ifm
System Manual
ecomat
mobile
PDM360NG (CR1080, CR1081, CR9042) Target V01
2011-07-28
Glossary of Terms
454
Redundant
Redundancy is the presence of more than the
necessary means so that a function unit
performs a requested function or that data can
represent information.
Several kinds of redundancy are distinguished:
Functional redundancy aims at designing
safety-related systems in multiple ways in
parallel so that in the event of a failure of
one component the others ensure the task.
In addition it is tried to separate redundant
systems from each other with regard to
space. Thus the risk that they are affected
by a common interference is minimised.
Finally, components from different
manufacturers are sometimes used to
avoid that a systematic fault causes all
redundant systems to fail (diverse
redundancy).
The software of redundant systems should
differ in the following aspects:
specification (different teams),
specification
language,
programming (different teams),
programming
language,
compiler.
Remanent
Remanent data is protected against data loss
in case of power failure.
The operating system for example
automatically copies the remanent data to a
flash memory as soon as the voltage supply
falls below a critical value. If the voltage supply
is available again, the operating system loads
the remanent data back to the RAM memory.
The data in the RAM memory of a controller,
however, is volatile and normally lost in case of
power failure.
Reset, manual
The manual reset is an internal function within
the SRP/CS used to restore manually one or
more safety functions before re-starting a
machine.
Residual risk
Risk remaining after protective measures have
been taken. The residual risk has to be clearly
warned against in operating instructions and
on the machine.
Risk
Combination of the probability of occurrence of
harm and the severity of that harm.
Risk analysis
Combination of ...
the specification of the limits of the
machine (intended use, time limits),
hazard identification (intervention of
people, operating status of the machine,
foreseeable misuse) and
the risk estimation (degree of injury, extent
of damage, frequency and duration of the
risk, probability of occurrence, possibility of
avoiding the hazard or limiting the harm).
Risk assessment
Overall process comprising risk analysis and
risk evaluation.
According to Machinery Directive 2006/42/EU
the following applies: "The manufacturer of
machinery or his authorised representative
must ensure that a risk assessment is carried
out in order to determine the health and safety
requirements which apply to the machinery.
The machinery must then be designed and
constructed taking into account the results of
the risk assessment." (
Annex 1, General
principles)
Risk evaluation
Judgement, on the basis of the risk analysis, of
whether risk reduction objectives have been
achieved.
ro
RO = read only for reading only
Unidirectional data transmission: Data can only
be read and not changed.
