<s>
Unified	B-Application
Diagnostic	I-Application
Services	I-Application
(	O
UDS	O
)	O
is	O
a	O
diagnostic	O
communication	O
protocol	O
used	O
in	O
electronic	B-Device
control	I-Device
units	I-Device
(	O
ECUs	O
)	O
within	O
automotive	O
electronics	O
,	O
which	O
is	O
specified	O
in	O
the	O
ISO	O
14229-1	O
.	O
</s>
<s>
It	O
is	O
derived	O
from	O
ISO	O
14230-3	O
(	O
KWP2000	O
)	O
and	O
the	O
now	O
obsolete	O
ISO	O
15765-3	O
(	O
Diagnostic	O
Communication	O
over	O
Controller	B-Protocol
Area	I-Protocol
Network	I-Protocol
(	O
DoCAN	O
)	O
)	O
.	O
</s>
<s>
By	O
now	O
this	O
communication	O
protocol	O
is	O
used	O
in	O
all	O
new	O
ECUs	O
made	O
by	O
Tier	O
1	O
suppliers	O
of	O
Original	O
Equipment	O
Manufacturer	O
(	O
OEM	O
)	O
,	O
and	O
is	O
incorporated	O
into	O
other	O
standards	O
,	O
such	O
as	O
AUTOSAR	B-Application
.	O
</s>
<s>
The	O
ECUs	O
in	O
modern	O
vehicles	O
control	O
nearly	O
all	O
functions	O
,	O
including	O
electronic	O
fuel	O
injection	O
(	O
EFI	O
)	O
,	O
engine	B-Device
control	I-Device
,	O
the	O
transmission	O
,	O
anti-lock	O
braking	O
system	O
,	O
door	O
locks	O
,	O
braking	O
,	O
window	O
operation	O
,	O
and	O
more	O
.	O
</s>
<s>
In	O
contrast	O
to	O
the	O
CAN	B-Protocol
bus	I-Protocol
protocol	O
,	O
which	O
only	O
uses	O
the	O
first	O
and	O
second	O
layers	O
of	O
the	O
OSI	O
model	O
,	O
UDS	O
utilizes	O
the	O
fifth	O
and	O
seventh	O
layers	O
of	O
the	O
OSI	O
model	O
.	O
</s>
<s>
0x29	O
0x69	O
Authentication	O
An	O
update	O
(	O
2020	O
)	O
of	O
the	O
standard	O
added	O
this	O
service	O
to	O
provide	O
a	O
standardized	O
approach	O
to	O
more	O
modern	O
methods	O
of	O
authentication	O
than	O
are	O
permitted	O
by	O
the	O
Security	O
Access	O
(	O
0x27	O
)	O
service	O
,	O
including	O
bidirectional	O
authentication	O
with	O
PKI-based	O
Certificate	O
Exchange	O
.	O
</s>
