The validation process implemented by T & T Systems covers the entire development of the system, equipment or machinery, and thanks to its skills, HINTSW - T & T Systems is able to handle all validation activities required by standards regarding the functional safety of the programmable electronic systems , such as IEC 61508, IEC 61511, IEC 50126, IEC 50128, IEC 62061, EN ISO 13849-1, IEC 60730, IEC 60601-1, and so on.
The validation activities, which are organized according to the phases of the safety life cycle (for more information see separate section of the site), concern both the Hardware and Software, and both are made according to the latest methodologies and safety engineering techniques as it is documented in the literature and prescribed by the standards
Methodologies, techniques and testing tools are described in detail in the special pages (Hardware testing; HW validation tests; HW diagnostic tests; test software) included in the section on the safety engineering. In this page, however, the organization of the validation process within the security system life cycles is described.
The activities of HINTSW - T & T Systems, according to the complexity of the system and its scope, are usually organized as follows:
- Planning of the validation process with the choice of the phases, the methodologies and the validation techniques; this activity is performed at the beginning of the safety life cycle and, depending on the case, it refers:
to the overall safety life cycle (for example, phase 7 of life-cycle proposed by IEC 61508-1); the output of this activity is the writing of the "global security validation Plan" and has the aim to validate all the safety systems in their entirety.
to the system and SW life cycles (for example, phase 9.2 of the system and SW life cycles, proposed by IEC 61508-2 and 61508-3); the output of these activities is to draw up two separate plans: "System safety validation plan" and "Software safety validation plan"; such plans are designed to validate the safety requirements allocated to the integrated safety system, hardware and software.
- Definition of test cases with the writing of the specification / protocols of the tests and with the preparation of reports related to the tests; this activity is carried out during the phases of definition of the safety requirements and, depending on the case, to all three the the safety life cycles as follows:
the overall safety life cycle: the specification of overall safety validation tests; often these tests are part of the so-called SAT (Site Acceptance Test) or UAT (User Acceptance Test), less often they are part of the so-called FAT (Factory Acceptance Test); these tests have the aim to validate the overall safety requirements and are designed in parallel to the definition of the overall safety requirements;
life cycle of the system safety: writing the specification of system security validation tests and of the specification of system integration tests; often the first test category is part of the so-called FAT (Factory Acceptance Test), it has the aim to validate the safety requirements of the system and is simultaneously designed to their definition; the second test category (integration test) is designed in parallel with the architecture definition of the system and its decomposition into subsystems, it has the aim to test the correct integration of the subsystems that make up the system;
life cycle of software safety: the software validation activities consists of following activities:
specification of software safety validation tests: it is prepared jointly with the definition of the safety requirements of the software and is designed to validate the safety requirements of the software; the tests are performed on the fully integrated system and, depending on the case, can belong both of FAT, both of SAT;
specification of hardware / software integration tests: it is written in conjunction with the architecture definition of the programmable electronics (hardware) and with the definition of the safety requirements of the software; the tests are usually performed at the end of the integration phase of the system (therefore on the already fully integrated system or pre-integrated) and their purpose is to prove that the hardware architecture meets the safety requirements of the software;
specifications of the module test (or unit tests): they are written in parallel with the drafting of the SW modules design specifications; the tests are performed at the end of each SW implementation module and have the purpose to monitor the correct implementation of the software modules.
specifications of the module test (or unit tests): are written in parallel with the drafting of the SW modules design specifications; the tests are performed at the end of each SW implementation module and have the purpose to monitor the correct implementation of the software modules.
- Esecuzione delle varie fasi di testing con la compilazione dei relativi reports; anche in questo caso le attività interessano alcune fasi specifiche dei tre cicli di vita della sicurezza:
- life cycle of software safety:
- execution of the module tests and compiling a test report for each tested module; the tests are performed at the implementation end of each module SW;
- execution of software integration tests and compilation of its report; tests are performed simultaneously with the integration of the software;
- execution of the hardware / software integration tests and compilation of its report; the tests are performed at the end of the integration of the software andthe integration of the hardware platform; that, in function of the complexity of the system, may coincide or not with the integration of the system; in more complex cases, the tests can be performed on a pre-integrated or partially integrated system;
- execution of the software safety validation test: is the phase the the most important software testing and is performed at the end of the software development cycle; usually it runs on the fully integrated system and can coincide with the FAT, or, most often, it is executed in a dedicated test phase before the execution of the FAT; in this phase the report the the validation software is prepared, this report usually contains not only the outcome of the tests, but also the evidence of all testing activities conducted on the software; for this reason this report is a major component of the safety assessment and is one of the input documents for the eventual writing of the safety case;
- life cycle of the system safety:
- execution of system integration tests and writing of the report, the tests are performed during the integration phase of the system and, depending on the case, may be carried out without help of the software, or by using specially developed software tools, or, if already provided, using the software which has at least positively overcome the phase of the SW integration tests;
- execution of the safety of the system validation tests: it is the most important testing phase of the system and it is executed at the end of the system development cycle; the tests, depending on the case, can be performed in an ad hoc phase of the system development cycle, or they can coincide with the FAT, less often they can coincide with the SAT; the tests can possibly be performed in synergy with the safety of software validation testing; in this phase it is drawn up the validation report of the system that usually contains not only the outcome of the tests, but also the evidence of all testing activities performed on the system; this is why this report is one of the main components safety assessment and is one of the input documents in the eventual writing of the safety case;
- the overall safety life cycle:
- execution of the overall safety validation tests and writing of the report; this testing phase is only carried out in cases in which the two life cycles of the safety and the overalll system do not coincide, and this usually occurs in systems and in complex applications, in which more systems interact and / or are present more safety systems , or when a safety system must be integrated into a larger and more complex system; in the context just described the tests can coincide with SAT; they are almost always carried out in field and, sometimes, they consist of the repetition of system validation tests already carried out in the factory (FAT); also in this case the overall safety validation report is one of the most important documents to be analyzed during the safety assessment and is part of the input information necessary for the writing of the safety case document