DNP3 adv

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Comparison
of
DNP3
and
IEC
61850
communication
protocols

Enrique
Quintero

Abstract

In
today’s
world,
there
are
many
choices
for
implementing
a
supervisory
data
and
control

protocol
in
the
field
making
it
difficult
to
select
the
proper
supervisory
data
and
control

protocol
for
a
specific
application.
Nowadays,
all
supervisory
data
and
control
protocols
have

advantages
and
disadvantages
that
allows
engineers
to
have
a
general
idea
regarding
how
a

supervisory
data
and
control
protocol
works.
This
paper
will
give
you
a
general
insight
on
the

operation
of
DNP3
and
IEC
61850
as
well
as
the
general
idea
of
some
similarities
and

differences
by
comparing
DNP3
and
IEC
61850
protocols
which
so
far
are
the
most
popular

protocols
accepted
in
the
industry.



Introduction

The
boom
of
technology
was
taking
place
during
the
1970’s.
During
this
time
utility
industries

began
to
see
the
need
to
have
systems
that
could
be
monitored
and
controlled
without
human

intervention.
As
a
result,
many
companies
began
inventing
their
own
data
communication

protocols
(close
protocols)
that
fulfilled
that
need.
The
idea
was
very
successful
until
the

companies
started
to
realize
that
having
only
one
specific
communication
protocol
that
was

device
specific
was
not
very
efficient.
The
lack
of
compatibility
between
protocols
and
devices

ended
with
an
interoperability
problem
of
data
communication
protocols.
A
few
years
later,

industry
and
vendors
recognized
the
problem
and
started
proposing
solutions
to
the

interoperability
problem
until
they
arrived
at
a
final
solution.
So,
in
1985
vendors
and

organizations
dedicated
to
the
advancement
of
technology
such
as
Institute
of
Electrical
and

Electronics
Engineers
(IEEE),
Electric
Power
Research
Institute
(EPRI)
and
International

Electrotechnical
Commission
(IEC)
had
several
meetings
with
the
main
objective
of
discussing

the
interoperability
problem
in
data
communication
protocols.
The
conclusion
of
these

meetings
was
that
communication
protocols
for
real
time
data
needed
to
be
standardized.
In

1988,
the
first
standardized
protocol
emerged
which
was
the
IEC
870.
In
1990
taking
the
IEC

870
protocol
as
the
basis,
three
paths
took
place
in
parallel.
The
first
path
developed
what
we

know
today
as
utility
communication
architecture
(UCA)
and
IEC
61850,
the
second
path

developed
what
we
know
today
as
IEC
60870,
and
the
third
path
developed
what
we
know

today
as
Distributed
Network
Protocol
version
3
(DNP3).
As
a
result,
the
standardization
of

communication
protocols
started
its
long
journey.
Today
communication
protocols
are

compatible
with
various
devices
from
different
manufactures.




IEC
61850
(Generic
Object
Oriented
Substation
Event)
protocol

IEC
61850
(GOOSE)
is
an
unsolicited
event‐driven
peer‐to‐peer
communication
protocol
that

defines
communication
between
one
UCA
compliant
Electronic
Intelligent
Device
to
another

UCA
compliant
Electronic
Intelligent
Device.
IEC
61850
is
a
collection
of
standards
with
the
main

objective
of
being
compactible
with
many
third
party
applications.
IEC
61850
has
standardized

names,
meaning
of
data,
abstract
services,
and
device
behavior
model.
In
IEC
61850
all
mapping

of
abstract
services
and
models
are
specifically
for
control
and
monitoring,
protection,
and

transducers.
In
IEC
61850
protocol,
the
publisher
broadcast
a
GOOSE
message
to
all

subscribers.
When
the
subscriber
sees
the
message
it
has
two
options:
captures
the
message
or

ignore
it.
In
IEC
61850
all
data
is
originated
at
the
source
which
helps
the
implementation
by

minimizing
wiring.

IEC
61850
(GOOSE)
Layers



IEC
61850
(GOOSE)
layered
architecture
is
conformed
according
to
the
Utility
Communication

Architecture
(UCA).
The
Utility
Communication
Architecture
consists
of
definitions
of
generic

object
models
and
the
instructions
to
create
new
models.
The
UCA
protocol
is
divided
into

three
basic
building
blocks:
the
uniform
communication
infrastructure,
the
uniform
application

interface,
and
the
uniform
data
model.


