Programmable electronics PE

This is an electronic component or device forming part of a PE system, based on computer technology. The term encompasses both hardware and software and input and output units. 

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The safety instrumented system logic solvers addressed include Electrical (E)/Electronic (E)/ and Programmable Electronic (PE) technology. Where other technologies are used for logic solvers, the basic principles of this standard may also be applied. This standard also addresses the safety instrumented system sensors and final elements regardless of the technology used. This International Standard is process industry specific within the framework of the lEC 61508 series. 

For programmable electronic (PE) logic solvers another chart is presented in the ANSl/lSA-84.00.01-2004 (lEC 61511Mod) standard. It is shown in Figure 7-7. 

Programmable Electronic (PE) logic solvers have played an important part in process safety for thirty years. In the last decade, industry has been inundated with new terms and requirements as the functionai safety standards evolved. ANSI/ISA-84.00.01-2004-1 requires the foiiowing ... 

It should be noted that a number of the contributors to the ANSI/ISA-84.01-1996 development also worked on the ANSI/ISA-84.00.01-2004-1 development, hence the similarities. Both standards discuss the owner/operator application software used in SIS logic solvers. Neither standard addressed software development for SIL 4 SIFs, full variability languages, or embedded software (e.g., manufacturer system software for programmable electronic (PE) sensors, PE logic solvers, PE final elements). 

Requirements for Programmable Electronic (PE) logic solvers that are not designed in compliance with lEC 61508. 

ANSI/ISA 84 (3.1.56) Programmable electronics (PE) Electronic component or device forming part of a PE and based on computer technology. The term encompasses both hardware and software and input and output units. Normally these include smart sensors, PE logic solver including PLC, distributed control system (DCS), loop controller, and smart final element. 

After hazard identification, design constraints are placed and seen from the perspective of human operation, software, etc. especially for programmable electronics (PE). However, this may not completely get rid of hazards, so they are also traced at a software level. For any product safety and reliability are important issue and their intimate relationship has been explained in Fig. 111/1.9.1-1. This is standard practice in product development. 

With this evaluation of FTA concluded, an FTA in programmable electronics (PE) shall be discussed. 

One is programmable electronics (PE) (mainly logic solver), the other is non-PE devices or equipment. Here there is a point to be noted currently most of the in-stmments are smart, so they fall into type B instruments category (already discussed Clause 1.4 of Chapter VIII). There are two options for end-users to select field devices (sensors and final elements) ... 

Watch dog Combination of diagnostics and an output devices meant to monitor the correct operation of the programmable electronic (PE) devices and taking action upon detection of an in correct operation. 

These subsystems are the following the so called programmable electronics (PE), the input interfaces and output interfaces, the sensors, the actuators, and the communication links which can be of Internal use (between subsystems) or external use (with specialized peripherals, or with other PESs). Each subsystem can be split up into several elements for instance, the PE consists of a processing unit, of a memory unit, and of the Joint power supply. The assembly of a PE with the associated I/O interfaces is generally labelled as programmable controller (PC). 

It is important to note the distinction between simple (non-PES) and complex (PES) devices. This places a penalty on instruments where there is less confidence about the failure modes due to the use of programmable electronics (PES). 

Software In some programmable electronic systems (PES), errors are much easier to detect and correct than in others. Using the term software, in the wider sense, to cover all procedures, as distinct from hardware or equipment, some software is much friendlier than others. Training and instructions are obvious examples. As another example, if many types of gaskets or nuts and bolts are stocked, sooner or later the wrong type will be installed. It is better, and cheaper in the long run, to keep the number of types stocked to a minimum, even though more expensive types than are strictly necessaiy are used for some applications. 

Programmable Electronic System (PES) A system based on a computer connected to sensors and/or actuators in a plant for the purpose of control. 

The use of computers and microprocessors (also known as programmable electronic systems [PES]) in process control continues to grow. They have brought about many improvements but have also been responsible for some failures. If we can learn from these failures, we may be able to prevent them from happening again. A number of them are therefore described below. Although PES is the most precise descnption of the equipment used, I refer to it as a computer, as this is the term usually used by the nonexpert. 

