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What is SCADA?


  • The SCADA concept was developed to be a universal means of remote monitoring of the control system.
  • The primary function of SCADA is Monitoring.
  • Supervisory- To Monitor the process happening in the field.


  • Secondary function of SCADA is controlling.
  • Control the process variables in the field when it requires.


  • if the sensors in the field is not working, we can operate the plant by using SCADA System.
  • It is also called as Industrial Computer Control System.

Data Acquisition:

  • To gather the data in real time.
  • Data means Process variables like Temperature, Pressure, Level, Flow, Speed, etc.
  • Record System events into a log file.
  • Information Storage and Reports


Introduction to SCADA

SCADA is an acronym that stands for Supervisory Control and Data Acquisition. SCADA refers to a system that collects data from various sensors at a factory, plant or in other remote locations and then sends this data to a central computer which then manages and controls the data.


A collection of equipment that will provide an operator at a remote location with enough information to determine the status of a particular piece of equipment or entire substation and cause actions to take place regarding the equipment or network.

SCADA System Concept:

  • SCADA refers to the centralized systems that control and monitor the entire sites, or they are the complex systems spread out over large areas.
  • Nearly all the control actions are automatically performed by the remote terminal units (RTUs) or by the programmable logic controllers (PLCs).

Basic Components of SCADA System:

A basic SCADA system consists of the following components:

  • Human Machine Interface
  • Supervisory System
  • Remote Terminal Units
  • Programmable Logic Controllers (PLCs)
  • Communication Infrastructure
  • SCADA Programming

SCADA Software:

SCADA Software is a set of Programs and modules that provides the features of the SCADA System.

  1. SCADA Server
  2. Operator Interface
  3. Drivers
  4. Data Interfaces

SCADA Server:

The SCADA Server is a service (or, daemon) that runs in the background. The SCADA Server:

  • Runs drivers to interface with each PLC or Data Source.
  • Manages the SCADA Database. The SCADA Database contains:
    • Tag Configuration and Data
    • Graphic Pages
    • The list of Alarms (Abnormal Conditions)
    • Historic Data for Trends
    • Events data for the events log
  • Accepts connections from and provides data to:
    • The operator interface
    • Configuration Tools
    • Data Interfaces

Operator Interface:

The Operator Interface connects to the SCADA Server to provide the information operators need.


  1. Graphics Pages
  2. Trends
  3. Alarms
  4. Event Log

Multiple operator Interfaces can connect to the same SCADA Server. This allows many operators to jointly manage the same Automation Process.


A Driver is an interface between the SCADA Server and an external device. Different drivers are created for each protocol or, device family. Common Drivers found in SCADA systems include:

  • Modbus
  • OPC Client
  • DNP3
  • Mitsubishi PLC
  • Siemens PLC
  • Allen Bradley PLC
  • Omron PLC
  • SNMP, etc.

Data Interfaces:

Some SCADA Applications require an interface to other systems. For example MES Or, ERP.
A SCADA System should provide Data Access interfaces to make this possible.


Window is the base or, Plateform where we can Design or Develop the Project.

Window Types:

  • Replace: Automatically Closes any window(s) it intersects when it appears on the screen including popup other Replace type windows.
  • Overlay: Appears on the top of the currently displayed window(s) and can be larger than the windows it is overlaying. when an overlay window is closed, any window(s) that were hidden behind it will reappear.
  • Popup: Similar to an overlay window except, it always stays on top of all other open windows.

Tag Name/Points:

Memory or Input / Output variables are called Tag Name / Points.
When we are defining tag names in the Intouch database, we must assign a specific type to each tag name according to its uses.

Memory Type Tag Name:

Memory type Tag Names exit internally within our Application. You use them to create system constants and Simulations.

Memory Discrete: 0 or, 1
Memory Integer: Signed Integer Value b/w -2147483648 & 2147483647.
Memory Real: Floating (decimal) Point memory Tag name Value b/w -3.4e38 and 3.4e38
Memory Message: Text String Tag Name that can be upto 131 characters long.

I/O Type Tag Name:

All Tag Names that can read or, write their values to or, from another windows Program are I/O Type Tag names.

I/O Discrete: 0 or, 1
I/O Integer: Signed Integer Value b/w -2147483648 & 2147483647.
I/O Real: Floating (decimal) Point Tag name. It is used to communicate decimal point values between controllers and SCADA.
I/O Message: Text String Input.Output Tag Name that can be upto 131 characters long.

Miscellaneous Tag Types:

There are Several Tag types that you can assign to tags that perform complex functions, such as creating dynamic alarm displays, historical trends, monitoring or, controlling the tag that each historical trend Pen is plotting, and so on.

Group Var: The group Var type is used for a Tag with an assigned Alarm group to create dynamic alarm displays disk logs and Print Logs.
Hist Trend: Intouch requires a Hist Trend type tag when you create a historical trend.
Tag ID: This is a special type that is used with historical trend objects.

Indirect Tag:

Indirect type tags allow you to create one window and reassign the tags in that window to multiple sources.