The
UCA’s
first
building
block
is
the
Uniform
Communication
Infrastructure
which
contains
the

communication
layers.
Uniform
communication
Infrastructure
uses
UCA2
protocol
that
is

divided
into
three
layers
named
L
profiles,
T
profiles
and
A
profiles.
L
profile
layers
correspond

to
the
OSI
physical
and
data
link
layer.
The
L
profile
allows
LAN,
WAN,
or
asynchronous
serial

data
link
control
for
multi‐drop
links
for
SCADA
monitoring
and
control
systems.
L
profile

services
are
establishing
and
maintaining
channel
communication,
error
detection,
data

control,
connect,
disconnect,
send,
receive
and
status.
T
profile
layer
correspond
to
the
OSI

network
and
transport
layers.
T
profile
provides
end‐to‐end
delivery
of
whole
message.
T

profile
services
include
routing,
disassembly
and
reassembly
of
GOOSE
packets
and
GOOSE

message
error
detection.
UCA2
provides
two
options
at
T
profile,
one
is
using
the
ISO
network

and
transport
standards
for
LAN
and
WAN
protocols
and
the
second
one
is
using
the
IETF

network
and
transport
standards
for
multi‐drop
serial
data
link
infrastructure.
The
A
profile

layer
correspond
to
the
ISO
presentation,
session
and
application
layers.

A
profile
layer
is
the

most
robust
layer
because
it
is
responsible
for
generating
the
requested
data
by
using
the
lower

layers
to
achieve
end‐to‐end
transmission
of
the
GOOSE
messages
and
also
providing
services

at
the
application
layer
of
UCA2
compliant
Electronic
Intelligent
Devices.
A
profile
uses
two

applications
the
Abstract
Communication
Services
Interface
(ACSI)
and
the
Manufacturing

Message
Specification
(MMS).
Abstract
Communication
Services
Interface
(ACSI)
application

establishes
and
releases
communication
connections
between
application
functions
and


communication
functions.
The
Manufacturing
Message
Specification
(MMS)
application

provides
message
structure,
message
syntax,
and
message
dialog
procedures
for
monitoring

and
controlling
information
communication.


The
UCA’s
second
building
block
is
the
Uniform
Data
Model.
Uniform
data
model
contains

service
model
applications
such
as
event
model,
device
control
model,
data
access
control

model,
association
model,
security
model,
time
model,
multicast
services
model,
and
BLOB

model.
All
these
model
applications
exchange
information
between
them
by
using
the
Common

Application
Service
Model
(CASM)
that
provides
a
standard
set
of
communications
functions

and
other
data
handling
between
object
model
applications.


The
UCA’s
third
building
block
is
the
uniform
data
model.
Uniform
data
model
contains
logical

devices,
bricks,
components
data
classes
and
data
attributes
in
order
to
collect
the
specific

information
from
the
UCA
compliant
Electronic
Intelligent
Devices.
Uniform
data
model

standards
allow
the
extraction
of
data
from
the
UCA
compliant
Electronic
Intelligent
Device
to

obtain
the
required
information.


IEC
61850
(GOOSE)
Message
Structure






An
IEC
61850
GOOSE
message
is
created
by
the
Manufacturing
Messaging
Specification
(MMS)

protocol.
There
are
MMS
applications
for
Remote
Terminal
Unit
(RTU),
Energy
Management

System
(EMS),
and
other
Electronic
Intelligent
Device
(EID).
MMS
provides
a
set
of
services
for

peer‐to‐peer
real
time
real
time
communications
over
a
network.
MMS
standards
can
be

divided
into
two
parts.
MMS
part
1
is
the
service
specification.
Service
specification
includes

virtual
manufacturing
device
definition
(VMD),
the
services
or
messages
exchanged
between

nodes
on
a
network,
and
the
attributes
and
parameters
associated
with
the
VMD
and
services.

MMS
part
2
is
the
protocol
specification.
Protocol
specification
defines
the
rules
of

communication
including
the
sequence
of
messages
across
the
network,
the
format
or

encoding
of
the
messages
and
the
interaction
of
MMS
with
other
UCA
OSI
layers.
A
GOOSE

message
can
be
event‐driven
or
sent
once
every
minute.
Each
GOOSE
message
has
its
own
text

ID
name
and
special
multicast
Ethernet
destination
address.
GOOSE
message
has
one
special

characteristic:
the
Hold
Time
function
which
defines
how
long
to
consider
a
message
valid.







