This document provides an overview of supervisory control and data acquisition (SCADA) systems. It defines SCADA as a combination of telemetry and data acquisition used to remotely monitor and control industrial equipment and processes. The document outlines the basic components of a SCADA system including field devices, remote terminal units, a master terminal unit, and communication networks. It also discusses where SCADA systems are commonly used, new trends like web-based interfaces and mobile access, and security considerations for SCADA.

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Ramtin Raji Kermani
Fall 2005
Computer Sciences & Engineering Department
Shiraz University

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Road Map:
• What is a Control System?
• What is SCADA ?
• Where and why SCADA is used?
• SCADA architecture
• Components of SCADA
• Security issues
• Modern features

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First of all, Lets see what is a Control System ?
A control system, is a system that holds responsible in top of another system
(being controlled system) for setting and stabling the system in a predefined
state.
Nowadays control systems are mostly microprocessor based. (Microcontrollers,
PLCs, PC-Based Control systems).
Process being controlledSensor Actuator
Controller System

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Example of a monitoring and control system is a system which
monitors temperature and switches heaters on and off.

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What is SCADA?
SCADA is “Supervisory Control And Data Acquisition”.
Real-time industrial process control systems used to centrally
monitor and control remote or local industrial equipment such as
motors, valves, pumps, relays, sensors, etc.
SCADA is Combination of telemetry and Data Acquisition.
SCADA is not just a hardware, neither a software. It’s a concept,
it’s a system as a combination of special hardware, software and
protocols.
SCADA is used to control chemical plant processes, oil and gas
pipelines, electrical generation and transmission equipment,
manufacturing facilities, water purification and
distribution infrastructure, etc.

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Why SCADA is needed ?
The Ability to Remotely collect different plants on different places.
The Ability to control process from a distance.
The Ability to create logs and reports about system’s current and past state.
The Ability to send necessary information to Engineers and operators in
real-time using Instant Messaging and SMS.

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Where SCADA is used ?
- Electrical generation/distribution,
- Natural gas distribution
- Fuel Oil storage & flow
- Water storage & flow
- Lighting
- Heating, cooling, ventilation
- Fire alarms & suppression
- Elevators & escalators
- Gates & doors, alarms
- Video security cameras
- Traffic signals
- Process Line Control

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SCADA is not a new stuff !
It has been used since the early days of control systems to
remotely Control and Monitor current and past state of being
controlled system (our plant, factory, etc.)

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Early Power System Control (in 1919)
Control room
(mimic wall)
1970’s
formerly, all instruments were directly wired to the control room

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Late 1990’s Control Centers

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A little Confused ?!?!
Lets SEE what it is !

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Central Monitoring Unit
Communications
Network
Sensor
Sensor
Programmable Logic Controller
Sensor
Fiber, Radio, Modem,
Microwave, Telephone,
Wireless, Powerline Carrier
Remote
Terminal
Unit (RTU)
RTU
RTU

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SCADA Hardware
- Field level instrumentation and control devices
Sensing field variables, controlling the process and ….
- Remote Terminal Units (RTUs)
Send control and monitoring data to MTU. (could be a PLC)
- Master Terminal Unit or MTU (Also called The Master Station)
gathering information from RTUs, Monitoring and processing,
sending necessary control actions to RTUs.
- Communication System

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Going a little more in details …

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Communication
Network
Instrumentation
Remote Station
Central Monitoring Station
LAN, WAN, INTERNET
Communication
Network
Instrumentation
Remote Station
Central Monitoring Station
Central Monitoring Station
Communication
Network
Instrumentation
Remote Station
Corporate Architecture

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•Focus
–Safety
–100% Availability
–Electro-mechanical
–No updating, Aged
equipment
•The Language
–RTUs, PLCs, IEDs
– DNP, Modbus
– Low Bandwidth
– Analog & Digital
•The Vendors
–Allen
Bradley(AB)/Rockwell,
Honeywell, Siemens,
Johnson Controls
•Focus
–Security
–99.5% Availability
–Electronic
–Continuous Updating,
New
•The Language
–Routers, Switches,
Servers
– IP, Ethernet
– High Bandwidth
– All Digital
•The Vendors
–IBM, Microsoft,
CISCO, Dell
Physical Plant Computer Networking
What are the concerns ?

