SCADA is an abbreviation for Supervisory Control and Data Acquisition and as such has emphasis on the supervisory level of the system. It is a software application that is positioned above the hardware of the system architecture and interfaces to it via a central control host and a number of Programmable Logic Controllers (PLC's) or other commercially available hardware modules. SCADA systems are ideally suited for the remote control of industrial and experimental processes and are available in configurations of hundreds of input/output (I/O) channels to hundreds of thousands of channels in some applications. SCADA is a rapidly developing technology that is penetrating many areas of remote and distributed control.

A typical industrial measurement and control system would consist of a central host or Master Terminal Unit (MTU), a number of Remote Terminal Units (RTU's) used to collect field data plus application software for the monitoring and control of all remote data sub-systems.

SCADA is predominately used in longer distance communications applications and utilises a variety of communications medium mostly in an open-loop control structure. Alternatively, the control structure may be a combination of open-loop and closed-loop control combined with elements of short distance control.

Distributed Control Systems (DCS) are also commonly encountered in production plants and smaller industrial processes including research and development areas. These are mostly closed-loop control systems that operate over a confined area and offer high speed communications over Local Area Networks (LAN) with high integrity.

Plant control may be automatic or manually controlled by operator commands. Data monitoring is achieved by the RTU's (PLC or process controller) scanning the field inputs at a fast rate. A specific RTU requires a sufficient real-time bandwidth for the monitored processes and has distributed intelligence to deal with the monitoring task. The MTU then scans the system at a slower rate looking for alarm conditions and reporting system status.

Monitored data is usually a combination of 3 types. Analog outputs may be acquired at fixed intervals with the results either trended graphically or updated as numeric values in engineering units. Digital data (On/Off) represents the state of switches or valves or even alarm conditions. Pulse data is used to count revolutions and determine the speed of rotating machinery.

The Man Machine Interface (MMI) is usually a graphical mimic display representation of the plant or selected area of the plant. The live data from the field inputs is superimposed on this static background and the foreground changes according to changes in the process. Operator awareness is heightened by the use of colour, animation and sound. The MCU will generate histograms (trending), control data logging and handle alarm conditions. Additional tasks may involve report generation, the archiving of data and data automation triggered by events.

SCADA Solutions

Expertise is offered in the design, configuration and implementation of SCADA based plant control systems. Customers can expect significant cost saving in the development and maintenance of a complex control process using this system. These potential benefits arise from the understanding of current industrial standards at both the client layer and the data server layer in addition to a system design approach that includes functionality, scalability, performance and openness.

SCADA design is implemented within an established framework with an emphasis on reliability and robustness to produce systems to the highest standards of performance for critical industrial processes. High quality engineering is paramount to achieving all of the above performance requirements and requires an organisation with experience that is familiar with new technologies and emerging trends in the area. The full range of services includes customer or end user training and after sales technical support and service.

Please view our Control and Automation page for further information.