IEC
61850
(GOOSE)
Message
Transmission

In
IEC
61850
a
GOOSE
message
has
to
first
go
through
UCA
object
hierarchy
and
then
through

UCA
communication
protocol
layers.
Then,
when
UCA
compliant
electronic
intelligent
device

senses
that
one
status
or
event
changed
its
state
the
object
models
create
the
status
or
event

object
and
then
MMS
protocol
creates
a
GOOSE
message.
There
are
several
steps
to
creating
a

GOOSE
message.
First,
at
the
UCA
compliant
device,
the
status
or
event
is
converted
into
an

integer
value
which
is
called
data
attribute.
Second,
the
data
attribute
is
sent
into
a
component


data
class
which
is
a
collection
of
information
within
a
brick.
Third,
the
component
data
class

information
is
included
in
a
brick
(small
data
object).
Fourth,
the
brick
is
send
into
a
logical

device
that
provides
information
to
the
rest
of
the
logical
devices
using
Common
Application

services
Models
(CASM).
Fifth,
the
brick
is
sent
from
the
logical
device
to
the
Abstract

Communication
Services
Interface
(ACSI)
application
in
order
to
be
transferred
to
the
UCA

communication
profiles.
Sixth,
the
brick
is
transformed
into
a
GOOSE
message
by
the
MMS.

Seventh,
MMS
sends
the
GOOSE
message
to
the
lower
communication
layers
such
as
network,

transport,
data
link
and
physical
layers
(Profiles).
Now
a
GOOSE
message
has
been
created
and

ready
to
multicast
to
the
other
networked
UCA
compliant
devices.
In
this
situation,
the
UCA

compliant
device
broadcast
the
GOOSE
message
to
other
UCA
compliant
devices
which
decide

to
take
the
GOOSE
message
or
ignore
it.

IEC
61850
Security

IEC
62351
defines
security
for
IEC
61850.
IEC
62351‐3
defines
how
to
secure
TCP/IP‐based

protocols
for
real‐time
data
protocols.
IEC
6235‐4
defines
how
to
secure
Manufacturing

Message
Specification
(MMS)
based
protocols.
Security
objectives
include
authentication
of

data
transfer
through
digital
signatures,
and
intrusion
detection.






DNP3
Protocol

DNP3
is
a
communication
protocol
version
3.3.
DNP3
communication
is
defined
as

communication
between
master
stations,
remote
terminal
unit
(RTU)
and
any
other
Electronic

Intelligent
Device
(EID)
programmed
to
be
compatible
with
DNP3.
DNP3
allows
multiple

topologies
such
as
point‐to‐point
communication
(Master‐Slave),
multi‐drop
from
one
master,

and
multiple
masters.
DNP3
allows
EID’s
to
be
synchronized
with
a
master
unit
clock.
DNP3

data
can
be
encapsulated
to
be
transported
using
the
TCP/IP
protocol.


DNP3
Layers

DNP3
layered
architecture
is
conformed
to
the
International
Electrotechnical
Commission
(IEC)

Enhance
Performance
Architecture.
DNP3
uses
three
main
layers
such
as
application,
data
link,

and
physical,
but
add
some
pseudo
transport
and
network
functions.


Application
layer
is
the
highest
layer
in
charge
of
generating
the
requested
data
(Data
Object),

it
uses
the
lower
layers
to
achieve
end‐to‐end
transmission
of
the
DNP3
messages,
and
provides

services
to
user
application
programs
such
as
Human
Machine
Interface
(HMI),
Remote

Terminal
Unit
(RTU),
Energy
Management
System
(EMS)
and
other
Electronic
Intelligent

devices.
Data
link
layer
is
responsible
for
providing
reliability
in
the
communication
of
the

messages
or
frames
by
controlling
the
data
flow
and
detecting
data
errors.
Services
provided
by

the
data
link
are
establishing
and
maintaining
the
communication
channel,
report
channel


status
to
higher
layers
and
detect
and
correct
data
error
during
transmission.
The
physical
layer

is
the
physical
media
which
the
communication
protocol
uses
for
the
transmission
of
bits.
The

physical
media
has
separated
standards
for
the
transmission
of
data
such
as
ITU‐T
X.21,
DTE‐
DCE
V.24,
EIA
RS
232,
and
LAN.
The
services
provide
by
the
physical
media
are
connect,

disconnect,
send,
receive
and
status.


