scada 121808 final

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Secure Systems Research Group- FAU 1

SCADA Software Architecture

Meha GargDept. of Computer Science and Engineering

Florida Atlantic University

Boca Raton, FL, USADecember 18, 2008.

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Agenda

Motivation

Objective

Introduction

SCADA

Use Cases and Application ofPatterns

Questions

Recommendations

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Motivation

Critical Infrastructure systems like Supervisory, Controland Data Acquisition Systems (SCADA), Distributed

Control System (DCS), used in Energy Industry and

Process Industries are highly distributed and complex.

It would be interesting to study SCADA using Use Casediagrams and applying various patterns Layers, Model

View Controller, Web Services, Broker, etc., applying our

secure software methodology

This kind of work will help understanding of SCADAsystems and Cyber Physical Systems, apply Non

Functional Requirements, and do model checking.

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Objective

To discuss Use Case Diagram for SCADA, then

define a software architecture using patterns

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Introduction

SCADA (Supervisory Control and Data Acquisition) systems are used to monitor andcontrol a plant or equipment in industries such as telecommunications, water and wastecontrol, energy, oil and gas refining, and Transportation (airport, traffic control, rails)

These systems encompass the transfer of data between a SCADA central hostcomputer and a number of Remote Terminal Units (RTUs) and/or Programmable LogicControllers (PLCs), and the central host and the operator terminals

A SCADA system gathers information (such as where a leak on a pipeline hasoccurred), transfers the information back to a central site, then alerts the home stationthat a leak has occurred, carrying out necessary analysis and control, such asdetermining if the leak is critical, and displaying the information in a logical andorganized fashion

These systems can be relatively simple, such as monitoring environmental conditionsof a small office building, or very complex, such as a system that monitors all theactivity in a nuclear power plant or the activity of a municipal water system

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Use Case Diagram for SCADA System

Description: The goal is to supervise, control, monitor andacquire data for critical infrastructure systems, operate from

remote end and ensure security and safety

Actors:

Field Devices Local Control Center (LCC)

Remote Telemetry Units (RTU)

Master / Central Control Terminal Unit (MTU)

Operator

Supervisor

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Use Cases

1. System Shut Down / Startup2. Gather Field Information

3. Perform Local Control

4. Transfer Field Information

5. Manage Field Information

6. Perform Remote Control7. Analyze System State

8. Schedule Task

9. Balance Load

10. Adjust Settings11. Check Status

12. Manage Logging

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SCADA System

Check

Status

Field Devices

Local Control Center

Remote Terminal Unit

Transfer

Information

Perform

Local

Control

Manage

Field

Information

Analyze

System

StateSchedule

Task

Balance

Load

Central Control Terminal Unit

System

Startup/

Shutdown

Operator

Gather Field

Information

Manage

Logging

AdjustSettings

Perform

Remote

Control

Supervisor

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Pre Conditions for SCADA

System1. The operator is logged in.2. The system is real time system.

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Layers

Hardware

Layer

Distribution

Layer

Communication

System

System Level

Application

Layer

Field

Devices

Actuators SensorsField Device

Units

RTU IED Bay Control

Units

ModBus IEC 61850 DNP 3 Ethernet: TCP/IP Protocols

HMIPrinters GPS RoutersSwitches

Data

Gathering

Transport

Layer

System

Startup/Shutdown

Check Status Adjust Settings Perform Control

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Layer Pattern SCADA system being highly complex and distributed, it is important to

understand SCADA in Terms of Layers for simplicity as shown in Figureabove. The intent, forces, advantages for the layer Patterns are the

same. However here we apply this pattern on the real physical system.

Layer 1: It is the field Units, considering the Generation, Transmission

and Distribution at one place, we have all the process controls, I/Os,

status, metering, measuring values, etc. It also includes local control.

Layer 2: The field values, I/O analog, digital, measuring and other

commands, operations, are taken to RTUs, IEDs, PLCs, BCUs, and

other I/O cards to communicate to higher end.

Layer 3: This includes all the communication cables, protocol

architecture required for higher end communication interfaced with allfield signals. It is the backbone in the modern control centers, which has

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Layer Patternimmensely reduced physical wiring, big marshalling and increased the

reliability and more improved quality signals. Today latest protocols likeIEC 61850, Modbus and other proprietary protocols are used.

Layer 4: This includes the Control centre equipped with dynamic

changing states of the system displayed on HMI, which is powerful to

read values, prompt and diagnosis system change and with a click on

HMI, to carry out operations.

Layer 5: Connection with the outside world using Internet and various

new technology related to mobile / cell phone operations.

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Secure Systems Research Group- FAU

More Patterns

We can app ly more patterns :

Broker (Inter substation control)

Client Sever Dispatch (Between Main

system and operator console) Web Services (Internet Control)

Model View Contro l ler (HMI)

Three-tier

Unif ied Phys ical Access Contro l to

Bu i ld ings and inform at ion

13

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Future Work

Safety Monitor Implementation in SCADA System

Unifying Safety with Security

Implementing more patterns in SCADA

Formalization of safety

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Recommendations and Questions

Feedback:

scada 121808 final

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