Embedded Solutions CompactPCI F301-3U Manual do Utilizador descarregar pdf (Página 27)

Hardware Architectures for

Safety-Critical Applications

For the evaluation of safety it is necessary to

detect errors – redundancy is one applicable

method. The systems or part of them are du-

plicated. Only both computers combined can

set the system into the critical state. A “voter”

carries out the evaluation. If this voter detects a

difference between the two systems it sets the

system into the safe state – switches it off. This

architecture is also called “1oo2“ (1 out of 2).

This method only works in “fail-safe systems”.

In “safe operational systems” the system is kept

in the “hot standby” state. This means that a

faulty system part switches itself off and the

other part takes over its function. Now the sys-

tem is functional, but unsafe. With a 1oo2 ar-

chitecture only single faults can be detected.

With classic redundant systems and a voter

the error probability can be decreased as the

system switches into the safe state when there

To achieve a SIL 4 safety level most of the

safety measures are taken by software. On

the hardware side the systems have double

or triple redundancy. A typical “2-out-of-3“

system has three independent CPU cards with

identical I/O functions, using independent

backplanes and power supplies – all of these

components installed in the same 19“ rack. At

least two of the three computers must yield

identical results to guarantee the correct ope-

ration of the complete system.

is an error. However, availability is then de-

creased. If availability is important triple sys-

tems are often used (2oo3, 2 out of 3). Here it

is assumed that the single components are

safe. Now the voter evaluates three votes. The

majority decides. If one component delivers a

deviating result it is switched off. The system

stays safe but availability is now decreased.

With another additional computer a 2oo4

structure is achieved. When one component

fails three functional components remain – the

system is still safe and available.

6U VMEbus master/slave

2 LVDS channel links

4 MB dual-ported SDRAM

LVDS and RAM implemented in FPGA

1 ESM™ Embedded System Module slot

-5 to +70°C operating temperature

Conformal coating

No critical components (e.g. sockets)

6U CompactPCI

SBC D6

– Intel

Celeron

M, 1 GHz

– (Up to Pentium

M 2 GHz)

– PCI Express

– Up to 12 Gigabit Ethernet

– 2 XMC slots

Quad Gigabit Ethernet XMC P601

– PCI Express

2 x4

Dual HDLC/SDLC M-Module™ M75

– Optically isolated

48-bit TTL I/O PC-MIP

P13

Proprietary OS

Enlarging Availability – 2oo3 System

Custom Triple-Redundant

CompactPCI

System

for Signaling Control

.....................floating softly over the clouds............... not in the mood for waking up..............................

.................... sanft über den Wolken schweben.......... keine Lust, aufzuwachen..........................................

EN 50155 in Development

and Production

Flexible and Future-Safe

with FPGA Technology

System Solutions and

Packaging Technology

Standard Computer Boards

I/O Boards for Control and

Instrumentation

Fieldbus Solutions

Trafﬁ c Management Systems

Passenger Information Systems

Application Samples

Short Product Overview

References

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