A secondary goal of the standard is to enable the development of electrical/electronic/programmable electronic (E/E/PE) safety-related systems where specific application sector standards do not already exist. lEC 61511 is an industry-specific standard for the process industries that is... 

Nevertheless in the context of the licensing procedure hardwired activation of safety functions is demanded in addition to PES activation, since it is still difficult to assess the reliability of computer programs. However, in [6] aspects are presented which have to be accounted for if electric/electronic/programmable electronic systems (E/E/PES) are used to realize safety functions. Below some general remarks are made following [7]. The corresponding mathematical and technical treatment is presented in Chap. 11. Since the requirements of [6] can be applied as well to other control systems than (E/E/PES) we speak in what follows of PCE equipment with the understanding that any of the above types of process control is meant. 

Fimctional safety is a part of general safety, which depends on the proper response of the control and/or protection systems to the inpnt signals during abnormal states of a machine, installation or hazardous plant. The concept of functional safety formulated in lEC 61508 presents an example of good engineering practice applied to the design and operation of the safety-related electric, electronic and programmable electronic (E/E/PE) systems. The term safety-related applies to the systems that perform specified fiinction(s) to ensure that the risk is maintained at acceptable level. Two different requirements should be satisfied to ensure the functional safety ... 

ABSTRACT The draft document of the NATO allied ordnance publication (AOP) 52 gives guidance on software safety design and assessment of ammunition-related computing systems. The content of the draft is reviewed and compared with the lEC 61508 standard for functional safety of electrical/electronic/programmable electronic (E/E/PE) systems. We discuss the overall development model, the safety-lifecycle model and proposed techniques and measures. We also investigate whether the functional safety concept of lEC 61508 is incorporated in the document. 

This paper investigates possible relations between the AOP 52 and the standard lEC 61508 (lEC 61508 1998-2005). The lEC 61508 is a framework standard in the domain of safety-critical applications of electri-cal/electronic/programmable electronic (E/E/PE) systems. The following more domain specific standards are not considered to be suitable for comparison the lEC 61513 (lEC 61513 2002) for nuclear power plants, DIN EN 50129 (DIN EN 50129 2003) for railway applications, lEC 61511 (1EC61511 2003) forthe process industry sector and lEC 62061 (IEEE 61012-1990 1990) forthe manufacturing sector. 

The lEC 61508 is a generic standard for elec-trical/electronic/programmable electronic (E/E/PE) safety-related systems. It should be applied from the concept rmtil the disposal or decommissioning of the product if a possible failure of a system can lead to hazards for humans and/or the environment. During this product life cycle the application of the lEC 61508 is ordered using an overall safety lifecycle. The standard is a generic standard and thus is used to derive domain specific standards as described in section 1. 

Safety instrumented systems (SIS) play a major part in industrial risk management as risk reduction measures. The main European standard for functional safety of SIS, denoted electrical / electronic / programmable electronic (E/E/PE) safety-related systems, is the EC 61508 (lEC, 2005a). The second edition will soon be adopted in 2009 (EC, 2009). Objectives are to enable the design of SIS, and the development of apphca-tion sector standards. Such examples are EC 61511 (lEC, 2004) for process industry, and EC 62061 (EC 2005b) for machinery. One of the main contributions of EC 61508 is to consider the overall system and software safety life cycle. The standard fi amework, with the corresponding normative parts and subclauses, is ... 

Today s mine hoists and mine hoist brake systems are a complex combination of elec-trical/electronic, programmable electronic (E/E/PE), hydraulic and mechanical components and systems (other configurations exist). They are well designed by experienced professionals, using time tested and proven design principles and proven and reliable components. Once installed, commissioned and put into commercial operation, they are then operated and maintained by experienced operators and skilled tradespeople. Today s mine hoists and mine hoist brake systems are high performance, reliable systems with a good safety record. 

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