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SCADASupervisory Control and Data AcquisitionSCADA refers to the combination of telemetry and data acquisition.SCADA encompasses collecting of the informationtransferring it back to the central sitecarrying out any necessary analysis and controldisplaying that information on a number of operator screens or displaysThe required control actions are then conveyed back to the processFundamental principles of modern SCADA systemsSCADA hardwareRTU Remote Terminal UnitThe RTU provides an interface to the field analog and digital sensors situated at each remote site.Master StationThe master station (or sub-masters) gather data from the various RTUs and generally provide an operator interface for display of information and control of the remote sites.SCADA hardwareCommunication SystemThe communications system provides the pathway for communication between the master station and the remote sites. This communication system can be wire, fiber optic, radio, telephone line, microwave and possibly even satellite. Mainframe Computer or CPU with Operator DisplaysThe Mainframe Computer or CPU get Data from the Master stations, process, store, simulate and display in various trends on operator Displays. It sends back supervisory actions to the field actuators on the basis of data.

SCADA HardwareSCADA SoftwareTwo Types of SCADA Software:

Proprietary Software Package : Companies develop proprietary software to communicate to their hardware. These systems are sold as turn key solutions. The main problem with this system is the overwhelming reliance on the supplier of the system.

2.Open Software Package : Open software systems have gained popularity because of the interoperability they bring to the system. Interoperability is the ability to mix different manufacturers equipment on the same system. Citect from Schneider and Wonderware are two popular SCADA Open Software Packages.

SCADA Software SystemSCADA Software SystemKey features of SCADA software are: User interface Graphics displays Alarms Trends RTU (and PLC) interface Access to data Database Networking Fault tolerance and redundancy Client/server distributed processingSCADA Software System

User Interface and Graphic Display

SCADA Software SystemUser Interface and Graphic DisplaySCADA Software SystemUser Interface and Graphic Display

Plant Display on Internet Browser supporting Application Programming Interface (API) SCADA Software System

SCADA Software SystemAlarms Page SCADA Software SystemTrends Page

Considerations of SCADA systemTypical considerations when putting a SCADA system together are: Overall control requirements Sequence logic Analog loop control Ratio and number of analog to digital points Speed of control and data acquisition Master/operator control stations Type of displays required Historical archiving requirements System consideration Reliability/availability Speed of communications/update time/system scan rates System redundancy Expansion capability Application software and modelingImproved operation of the plant or process resulting in savings due tooptimization of the systemIncreased productivity of the personnelImproved safety of the system due to better information and improved control Protection of the plant equipmentSafeguarding the environment from a failure of the systemImproved energy savings due to optimization of the plantImproved and quicker receipt of data so that clients can be invoiced more quickly and accuratelyBenefits of SCADA systemRTUAn RTU (sometimes referred to as a remote telemetry unit) as the title implies, is a standalone data acquisition and control unit, generally microprocessor based, which monitors and controls equipment at some remote location from the central station.Its primary task is to control and acquire data from process equipment at the remote location and to transfer this data back to a central station.It generally also has the facility for having its configuration and control programs dynamically downloaded from some central station.There is also a facility to be configured locally by some RTU programming unit.RTU hardware structure Typical RTU hardware modules include: Control processor and associated memory Analog inputs Analog outputs Counter inputs Digital inputs Digital outputs Communication interface(s) Power supply RTU rack and enclosure

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. RTUs, having a capacity greater than this can be classified as large.RTU: Size and Capacity RTU: Communication and InterfaceThe modern RTU should be flexible enough to handle multiple communication media such as: RS-232/RS-442/RS-485 Dialup telephone lines/dedicated landlines Microwave/MUX Satellite X.25 packet protocols Radio via trunked/VHF/UHF/900 MHz