IEC. INTERNATIONALE. INTERNATIONAL. ELECTROTECHNICAL. COMMISSION. Functional safety of electrical/electronic/ programmable electronic . January Price Group 19 IS/IEC CONTENTS Page Clause 1 Scope • ^ 2 Nomnative references 3 3 Definitions and abbreviations • 3 Annex. 13 Sep IS/IEC Functional safety of electgrical/electronic/programmable electgronic safety-related systems, Part 7: Overview of techniques and.

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The relative independence with regard to method allows users a great deal of freedom but also gives them little of the specialised support necessary when creating specifications. General requirements lEC In iec 61508-7 to a walk-through, the author is passive and the inspector is active iec 61508-7 the inspection procedure.

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System Structure for 61508-77 Fault Tolerance. To analyse a system design, by examining all possible sources of failure of a system’s iec 61508-7 and determining the effects of these failures on the behaviour and safety of the system. Iec 61508-7 static analysis is reproducible.

Wagner, Elektronik 32, H. For undated references, the latest edition of the normative document referred to applies.


In order to be able to show the development care, and in order to guarantee the verification of the evidence of safety at any iec 61508-7, special importance is given to the documentation. NOTE 2 An alternative is to demonstrate statically that memory will be adequate in all cases. The temperature is iec 61508-7 and forced-air cooling is introduced if the temperature is higher than a specified limit.

This article relies largely or entirely on a single source. Animation can give extra confidence that the system meets the real requirement as well as the specified requirement. To check the dynamic behaviour under real functional iec 61508-7, To reveal failures to meet functional specification, and to assess utility and robustness, Description; The functions iec 61508-7 a system or program are executed in a specified environment with specified test data which is derived systematically from the specification according to established criteria.

In the first run, the cells are inspected in ascending order: Lecture Notes in Computer Science, Vol. Jackson, Addison Wesley, The resulting system model is augmented with structured descriptions of all the processes in the model and the whole is then transformed into programs that will operate in the target software and hardware environment. Their main features are the following: Because iec 61508-7 number of dynamic variables and objects, and the existing free rriemory space iec 61508-7 allocating new dynamic variables iec 61508-7 objects, depends on the state of the system at the moment of allocation it is possible for faults to iec 61508-7 when allocating or using the variables or objects.


Properties, analysis and applications. To monitor the behaviour and the plausibility of the program sequence.

Preferably, detailed functional block, circuit and wiring iec 61508-7 are used in order to describe the location and lype of fault and how it is introduced; for example: To capture these models, the technique combines a number of other well-known techniques: The technique provides continuity monitoring and a higher level of confidence in the transmitter, reducing the necessary proof-test frequency of the transmitter sensing function.

This feature iec 61508-7 proven to be very useful in the specification of requirements of systems which operate in a time continuous environment. IEEE 77 4, April Like all design, it is an iterative procedure with early attempts refined in stages to produce the final diagram. The aim is to determine whether the functional unit carries out correctly iec 61508-7 the functions required by the specification, The technique of forming equivalence classes is an example of the criteria for blackbox test data.

This technique structures the functional specification into partial requirements such iec 61508-7 the simplest possible, visible relations exist between the latter. This overview describes five structured methods in more detail: This iec 61508-7 formal design and formal coding techniques. This procedure protects iec 61508-7 input and output information from both systematic and random hardware failures.

To monitor the secondary voltages and initiate a safe condition if the voltage is not in its specified range. The failure detection is realised entirely by additional software functions which perform self-tests using at least two complementary data patterns for example 55hex and AAhex.


Many of the questions are of a general nature and iec 61508-7 assessor must interpret them as seems most appropriate to the particular system being assessed. To aid in the analysis of events, or combinations of events, that will lead to a hazard or serious consequence. Some examples of static analysis, for hardware and software, are consistency analysis of the data flow such as testing if a data object is interpreted everywhere as the same value ; control flow analysis such as path determination, determination of non-accessible code ; interface analysis iec 61508-7 as investigation of variable transfer between various software modules ; dataflow analysis to detect suspicious sequences 61508–7 creating, referencing and deleting iec 61508-7 testing adherence to specific guidelines for example creepage distances and clearances, assembly distance, physical unit arrangement, mechanically sensitive physical units, exclusive use of the physical units which were introduced.

To 611508-7 the problems caused by accessing data without first checking range and type of the pointer. A set of guidelines for the development of vehicle iec 61508-7 software was published in November Equally, it is possible to work in a bottom-up fashion, combining processes and deducing the iec 61508-7 of the resulting system using inference rules related to the composition rules.

IEC Functional Safety – Standards

Overview of immunity tests. The fans 6150-7 monitored for correct operation. For example, where a self-test routine is provided to detect hardware faults, if no hardware failure occurs within the operating period, iec 61508-7 cannot consider the self-test routine for fault detection as being proven by use.

Two processing units exchange data including results, intermediate results and test data reciprocally. To iec 61508-7 the correct sequence of the individual program sections. Structured methods are essentially ‘thought tools” for iec 61508-7 perceiving and partitioning a problem or system. It is intended to 61580-7 the development of software for railway control and protection including communications, signaling and processing systems.

To lest the cases specified during worst-case analysis.