AccessMyLibrary provides FREE access to millions of articles from top publications available through your library.
Scada vendors have been quick to incorporate ActiveX, SQL etc to enable Scada systems to be developed into full MES solutions, explains Gert Rohrmann of Siemens Automation & Drives.
Although there is nothing new about the concept of Scada (Supervisory Control and Data Acquisition) the application of totally integrated automation, at all levels of plant control, is something that is only just becoming possible now. Scada technology seems to be improving at a more rapid rate than ever, although this probably has more to do with Microsoft than any of the traditional Scada vendors. Scada has been around since the 1980s and the decision to use this approach to acquire data and manage manufacturing processes was usually based on the complexity of the plant and the number of I/0s required. However, complex control requiring hundreds of inputs and outputs usually meant adopting some form of distributed control system, but these are seen by many as over complicated, unfriendly and inflexible. Many PLC (programmable logic controller) vendors and software houses developed perfectly good Scada systems as far back as 1980, but their power and usability was always governed by the choice of operating s ystem and the development of what was usually proprietary software and hardware.
A CASE FOR WINDOWS
With the advent of Windows, the role of Scada changed forever. We now have a standard operating system which, like or loathe it, is the de facto standard in the majority of companies around the world. With the development and adoption of Windows came a number of protocols - including ActiveX, ANSI C, SQL and ODBC, which can be very powerful Scada tools. Companies who are already established Scada vendors have been quick to incorporate the functionality offered by these protocols to enable Scada systems to be developed into full MES solutions. The concept of control from shop floor to boardroom is, perhaps for the first time ever, a reality. Companies such as Siemens, who claim their WinCC to be Europe's leading Scada product, are now providing hardware and software, running under Windows NT, which provides seamless integration at all levels of plant control.
PC BASED AUTOMATION
The adoption of Windows brings with it a number of important benefits. First of all, most people are already familiar with it. Secondly, it provides an open platform onto which one can build a truly integrated solution. No longer is a user tied to a single vendor. Hardware from one manufacturer can communicate with the PLCs of another and software from yet another.
While Windows has changed the face of process control, another development has been taking place simultaneously which has also prompted change among Scada manufacturers and users. According to Gert Rohrmann, Scada Product Manager: "Vendors are now offering PC based alternatives to the traditional, hardwired PLC".
A STANDARD SYSTEM
The real question is whether Windows NT and a PC are able to cope with all the problems a Scada system is likely to throw at them.
Users requiring high levels of customised control can use ActiveX or OPC to engineer a solution. Windows NT provides a future proof operating system platform because it will be supported by Microsoft. Soft PLCs developed to run under Windows NT, such as the new Simatic WinAC, do not use any proprietary real time kernel extensions, so there will be no problem with compatibility with Windows 2000.
Company name, location, telephone and fax number System scope ABB Automation; Stevenage, Hertfordshire. c Tel: 01438 742366; Fax: 742367. Adroit Technologies; Nantwich, Cheshire. m s Tel: 01270 627072; Fax: 629399. APV UK; Crawley, West Sussex. m s b Tel: 01293 527777; Fax: 552640. l p e Bristol Babcock; Kidderminster, Worcestershire. tv l Tel: 01562 820001; Fax 515722. p e Canongate Technology; Edinburgh, Scotland. tv l b Tel: 0131 455 7211; Fax: 7928. l p e Citect (UK); Peterborough, Cambridgeshire. tv m Tel: 01733 404850; Fax: 404851. l s Data Systems & Solutions; Gateshead, Tyne & tv i Wear. Tel: 0191 499 4100; Fax: 4001. s e Data Track Technology: New …