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SCADA ProtocolsSCADA Protocols

Overview of DNP3

By Michael LeMay

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IntroductionIntroduction

DNP3 used for communications betweenSCADA masters (control centres) and remote

terminal units (RTUs) and/or intelligent

electronic deices (!"Ds)

DNP# Distributed Networ$ Protocol

SCADA# Su%erisor& Control And Data Ac'uisition

Protocol defined in asic *+ document set fromDNP Users ,rou%

ased on !"C -.0.12

!nternational counter%art# !"C -.0.1214.4

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Protocol OverviewProtocol Overview

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Protocol ParticipantsProtocol Participants

SCADA 5aster Stations/Control centres

Connected to 65! and ot7er control centres

Remote terminal units !nterface between !"Ds and master stations

5a& e87ibit limited autonomous control

!ntelligent electronic deices Sensors and meters

Rela&s and ot7er actuators

Programmable 9ogic Controllers# P9Cs

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SCADA Master BasicsSCADA Master Basics

Control centre from w7ic7 multi%le substationsor ot7er remote installations are controlled andmonitored

Connected to ot7er control centres using !CCP:

a se%arate %rotocol

!nterfaces wit7 7uman t7roug7 65! (6uman15ac7ine !nterface): w7ic7 ma& be local or

remote Connected to RTUs and/or !"Ds

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Saple SCADA MastersSaple SCADA Masters

;orean control center

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!"# Basics!"# Basics

Remote Terminal Unit A%%ears as !"D to SCADA master w7en DNP

used for communications

5anages multi%le actual !"Ds Attac7ed !"Ds referenced using absolute

addressing sc7eme

Addresses onl& 7ae meaning to SCADAmaster

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Saple !"#sSaple !"#s

CellularRTURadioRTU

Serial RTU

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I$D BasicsI$D Basics

!ntelligent "lectronic Deice

5a& be data ac'uisition deice onl&

5a& be res%onsible for control

Possible in%uts# configuration: setting: and

command data

Possible out%uts# alues: conditions: status: and

results

5a& be P9Cs %rogrammed wit7 ladder logic

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Saple I$Ds%PLCsSaple I$Ds%PLCs

Programmable 9ogic Controller (P9C)

!ntelligent"lectronic

Deice

(!"D)

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ParaetersParaeters

!"Ds and RTUs can control and monitor aariet& of %7&sical %rocesses and ot7erinformation#

Accumulate measurements li$e $ilowatt 7ourconsum%tion

5onitor oltage and current

5onitor tem%eratures (useful for automaticall& controllingtunnel fires)

Switc7 electrical brea$ers on and off

Transfer configuration files to/from SCADA master

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DNP3 Protocol StandardDNP3 Protocol Standard

T7e DNP3 %rotocol standard defines seeral as%ects of SCADA5aster1RTU/!"D communications#

=rame and message formats

P7&sical la&er re'uirements

4>.. b%s? us& lin$ indicator for collision aoidance

Data1lin$ la&er be7aior

frame segmentation

Transmission retr& algorit7m A%%lication la&er

file transfer time s&nc7roni@ation

start/sto% serice

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Protocol BasicsProtocol Basics

uilt on S! la&ers 4:>:0

A%%lication

Presentation

Session

Trans%ort

Networ$

Data 9in$

P7&sical

!"C "n7anced Performance Arc7itecture+

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Basic Messa&e Brea'downBasic Messa&e Brea'down

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Protocol !e(uireentsProtocol !e(uireents

Com%onents o%erate in 7ars7 enironments

Protocol designed for reliabilit&

No confidentialit& or integrit& c7ec$s e8%licitl&included

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!e()* +Data Security,!e()* +Data Security,

Correct data transmission re'uired in %resence

of#

"5!# "lectromagnetic interference

Differences in eart7 %otential

Aging com%onents

t7er sources of noise and disturbance along

transmission %at7

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!e()* Data Security -cont).!e()* Data Security -cont).

Protection e8%licitl& afforded against#

Undetected bit errors

Undetected frame errors caused b& s&nc7roni@ation

errors

Undetected loss of information

,ain of unintended information

Simulation of alid message b& noise

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/or More Info)))/or More Info)))

DNP was originall& deelo%ed b& ,"16arrisCanada in 4BB. and released in 4BB3

Now managed b& t7e DNP Users ,rou%#

7tt%#//wwwdn%org

T7e DNP Users ,rou% includes master station:

RTU and !"D endors: and re%resentaties of

t7e electric utilit& and s&stem consulting

communities !""" Std 430B1>... %roides modern

im%lementation best %ractices

5& SCADA 9in$s# 7tt%#//tin&urlcom/d't>8

http://www.dnp.org/http://tinyurl.com/dqt2xhttp://tinyurl.com/dqt2xhttp://www.dnp.org/