SCADA Systems: An Overview

Posted on May 12, 2024 in Computers

SCADA

Control via PC

The PC is being established in many fields (work, home, industry, etc.). Automated tasks that control and display were performed with PLC (programmable logic controllers or PLC) are being made with control systems based on PC using expansion cards or data acquisition.

Advantages:

  • Data processing, visualization, networking.

Disadvantages:

  • Real-Time, security, robustness.

As commonly used with PLCs, to the highest level, making monitoring and control tasks.

SCADA System

SCADA comes from the acronym for Supervisory Control And Data Acquisition.

  • It is an application of production control software that communicates with field devices and controls the process automatically from the computer screen.
  • Provides process information for various users: operators, supervisors, quality control, monitoring, maintenance, etc.
  • The user interface systems and ground-based control panels full of LEDs, measuring instruments, and buttons are being replaced by digital systems that implement the panel on a computer screen.
  • Direct control is performed by autonomous digital controllers and/or PLCs and are connected to a computer that performs the functions of dialogue with the operator, information processing, and production control using SCADA.
  • Basic Design of system acquisition, monitoring, and control.

Main Functions

  • Acquisition of data to collect, process, and store the information received.
  • Monitoring, from one monitor to observe the evolution of the control variables.
  • Control to modify the evolution of the process, acting either on basic self-regulators (slogans, alarms, menus, etc.). Well directly on the process through the outputs connected.

More Specific Functions

  • Transmission. Information with field devices and other PCs.
  • Database. Data management with low access times. Typically use ODBC.
  • Presentation. Graphical representation of data. Operator Interface or HMI (Human Machine Interface).
  • Exploitation. From the acquired data for quality management, statistical control, production management, and administrative and financial management.

Example of Operator Interface

Features

A SCADA package should offer the following benefits:

  • Ability to create alarm panels, which require the presence of the operator to recognize a stop or alarm condition, recorded incidents.
  • Generation of signal historical plant that can be turned over for trial on a spreadsheet.
  • Implement programs that modify the control law, or even the whole program on the robot, under certain conditions.
  • Possibility of digital programming, which allows high-resolution arithmetic on the computer CPU, and not on the PLC, less specialized, and so on.
  • Using macros, you can develop applications based on the PC, with data capture, signal analysis, screen displays, sending results to disk, printer, etc.
  • In addition, all these actions are carried out with a package of functions which includes areas of programming on a general-purpose language like C or Pascal, but now is catching on VBA (Visual Basic for Applications), which confers very high power and versatility.

Requirements

A SCADA must meet several objectives:

  • They must be open systems architecture that can grow and adapt according to changing business needs.
  • They must communicate with ease and transparently to the user with the plant equipment and the rest of the company (local and network management).
  • Should be simple to install programs without excessive hardware requirements, and easy to use, friendly user interface modules.

The Software Modules or Blocks Are:

  • Configuration.
  • Graphic Operator Interface.
  • Process Module.
  • Data File Management.
  • Communication.
  • Settings: Allows the user to define the working environment of your SCADA and adapted to the particular application you want to develop modules.
  • Operator Graphics Interface: Provides the operator control functions and monitoring of the plant. The process is represented by synoptic graphics.
  • Process Module: Executes preprogrammed control actions from the current values of variables read. Programming is done through program blocks in a high-level language (like C, Basic, etc.).
  • File Management and Data: Is responsible for the orderly storage and processing of data so that another application or device can access them.
  • Communications: Handles the transfer of information between the plant and the hardware architecture that supports the SCADA, and between it and the other elements for management.

Hardware Components

  • A SCADA consists of:
  • – Central Computer or MTU (master terminal unit).
  • – Remote computer or RTU’s (remote terminal units).
  • – Network communication.
  • – Field instrumentation.

Examples of SCADA Software

Some of the SCADA software, or include them as part of SCADA are:

  • AImax of Desin Instruments SA
  • CUBE, Orsi SA Spain
  • FIX from Intellution.
  • Lookout, National Instruments.
  • Monitor Pro, Schneider Electric.
  • SCADA InTouch, of LOGITEK.
  • SYSMAC SCS Omron.
  • Scatter Graph 5000 ABB.
  • – WinCC, Siemens.

Communication Interface

  • Allows the PC to access the field devices.
  • – Specific Drivers. Use the specific driver to fieldbus.
  • – Drivers OPC. Use a generic driver that each manufacturer provides OPC.

OPC Interface


• OPC (OLE for Process Control) interface with Microsoft is an automation components, providing easy access to data. The OPC Foundation is made up of Siemens, Fisher, Intuitive, OPTO 22, Intellution, Rockwell, etc..
• Applications that require services, ie data from the level of automation to process their tasks, as customers request them from the automation components, who both provide the required information as servers. The basic idea of OPC is to standardize the interface between OPC server and OPC client regardless of any particular manufacturer.
> • The services provided by OPC Servers OPC client interface through OPC typically involve reading, exchange and verification of process variables. Through these services can operate and control a process. OPC servers support the nexus of such applications any automation components that are networked via a fieldbus or Ethernet Industrial ..