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SCADA OVERVIEW
• SCADA stands for ‘Supervisory Control and Data Acquisition’.
• SCADA is a software system used for monitoring, controlling and analyzing
industrial processes.
• The SCADA system communicates with the controllers( PLC or Remote
Terminal Unit-RTU) which are actually running the process.
• The controllers receive the signals from field devices and controls the process
according to the programs downloaded into them.
• SCADA systems communicates with the controllers in the field and collects
the actual field data. These data are then brought to the SCADA system and
shown through Graphical User Interface(GUI) to the operators in the field.
• The operators use these graphical representations to understand what is
happening in the process and provide the necessary control.
• SCADA software also provides options to enter settings through graphical
displays, allows the operators to view alarms, trends and other historical
Sdata.
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SCADA OVERVIEW
• SCADA products have been produced that are generic with a ‘one shoe fits
all’ approach to various markets i.e. one SCADA software is compatible with
various brands of PLCs
• These types of SCADA systems are used extensively throughout the Oil & Gas
market due to the fact that assets are spread over large geographical areas.
The other industries where the SCADA is used is the Water and Waste
Management system, Food and Beverage industries, power plants, etc.
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SCADA OVERVIEW
• In the overall structure of a SCADA system, there are four distinct levels
within SCADA, these being;
• Field instrumentation
• PLCs and / or RTUs
• Communications networks
• SCADA host software.
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SCADA OVERVIEW
Field Instrumentation
Instrumentation is a key component of a safe and optimized control system.
Traditionally, pumps and their corresponding operational values would have
been manually controlled i.e. an operator would start/stop pumps locally and
valves would have been opened/closed by hand.
Slowly over time, these instruments have been fitted with feedback sensors,
such as limit switches, providing connectivity for these wired devices into a
local PLC or RTU, to relay data to the SCADA host software.
PLC AND RTU
The PLC and the RTU are the actual devices that are connected to the field
devices. These devices receive data from the field devices and then transmit it
to the SCADA where the monitoring and control of field devices is done.
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SCADA OVERVIEW
REMOTE COMMUNICATIONS NETWORKS
The remote communication network is necessary to relay data from remote
RTU/PLCs, which are out in the field , to the SCADA host located at central
control center. With process distributed over a large geographical area,
communication is the important part of a SCADA system and essential for
operation.
SCADA HOST SOFTWARE
With development SCADA Host software platforms have many new features.
These included the development of integral databases specifically designed for
SCADA Host software requirements.
SCADA today are able to handle thousands of changes a second, for really large
systems, yet still conform to standard database interfacing such as Open
Database Connectivity (ODBC) and Object Linking and Embedding for
Databases (OLE DB).
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SCADA OVERVIEW
These standards are required so that third-party databases can access data
from the SCADA Host software.
Remote client access to the SCADA Host is another technology that has enabled
users to operate and monitor SCADA systems while on the move between or at
other locations.
SCADA Software Brands
Some of the SCADA soft wares used are,
• Wonderware Intouch
• GE-Intellution Fix
• GE-Cimplicity
• WinCC
• RS View32
