B.5 Safety Of Electronic Control Systems - Siemens Sinumerik 802D sl Instruction Manual

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B.5
Safety of electronic control systems
Introduction
The information provided here is mainly of general nature and applies irrespective of the
type of the electronic control system and its manufacturer.
Reliability
Comprehensive and cost-effective measures have been taken during development and pro-
duction to increase the reliability of the devices and components as far as possible.
These include
S the selection of high-quality components;
S worst-case design of all circuits;
S systematic and computer-controlled testing of all components delivered;
S burning in of all LSI circuits (e.g. processors, memories, etc.)
S measures preventing static charge when handling MOS ICs;
S visual checks and inspections at various stages of production;
S continuous heat testing at increased ambient temperature over several days;
S careful computer-controlled final testing;
S statistic evaluation of all returned goods for immediate introduction of corrective
S monitoring of the most important control parts by way of online tests (watch dog, etc.).
In terms of safety technology, these measures are called basic measures; they avoid or con-
trol most possible errors.
The risk
Special safety standards must be applied to any system – and therefore to the situation as
well – whenever, if a fault occurs, it may cause injury to persons or damage to property. For
these applications, special, plant-specific regulations exist which must be observed when
designing the control system (e.g. VDE 0116 for furnaces).
For electronic control systems with safety relevance, the measures to be taken to avoid or
control errors depend on the risk resulting from the plant. In this conjunction, the basic mea-
sures mentioned above are not sufficient any more for a certain hazard potential. Additional
measures (e.g. channel redundance, tests, checksums, etc.) must be implemented and cer-
tified for the control system (DIN VDE 0801).
Siemens Automation Parts
SINUMERIK 802D sl Instruction Manual (BA), 05/2005 Edition
6FC5 397-0CP10-1BA0
measures;
Standards and Approvals
B.5
Safety of electronic control systems
B-237

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