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Protocols used in SCADA Systems:
DNP (Distributed Network Protocol)
Modbus
DeviceNet
Mostly Open Protocol are used in SCADA systems.
The most popular protocols are as follows:

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SCADA Functionality:
- Data acquisition and display
store binary & analog data into process data base
- Alarm & Events
record important changes and operator actions
- History data base
keep a record of the process values
- Measured processing
calculate derived values (limit supervision, trending)
- Logging & reporting
- Human Machine Interface (HMI):
graphical object state presentation, lists, reports
- Operator Command handling
binary commands, set points
recipes, batches, scripts (command procedures)

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Current state
Alarms and events
Trends and history
Remote Monitoring including:

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What is an alarm, an event ?
A&E consider changes occurring in the plant (process) or in the control system
(operator actions, configuration changes,…) that merit to be recorded.
Recorded changes can be of three kinds:
- informative: no action required
(e.g. "production terminated at 11:09")
- warning: plant could stop or be damaged if no corrective action is taken "soon"
(e.g. “fuel low")
- blocking: the controller took action to protect the plant and further operation is
prevented until the reason is cleared (e.g. “Temperature too high")
An event is a change related to:
operator actions ("grid synchronisation performed at 14:35"),
configuration changes ("new software loaded in controller 21"), and
system errors ("no life sign from controller B3")

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Implementing alarms by variables
An alarm is often encoded as a simple 16-bit word sent by an object (thru PLC) in the
plant.
Each bit has a different meaning, the error condition is reset when the word is 0.
[120] low oil pressure
121] low water level
[122] trajectory error
[123] synchronisation error
[123] tool error
[131] robot %R1% not ready
…
word

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New Trends in SCADA
- Web-Based SCADA systems
- Connecting SCADA system to Internet
- Gives more functionality to our system
- Security issues should be covered
- Using Instant Messaging to report systems status (implemented)
- Giving more functionality
- Using a reliable instant messaging service
- Using Short Message Service to report critical situations (implemented)
- A kind of instant messaging, using Mobile Telecommunication network
- Using SMS Server, connecting a cell to PC, setting up a web server and
using WAP

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Instant Messaging for SCADA
Facilitate the remote monitor and control by utilizing the secure IM
Instant Messaging (IM) is a type of communications service over the Internet that
enables individuals to exchange text messages and track availability of a list of
users in real-time.
By taking advantage of the near real time feature of IM and richness of the IM
presence, we bring forward a secure IM based remote monitor and control
system.
LDAP-based device and system management
Lightweight Directory Access Protocol (LDAP) [6] specifically targeted at
management applications and browser applications that provide read/write
interactive access to directories.

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Internet
PDA
Cell Phone
`
Computer
IM server
LDAP Server
`
IM Control/Mornitor
Proxy
Device 3
`
node1
Device 1
Device 2
Device 4
`
node2
`
Leader node1
firewall
Group key
IM Architecture for SCADA

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A simple IM based remote monitor/control interface

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SCADA on mobile phone
The system allows you to use your mobile phone to monitor and control your
process from any location. More versatile than a pager system.
You can get detailed alarm messages about any event that occurs in your
business.
The application has been
written in J2ME
The refresh time is about 2 s
Java application in mobile
phone transfers data to/from
WWW server.

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Last words on SCADA
With new trends and technologies of Computer and Electrical
Engineering, there are lots of functionalities available, that we can add to our
SCADA system.
You saw that SCADA covers different fields of Computer Engineering like
Computer networking, Control, Programming, Embedded Systems, Operating
Systems, Real-time Systems and ….
SCADA is a very fast growing technology which is widely used in plants and
factories and makes good job opportunities for you in the industry, in
computer engineering field..

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References:
www.google.com
www.wikipedia.com
www.whatis.com
Modern SCADA protocols, Elsevier, newness publication
DESY SCADA Experience, EPICS Workshop - Oak Ridge
www.modbus.com
www.DNP.org
Engineering The Architecture Of Distributed Control Systems, Eric Runnerstrom
MPR Associates
Joint Program Office for Special Technology Countermeasures, National Defense
Industrial Association
15-17 July 2003

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Questions ?
Comments?
Thanks for coming …
Ramtin Raji Kermani, Fall 2005
ramtinraji@cse.shirazu.ac.ir