The
pseudo
transport
and
network
layers
are
responsible
for
providing
end‐to‐end
delivery
of

whole
messages
including
data
packets
disassembly
and
reassembly,
packet
routing,
packet

flow
control
and
packet
data
error
detection
over
networks.

DNP3
Message
Structure

DNP3
data
and
control
information
is
created
at
the
application
layer
into
data
objects.
The

collection
of
data
objects
is
called
a
library.
Each
data
object
has
a
structure
defined
by
DNP3

documentation.
There
are
90
data
objects
described
in
the
DNP3
Basic
Four
Documentation.

Object
group
0‐9
is
binary
input
object
that
represents
the
state
of
physical
input
or
a
software

input.
Object
group
10‐19
is
binary
output
object
that
represent
software
or
hardware
physical

outputs,
control
option
like
pulse
on,
pulse
off,
latch
on
and
latch
off.
Object
group
20‐29
is

counter
object
that
represents
accumulation
of
pulses
from
the
last
time
their
value
is

reported.
Object
group
30‐39
is
analog
input
that
represents
hardware
or
software
analog

input.
Object
group
40‐49
is
analog
output
that
represents
the
value
of
the
output.
Object

group
50‐59
is
time
object
that
represents
the
time
and
date
of
the
object.
Object
group
60‐69

is
a
class
object
that
represents
calling
or
requesting
for
objects
of
a
specific
class.
Object
group

70‐80
is
a
file
object
that
represents
a
file
identifier
data
object.
Object
group
80‐90
is
a
device

object
that
represents
device
data
flags.



DNP3
Message
Transmission

In
DNP3
each
layer
takes
the
data
object
and
adds
the
services
performed
by
that
layer
to
the

data
packet
and
then
sends
the
data
packet
into
the
lower
layers.
The
data
object
may
be
an

alarm,
event,
status,
or
control
signal
that
needs
to
be
send
from
the
master
to
IED
or
vice

versa.
The
application
layer
initially
converts
the
original
data
object
into
manageable
size

packets
called
application
service
data
units
(ASDU’s).
Then
application
layer
creates
an

application
protocol
data
unit
(APDU’s)
by
combining
the
application
layer
services
information

header
with
application
service
data
units.
Finally,
the
APDU
is
sent
to
the
transport
layer.
At

the
transport
data
layer,
the
APDU
changes
its
name
to
transport
service
data
units
(TSDU’s).
In

the
transport
layer
the
transport
service
data
unit
(TSDU)
is
spliced
into
smaller
units
called

transport
protocol
data
units
(TPDU).
Finally
the
TPDU
is
sent
to
the
data
link
layer.
At
the
data

link
layer,
the
TPDU
is
combined
with
a
data
link
header
and
finally
sent
to
the
physical
layer.
At

the
physical
layer
each
packet
is
converted
into
an
analog
representation
of
a
bit
stream
that
is


transmitted
utilizing
protocols
such
as
bit
serial
asynchronous,
8
data
bits,
start
and
stop
bits,

parity,
RS
232C
or
CCIT
V.24
(DTE‐DCE).


DNP3
Security

DNP3
was
never
designed
with
security
mechanisms
in
mind,
so
the
protocol
lacks
security.

One
way
to
use
security
in
DNP3
protocol
is
to
implement
DNP3
over
IP
and
add
IP
security

standards
such
as
IPsec.
Currently,
many
people
are
proposing
security
methods
for
DNP3

protocol

Comparing
DNP3
and
IEC
61850
protocols

1.
Overview
of
protocols

DNP3
is
a
protocol
that
defines
communication
between
master
stations,
remote
terminal
units

and
other
electronic
intelligent
devices.
DP3
is
an
open
protocol
that
makes
easier
third
party

applications
to
access
information
from
multiple
EID’s
from
multiple
vendors.
IEC
61850
is
an

open
communication
protocol
that
defines
communication
between
client/server
and
other

electronic
intelligent
devices.
The
main
key
in
IEC
61850
is
that
this
protocol
separates
the

application
functions
from
communication
functions.
IEC
61850
is
also
a
protocol
that
makes

easier
third
party
applications
to
access
information
from
multiple
EID’s
from
multiple
vendors.



2.
Polling
options

DNP3
has
two
ways
of
gathering
information.
The
first
type
is
polling,
master
request
all
events

(changes)
to
slaves.
The
second
type
is
unsolicited,
the
master
never
polls
and
relies
on

unsolicited
reports
only
from
the
slaves.
IEC
61850
is
unsolicited
(event‐driven),
electronic

intelligent
devices
send
information
only
when
an
event
changes
or
once
every
minute
to

maintain
up
to
date
new
devices
joining
the
network.