For Example, You could create a data change quick script that would modify the source for all tags in a window, based on a value that has changed.

When you equate an indirect tag to another source tag, both the indirect and the source tags become exact duplicates of each other in every aspect including fields, Scripts and so on.

Licensing Patterns Used In SCADA Software

Typically two types of licenses are used in the SCADA Software.

  • Dongle Key: It is a hardware lock that can be put on the communication port of the PC.
  • Software Lock: Here the software code is the license. Typically you can put the code while installation or transfer the code from floppy to hard disk.

Wonderware SCADA Packages:

  1. No. of I/Os: Wonderware Intouch comes in 64, 128, 256, 1000, and 64000 tags packages.
  2. Development + Runtime + Network (DRN)/ Runtime + Network (R+N) and View Node:
    • D + R + N: With this package development and editing of the application is possible, Runtime monitoring and control of the plant is possible and Networking is Possible. (For Manufacturer Company)
    • R + N: With this package development and editing of the application is not possible, Runtime monitoring and control of the plant is possible and Networking is possible. (For Industrial Use)
    • Factory Focus: With this Package development and editing of the application is not possible, Runtime monitoring is possible but control of the plant is not possible and Networking is possible. This package is used a View Node. (For Monitoring only)

Features Of SCADA:

  1. Dynamic Process Mimic or, Animation Control
  2. Alarms and Events
  3. Trends
  4. Security
  5. Recipe Management
  6. Scripts
  7. PLC SCADA Interfacing
  8. Data Connectivity

1. Dynamic Process Mimic or, Animation Control:

Colour Fill, Percent Fill, Size Control, Location, Orientation, Visibility, Action, Hide/Show Window etc.

2. Alarms and Events:

Alarms and Events are the notifications used to inform operators of process activity: Alarms represent warnings of process conditions that could cause problems, and require an operator response.

A typical Alarm is triggered when a process value exceeds a user-defined limit.

Intouch uses two different types of Alarms:

  1. Discrete Alarm
  2. Analog Alarm

Events represent normal system status messages and do not require an operator response.

A typical event is triggered when a certain system condition takes place, such as an operator logging into in touch.

3. Trends:

Trends Mean graphical representation of Data.

  • Real-Time Trends
  • Historical Trends

We can configure both Trend objects to display graphical representations of multiple Tag Names over time.

Real-Time Trends allow you to chart up to four pens (data values), while Historical trends allow you to chart up to eight pens.

Real-Time trends are dynamic. They are updated continuously during runtime with whatever time span is given in the configuration. You cannot scroll the real-time trends to see previous data.

Historical trends provide us with a ‘Snapshot’ of data from a time and date in the past They are not dynamic. Unlike real-time trends, historical trends are only updated when they are instructed to do so either through the execution of a Quick script or, an action by the operator. For Example, By Clicking a button, you can Zoom In/ Zoom Out the trends. You Can also excess the previous data.

4. Security:

Security Provides the ability to control whether or, not specific operators are allowed to perform specific functions within an application.

Security is based on the concept of the operator ‘Logging On’ to the application and entering a ‘Use Name’ and ‘Password’. (The Application developer sets up each operator with a ‘User Name’, a Pre-assigned ‘Password’ and an “Access Level” via the ‘Special/Security/Configure Users.’ Command either in Window Maker or Window Viewer).

When a New application is created, the default “User Name” is “Administrator”, and “Password” is “Wonderware” with an Access level of 9999 (Which allows access to all security Commands).

5. Recipe Management:

Recipe in the SCADA Systems are used to configure the machine or, Production Process to perform the fixed tasks as per the application.

  • Template Definition
  • Unit Definition
  • Recipe Definition

6. Scripts:

Script is a way of writing logic in Intouch. Intouch has its own instructions and way of writing Programs.

  1. Application Script: Linked to the entire Application.
  2. Window Script: Linked to a specific window.
  3. Key Script: Linked to a specific Key or, Key Combination on the keyboard.
  4. Condition Script: Linked to a discrete Tag name or expression.
  5. Data Change Script: Linked to a tag name and/or tag name field only.
  6. Quick Function Script: Linked to one or, more Quick Functions.

7. PLC SCADA Interfacing:

8. Data Connectivity:

In this feature, We will learn Interfacing with Ms-Excel.

DDE (Dynamic Data Exchange):

Dynamic Data Exchange is the facility developed by Microsoft for exchanging data between various Programs. DDE has three important Settings:

  • Application / Server Name
  • Topic Name
  • Item Name

Some SCADA Companies and Their Linking Driver/Driver:

Linking Driver or Driver is software that allows SCADA to access the external device.

OPC (Open Plateform Communication):

OPC stands for Open Platform Communications or some say OLE (Object Linking and Embedding) for Process Control. It is a type of protocol used in Industrial Automation.

The OPC is always used in the Client/Server pair. The OPC server converts the hardware-communicated data from PLC into OPC protocol. So that other software
like SCADA can access the data.

The OPC server is a program that often connects with hardware like HMI to get the data and convert it into OPC protocol.

The OPC client communicates with the OPC server to receive data or send commands to the hardware.