TECHNICAL
SPECIFICATION
:
IEC
TS
61508-3-1
Edition 1.0 2016-07
Functional
safety
of
electrical/electronic/programmable
electronic
safety-related
systems-
Part
3-1:
Software
requirements
-
Reuse
of
pre-existing
software
elements
to
implement
all
or
part
of
a
safety
function
TECHNICAL
SPECIFICATION
IEC
TS
61508-3-1
Edition 1.0 2016-07
Functional
safety
of
electrical/electronic/programmable
electronic
safety-related
systems
-
Part
3-1 :
Software
requirements
-
Reuse
of
pre-existing
software
elements
to
implement
all
or
part
of
a
safety
function
I
NTERNATIONAL
EL
ECTROTECHNICAL
COMM
I
SS
I
ON
I
CS
25.040.40; 35.
240
.50 ISBN 978•2·8322-3516-4
Warning!
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ist
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o
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te
rnational
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cctrotcc
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Com
mi
ssion
- 2 -
IEC
TS
61508-3-1 :
2016
©
IEC
2016
CO
NT E
NTS
FOREWORD
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Normative
References
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3
Terms
and
definitions
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4
Requirements
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Bibli
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10
IEC
TS
61508
-3-
1:2016
© IEC
2016
-3-
INTERNATI
ONAL
ELE
C
TRO
TECHNI
CAL
CO
MMI
SS
ION
FUNCTIONAL
SAFETY
OF
ELECTRICAL/ELECTRONIC
/
PROGRAMMABLE
ELECTRONIC
SAFETY-RELATED
SYSTEMS
-
Part
3-1:
Software
re
quirements
-
Reuse
of
pre-existing
software
elements
to
implement
all
or
part
of
a
safety
funct
i
on
FOREWORD
1)
The
International
Electrotechnical
Comm
i
ssion
(I
EC
) is a
worldw
i
de
organ
i
zation
for
standardizat
i
on
compr
isi
ng
all
national
electrotechnica
l
committees
(IEC
National
Committees).
T
he
object
of
I
EC
is
to
promote
in
t
ernationa
l
co-operation
on
a
ll
ques
ti
ons
concerning
standardiza
t
ion
in
the
el
ectrica
l
and
e l
ectron
ic fiel
ds.
To
th
is
end
and
in
add
iti
on
to
other
act
i
vit
i
es,
I
EC
publ
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shes
Internat
i
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ch
nical
Spec
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ficat
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Publicly
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ons
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PAS)
and
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(h
ereafter
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r
red
to
as
"I
EC
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l
icat
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on(s)")
.
Their
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i
on
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entrusted
to
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;
any
IEC
Nationa
l
Committee
i
nterested
in
t
he
subject
dealt
with
may
partic
i
pate
in
thi s
preparatory
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. In
ternational
,
governmental
and
non-
governmental
organizations
l
iaising
with
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IEC al
so
participate
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.
IEC
collaborates
closely
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In
ternational
Organizat
i
on
for
Standard
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zat
i
on
(ISO)
in
accordance
with
cond
i
tions
determined
by
agreemen
t
between
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two
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gan
izat
ions.
2)
The
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l
dec
i
sions
or
ag
r
eements
of
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on
t
echn
i
cal
matte
rs
express,
as
near
ly
as
possib
le,
an
in
ternat
i
onal
co
n
sensus
of
op
i
nion
on
the
relevan
t
subjects
since
each
tech
n
ica
l
commi
tt
ee
has
r
epresen
t
at
i
on
fr
om
all
in
t
erested
IEC
National
Committees
.
3 )
IEC
Publications
have
the
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orm
of
recommendations
f
or
internationa
l
use
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by
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EC
Nat
i
onal
Committees
in
that
sense
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Wh
il
e a
ll
reasonab
le
efforts
are
made
to
ensure
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the
techn
ical
content
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Publica
ti
ons
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accurate,
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be
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ld
respons
i
ble
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way
in
wh
i
ch
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are
used
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for
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int
erpretation
by
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end
user
.
4)
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order
to
pr
omote
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nterna
ti
ona
l
uni
f
orm
i
ty
, I
EC
Na
ti
ona
l
Comm
i
ttees
undertake
to
apply
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tran
spa
r
ently
to
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maximum
exten
t
possible
in
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and
regional
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l
ications
.
Any
di
ve
r
gence
between
any
IEC
Pub
l
ication
and
the
corresponding
national
or
regiona
l
pub
l
icat
i
on
sha
ll
be
clearly
indicated
in
the
latter.
5 )
IEC
it
se
lf
does
not
pro
vi
de
any
attestation
of
conform
i
ty.
Independent
certifica
t
ion
bod
i
es
prov
i
de
confo
r
mity
assessment
serv
i
ces
and,
in
some
areas
,
access
to I
EC
ma
r
ks
of
con
fo r
mity
. I
EC
is
not
respons
i
ble
for
any
services
carried
out
by
independent
cert
i
fication
bod
i
es
.
6 )
All
users
should
ensure
that
they
have
the
latest
edit
i
on
of
th
is
pub
l
ication
.
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No
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ili
ty
shall
attach
to
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EC
or its d i
rectors,
employees,
servants
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agents
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ng
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i
vidual
experts
and
members
of
ils
t
echnica
l
comm
i
ttees
and
IEC
Nat
i
onal
Comm
i
ttees
for
any
persona
l i
nj
ury,
proper
ty
damage
or
ot
her
damage
of
any
n
atu
re
whatsoever,
whether
direct
o r i
nd
i
rect,
or
for
costs
(i
nc
l
ud
ing
lega
l
fee
s)
and
expenses
ar
isi
ng
out
of
the
publ
i
cat
i
on,
use
of
,
or
re
l
ia
n
ce
upon
,
this
I
EC
Publ
i
cation
or
any
other
l
EC
Pub
l
ica
ti
ons
.
8)
Attent
i
on
is
drawn
to
the
Normat
i
ve
references
c
it
ed
in
this
publicat
i
on
.
Use
of
the
refere
n
ced
public
at
i
ons
is
i
nd
i
spensable
for
the
correct
appl
i
cation
of
th
is
pub
li
cat
i
on.
9)
Attention
is
drawn
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poss
ibi
li
ty
t
hat
some
of
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he
elements
of
t
his
IEC
Pub
l
ication
may
be
t
he
subjec
t
of
patent
ri
ghts.
IEC
sha
ll
not
be
held
respons
i
ble
for
i
dentifying
any
or
all
such
patent
rights.
The
mai
n t
ask
of
IEC
technical
committees
is to
prepa
re I
nternational
Standar
d
s.
In
exceptional
circumstances
, a techn
ical
committee
may
propose
the
pub
l
ication
of
a t
ec
hn
ical
speci
fi
cat
i
on
when
the
re
quired
support
cannot
be
obtaine
d
for
the
publication
of
an
I
nternat
i
onal
Standard
,
despi
te
repeated
efforts,
or
the
subj
ec
t is
still
under
technica
l
development
or
whe
r
e,
for
an
y
other
reason,
there
is
the
future
but
no
im
med
i
ate
poss
i
bility
of
an ag
r
eement
on
an
I
nterna
t
ional
Standard.
Technical
specificat
i
ons
are
subject
to
review
within
t
hree
years
of
publ
i
ca
ti
on
to d
ecide
whet
her
they
can
be
transformed
into
I
nternationa
l
Standards.
