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Fault tolerance software redundancy

Software fault tolerance For software, fault tolerant design redundancies are required to mask residual design faults. Some of the issues related to this shall include but are not limited to ... [Pg.818]

Several of FM s Loss Prevention Data Publications (1, 17B, 17C) discuss the concept of triply-redundant, fault-tolerant, high-reliability hardware/software systems for manufacturing operations. Risk analysis and systems reliability research is currently underway to develop better guidelines for the design and application of reliable process control systems. [Pg.132]

The 3051S SIS has a 61508 assessment certificate states that the product can be used in SIL 2 applications as a single transmitter and SIL 3 applications if more than one transmitter is used in an identical redundant (hardware fault tolerance > 0) architecture. This helps point out the differences between random and systematic failures. The design process used to create the transmitter and its software met the more rigorous criteria of SIL 3. The chance of a systematic fault is lower. [Pg.136]

This contribution has shown the recent advancements of the software tool S yRelAn and underlying methodology, which can be utilized in the pre-design of fault-tolerant systems within the context of rehability analysis and redundancy management. The hybrid system model forms the basis of this reliabihty analysis, consisting of an upper-level Reliability Block Diagram and a lower-level Concurrent Finite State Machine environment. [Pg.1530]

Tolerate the Hazard. The design needs to be fault tolerant. That means, in the presence of a hardware/software fault, the software still provides continuous correct execution. Consider hazard conditions to software logic created by equipment wear and tear, or unexpected failures. Consider alternate approaches to minimize risk from hazards that cannot be eliminated. Such approaches include interlocks, redundancy, fail-safe design, system protection, and procedures. [Pg.53]

Design diversity This approach is rather costly. It combines hardware and software fault tolerance in different sets of computing channels. Each channel is developed in different hardware and software in redundant mode to provide the same function. This method is deployed to identify deviation of a channel from the others. The goal is to tolerate both hardware and software design faults [7]. After developing a fault tolerant design it is necessary to validate it from a reliability point of view, discussed later. [Pg.820]

Defects or faults in any component of the loop can develop into malfunctions. Faults are not always visible to the operator immediately, but may appear in such a way that they give rise to complete loop failure. In safety-critical applications, no failure can be tolerated [3]. Redundancies in hardware and software facilitate fault recovery. So, for increased dependability fault tolerant control (PTC) is an ideal solution. In critical controls it may be disastrous to tolerate any failure of control systems. In PTC the system continues to operate with single failure in components and/or subsystems. Also in cases of critical controls, FTC will make a controlled shutdown to a safe state in a critical situation. FTC systems use the help of redundancies in hardware and software, discussed earlier, and fault diagnostics and intelligent software to monitor health and behavior of components and function blocks and take remedial action. With these tools the faults are isolated and suitable... [Pg.820]

Hardware failure and software failure are two kinds of failures encountered in programmable systems, as already discussed. In cases of hardware failure, fault tolerant designs such as redundancy could be applied. Software failure, as discussed, has to overcome certain procedures, but certain failures (design failure) could include behaviors that can be unsafe. A new technique known as system theoretic process analysis is applied in nuclear installations. This is required to identify the control requirements and then check conditions caused hy inadequate control actions such as ... [Pg.890]

Various types of ship-control systems are used in submarines. The ship-control system used in the Seawolf submarine represents the state of the art for such sysfems. This sysfem incorporates various features, including a fault-tolerant computer, automatic modes of control for steering, and flat-panel operator displays [23]. High-speed data buses permit the ship control to interface effectively with the data distrihution system, gyrocompass inertial sensors, and the combat system. Furthermore, hardware redundancy and performance-monitoring software permit the system to function after experiencing malfunctions of ship sensors, control electronics, and the actuation systems it controls. [Pg.83]

After the occurrence of a failure, a totally separate computer is employed to carry out fault localization, which allows effective repair and restoration of full redundancy. The performance-monitoring software executes on the system s fault-tolerant computer and makes use of sensor voting and system mathematical models to detect failures. Real-time diagnostic tests are activated to identify suitable data paths and collect data required to carry out fault localization. [Pg.83]


See other pages where Fault tolerance software redundancy is mentioned: [Pg.219]    [Pg.132]    [Pg.253]    [Pg.36]    [Pg.16]    [Pg.1]    [Pg.123]    [Pg.136]    [Pg.1588]    [Pg.3574]    [Pg.814]    [Pg.814]    [Pg.818]    [Pg.823]    [Pg.109]    [Pg.26]    [Pg.27]    [Pg.45]   
See also in sourсe #XX -- [ Pg.814 , Pg.815 ]




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