the system requirement engineering, the system configuration includes the software development.BS/EN 16603-40-2014 pdf download.