3.
Layered
architecture

DNP3
layered
architecture
is
conformed
through
the
International
Electrotechnical
Commission

(EIC).
DNP3
layers
are
physical,
data
link
and
application.
IEC
61850
layered
architecture
is

conformed
through
Utility
Communication
Architecture
(UCA).
IEC
61850
layer
L
profile,
T

profile
and
A
profile.


4.
Communication

DNP3
supports
peer‐to‐peer
communication
(master‐slave),
works
on
serial
communication
RS

232,
RS
485,
fiber
serial
loop
and
fiber
serial
start
configuration
and
also
operate
over
IP
and

networks
which
often
is
referred
as
DNP3
over
IP.
IEC
61850
support
peer‐to‐peer

communication
(EID‐EID)
and
operates
over
IP
and
networks.



5.
Features

DNP3
sends
and
receives
data
objects
often
named
points
such
as
status
information
about

devices
(binary
inputs),
analog
information
(analog
inputs),
accumulator
information
(counters),

set
points
(analog
outputs),
and
controls
(binary
outputs),
supports
time
synchronization
as

well
as
time
stamped
of
events
when
they
occur,
reports
static
data
(current
value)
and
event

data
(with
or
without
time
stamped).
IEC
61850
sends
and
receives
data
objects
often
called

bricks
with
status
and
event
information,
supports
process
bus
that
helps
to
minimize
wiring

requirements
to
equipment
by
converting
status
and
analog
information
into
bricks
at
the

source,
provides
a
highly
functional
object
oriented
solution
designed
to
support

implementation
and
maintenance
of
automation
applications,
supports
high
speed
peer‐to‐
peer
messaging
using
the
Generic
Object
Oriented
Substation
Event
(GOOSE)
and
Generic

Substation
Status
Event
(GSSE),
supports
many
different
protocols
because
maps
the
objects

and
abstract
communication
services
to
MMS
which
has
a
robust
set
of
features
that
maps
well

IEC
61850
objects
and
services.

Security

DNP3
protocol
lacks
security
standards.
IEC
61850
has
IEC
62351
protocol
that
provides
all
the

necessary
standards
for
encryption,
digital
signatures
and
intrusion
detection
for
IEC
61850

protocol.





Conclusion

Both
IEC
61850
and
DNP3
are
based
on
data
objects
concepts.
However,
IEC
61850
is
a
more

robust
communication
protocol
than
DNP3.
IEC
61850
contains
a
collection
of
multiple

protocols,
concepts
and
component
standards
that
make
IEC
61850
probably
more
than
a

communication
protocol.
On
the
other
side,
DNP3
is
a
simpler
standard
focused
on
three
layers

and
one
object
library.
However,
DP3
may
be
better
to
be
implemented
because
it
is

compatible
with
legacy
and
modern
SCADA
equipment.
In
general,
both
communication

protocols
have
different
way
of
communicating
the
data
IEC
61850
more
complex
than
DNP3,

but
they
both
do
the
same
real‐time
data
collection
function.


Personally,
when
I
started
this
class
I
did
not
know
a
lot
about
DNP3
or
IEC
61850.
After

completing
this
paper
not
only
am
I
able
to
understand
DNP3
and
IEC
61850,
I
am
also
able
to

understand
and
apply
how
a
real‐time
data
protocol
works.
That
alone
was
one
of
the
main

reasons
for
taking
this
class.
In
completing
this
assignment
there
were
two
main
challenges.

The
first
was
translating
complex
concepts
into
simple
terms.
My
second
challenge
was
to

condense
a
lot
of
information
into
in
five
page
document.





References

[1]
Clark
Gordon
and
Reynders
Deon,
Practical
Modern
SCADA
Protocols,
Newnes,
2004.

[2]
Stallings
William,
Data
and
Computer
Communications,”
Pearson,
9th
edition,
2011

[3]
Woodward
Darold,
“The
Hows
and
Whys
of
Ethernet
Networks
in
Substations,”
Schweitzer

Engineering
Laboratories,
Pullman,
WA,
USA.

[4]
“Overview
and
Introduction
to
the
Manufacturing
Messaging
Specification
(MMS),”
System







Integration
Specialist
Company,
Inc.,
1995.

[5]
“DNP3,”
Subnet
Solutions,
Inc.,
2012




























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