2. SCADA SYSTEM
Supervisory Control And Data Acquisition
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.
3. SCADA SYSTEM
The Ability to Remotely collect data from 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.ant Messaging and SMS.
4. Scada Application
• 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
5. Scada Architecture
Supervisory Control And Data Acquisition
Central Monitoring Unit
Communications
Network
Sensor
Sensor
Sensor
Fiber, Radio, Modem,
Microwave, Telephone,
Wireless, Powerline Carrier
Remote
Terminal
Unit
(RTU)
RTU
RTU
7. Scada Hardware
Supervisory Control And Data Acquisition
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
9. RTUs differ from programmable logic controllers (PLCs) in that
RTUs are more suitable for wide geographical telemetry.
RTUs, PLCs and DCS are increasingly beginning to overlap in
responsibilities, and many vendors sell RTUs with PLC-like features
and vice versa.
In addition, some vendors now supply RTUs with comprehensive
functionality pre-defined, sometimes with PLC extensions and/or
interfaces for configuration.
Some suppliers of RTUs have created simple graphical user
interfaces GUI to enable customers to configure their RTUs easily. In
some applications data loggers are used in similar applications.
Comparison with PLC & DCS
10. Differences between SCADA and DCS,PLCs
SCADA DCS and PLC
geographically dispersed field sites. sub-systems are usually located
within a more confined factory or
plant-centric area
long-distance communication
systems
communications are usually
performed using local area network
(LAN) technologies
designed to handle long-distance
communication challenges such as
delays and data loss posed by the
various communication media used
usually employ greater degrees of
closed loop control than SCADA
systems
10
11. Remote Terminal Unit(RTU)
• An RTU monitors the field digital and analog parameters and
transmits data to the Central Monitoring Station. It contains setup
software to connect data input streams to data output streams,
define communication protocols, and troubleshoot installation
problems.
• An RTU may consist of one complex circuit card consisting of
various sections needed to do a custom fitted function or may
consist of many circuit cards including CPU or processing with
communications interface(s), and one or more of the following:
(AI) analog input, (DI) digital input, (DO/CO) digital or control
(relay) output, or (AO) analog output card(s).
• Small sized RTUs generally have less than 10 to 20 analog and
digital signals, medium sized RTUs have 100 digital and 30 to
40 analog inputs.
12. Remote Telemetry Unit(RTU)
• A microprocessor-controlled electronic device that
interfaces objects in the physical world to a distributed
control system or SCADA (supervisory control and data
acquisition) system by transmitting telemetry data to a
master system, and by using messages from the master
supervisory system to control connected objects.
• Another term that may be used for RTU is remote
telemetry unit, the common usage term varies with the
application area generally.
13. Single board RTU
• Single board RTU is compact, and contains all
I/O on a single board. The single board RTU
normally has fixed I/O (eg.16 digital inputs, 8
digital outputs, 8 analogue inputs, and say 4
analogue outputs).
14. Modular RTU
• Modular RTU has a separate CPU module, and
can have other modules added, normally by
plugging into a common "backplane" (a bit like a
PC motherboard and plug in peripheral cards) is
designed to be expanded by adding additional
modules.
16. Master Station
The central site/master station can be pictured as having one or more
operator stations connected to a communication system consisting of
modem and radio receiver/transmitter.
The features that should be available are:
Operator interface to display status of the RTUs and enable operator
control
Logging of the data from the RTUs
Alarming of data from the RTU
Master station has two main functions:
Obtain field data periodically from RTUs and submaster stations
Control remote devices through the operator station
17. Intelligent Electronic Devices (IED)
An IED is a “smart” sensor/actuator containing the
intelligence required to acquire data, communicate to other
devices, and perform local processing and control. An IED
could combine an analog input sensor, analog output, low-
level control capabilities, a communication system, and
program memory in one device. The use of IEDs in SCADA
and DCS systems allows for automatic control at the local
level.
18. Human-Machine Interface (HMI)
The HMI is software and hardware that allows human operators
to monitor the state of a process under control, modify control
settings to change the control objective, and manually override
automatic control operations in the event of an emergency. The
HMI also allows a control engineer or operator to configure set
points or control algorithms and parameters in the controller.
The HMI also displays process status information, historical
information, reports, and other information to operators,
administrators, managers, business partners, and other
authorized users. The location, platform, and interface may vary
a great deal. For example, an HMI could be a dedicated platform
in the control center, a laptop on a wireless LAN, or a browser on
any system connected to the Internet.
19. Communication
Wireless Data Transmission (serial and/or IP)
VHF (150 MHz), requires FCC license
UHF (450 MHz), requires FCC license
900+ MHz, spread spectrum
Cellular
Satellite
Wired Data Transmission
Phone
leased line or PSTN (dialup)
Private Line Network
Internet
20. Communications Routers
A router is a communications device that transfers
messages between two networks. Common uses for
routers include connecting a LAN to a WAN, and
connecting MTUs and RTUs to a long-distance network
medium for SCADA communication.
21. SCADA Communication Topologies
MTU-RTU communication architectures vary among implementations.
The various architectures used, including point-to-point, series, series-
star, and multi-drop.
Point-to-point is functionally the simplest type; however, it is
expensive because of the individual channels needed for each
connection.
In a series configuration, the number of channels used is reduced;
however, channel sharing has an impact on the efficiency and
complexity of SCADA operations.
Similarly, the series-star and multi-drop configurations’ use of one
channel per device results in decreased efficiency and increased system
complexity.
The four basic architectures shown in Figure 2-3 can be further
augmented using dedicated communication devices to manage
communication exchange as well as message switching and buffering.
