Safety Of Electronic Control Equipment; Introduction; Reliability; Carrying Out Tests - Siemens Logo! Manual

Safety of electronic control equipment

Introduction

The notes below apply regardless of the type or
manufacturer of the electronic control.

Reliability

Maximum reliability of LOGO! devices and components is
achieved by implementing extensive and cost-effective
measures during development and manufacture.
This includes the following:
S
Use of high-quality components;
S
Worst-case design of all circuits;
S
Systematic and computer-aided testing of all
components;
S
Burn-in of all large-scale integrated circuits (e.g.
processors, memory, etc.);
S
Measures preventing static charge when handling MOS
ICs;
S
Visual checks at different stages of manufacture;
S
Continuous heat-run test at elevated ambient
temperature over a period of several days;
S
Careful computer-controlled final testing;
S
Statistical evaluation of all returned systems and
components to enable the immediate initiation of
suitable corrective measures;
S
Monitoring of major control components, using on-line
tests (cyclic interrupt for the CPU, etc.).
These measures are referred to as basic measures.

Carrying out tests

You must, however, ensure safety in your plant.
Before finally commissioning a system you should carry out
complete functional testing as well as all necessary safety
testing.
Also include in testing any predictable faults that can occur.
This means that you will avoid any danger to the plant or to
people in it during operation.
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