While the intention of this article is to address the issue of scada (supervisory control and data acquisition) it is difficult today to separate scada from the other elements of the customary pyramid of modern manufacturing hierarchy, which would include the data historian, MES, ERP and so forth. In order to remain competitive in a global environment where e-business is the order of the day the entire system should ideally be linked so that, for example, order inputs to SAP trigger events at the manufacturing level where actions are also taken to plan, source, make and deliver according to the needs of the specific requirement in the order.
A brief search on the Internet with the key word 'scada' quickly reveals that there are more than 60 suppliers of scada/HMI, and more integrated systems. Only about 10 of these companies have a significant installed base in South Africa and this article is based on discussions with a few of the key players and gurus. These included true scada suppliers and those who offer more totally integrated solutions. As indicated while total manufacturing intelligence is the ideal it is far from universal so there are some conflicting views from these two groups of suppliers. Whereas scada was once just a visualisation tool, today it is being employed in a knowledge-based way, ensuring for example that devices like pumps are running at 100% effectiveness and providing trending information that can in turn be linked for example to alarms. By the way, it is a given that any modern scada system will be based on open industry standards facilitating customisation, expansion and ease of use.
In terms of the pyramid hierarchy there are scada developers who do not agree with this representation of the manufacturing environment. Adroit, for example, see all of the various levels from PLCs through scada to ERP as sitting on the same intranet/Internet backbone. Rich solutions can be implemented at every level and through the intranet one can talk from MES level directly to scada or even the PLCs. They also believe that the fully integrated solution is still somewhat advanced for smaller enterprises and indicate that 80% of sales still lie in requirements for scada/HMI. Remember that Adroit is the only South African scada system developer and its export sales comprise up to 40% of its business. This status quo of using scada as a basic HMI product is therefore global and not a reflection of the immaturity of local industry. With just this solution implemented the manufacturers use scada to produce key performance indicators that can be displayed to a much wider audience than before.
A generally held view and expressed in the opening paragraph of this article is that scada cannot be considered in isolation and most suppliers agree that a major development (already implemented by some suppliers) will be the seamless two-way movement of scada data up into the MES and ERP levels with links into SAP and other management reporting and control systems. For the multinationals or companies who operate several plants, breakdown within a specific plant can, using this fully integrated system, see the order transferred to another plant that has capacity. While the integrated system gives management an overall view of the plant's operations Citect as one example believe that the reverse is equally important. They ensure that this so-called 'boardroom' information is available to the scada operator himself so that he can see immediately what part of the process is not running at 100% efficiency, correct the fault and ensure that his company gets more out of the plant.
Siemens was at the forefront in introducing the concept of totally integrated automation (TIA) where a common database, engineering platform and communication pathways form an integrated automation platform. They are now taking this concept a step further with the integration of a full scope of MES packages and tools. In terms of scada they believe that their competitive differentiator is TIA with the immersion of the scada system into the automation hardware platform being a guarantee rather than a guess.
As for the operating system, it appears that Microsoft will continue to dominate. While other systems such as Linux or UNIX may be more stable in the manufacturing environment there is no customer demand to change, and to put it in a nutshell there are no open source skills available. People have become too familiar with the Windows milieu and there is no desire to change to something different. While Windows NT and 2000 are the most common operating systems in installed scada systems, there are users that are still using 95 while several suppliers have already made the transition to accommodate Microsoft.Net. It is believed that Microsoft.Net will allow the user to take full advantage of the Web as a network technology, where for example one could import data on a pump or valve directly from an Internet site.
Companies that already have their new Microsoft.Net scada system up and running include Citect. In order to avoid hassles and downtime at their installed sites, migration to the new system is being carried out progressively using parallel operation of the new and old system to ensure full stability before the latter is switched out.
To stay in business themselves, scada suppliers have to keep their offerings in line with the expectations of their customers. As one example, Wonderware conducted a survey of all its global customers and established that what was highest on the user's wish list was better integration. In its latest release, the Archestra application (every system in your plant operating in concert) they have introduced the 'unified' as compared to the 'integrated' application. Unified applications have access to a common repository of information that can be shared by all applications. As each application still needs its own application-specific data space any information that it needs originates from this global repository and likewise any information it generates is destined for the same repository.
A feature introduced by companies like ABB is the use of a device such as a Palm Pilot as an operator station. The engineer can then walk around the plant with this device in his pocket. This means that the massive control stations of the past can be reduced to virtually a single screen.
Security of course is a major issue and companies realise that the security offered by Microsoft is not good enough and they have their own firewalls and operator access only to the actual levels of detail required. However, once data is available on an intranet and over the Internet and information is freely available albeit with password and other protection, companies must bear in mind that they are opening themselves to determined hackers. If you want free flow of information then a lot of money must be spent on security and the possibility of hackers must be accepted and addressed. It should be remembered of course that most of the information being transferred (probably in excess of 90%) is plant data that is not particularly sensitive and here the security technologies offered by Microsoft are more than adequate according to most vendors.
The typical operator in the plant is a dying breed. In the past a technician would configure the PLCs or DCS system. Nowadays systems are open and are not configurable in the same way, so IT specialists are required who need to know the Windows environment backwards. Once the system is running, it is not operators that are needed, but process and business engineers, as the systems themselves have intelligence and can effectively run on 'auto-pilot'. These engineers of course now have much more to think about, as the amount of data available for them is immense. They need to be able to interpret this data to make the best process and business decisions.
All suppliers and customers are aware of the fact that operating software is continually in a state of evolution and most companies do not like the idea that while your plant may operate for a period of 20 years, software changes occur in less than 18 months. One trend now is to make the basic infrastructure independent of the operating system. While Microsoft.Net might be the flavour of the year for 2003, you still want your application to remain as it is when .NewNet appears next year. On the other hand, companies such as Adroit believe that Microsoft.Net will be around for some time to come (up to 10 years). Their argument is that Microsoft has learned its lesson and as the conversion to .Net is even more costly than the change from DOS to Windows, customers will be unwilling to accept further changes and costs. In fact, Microsoft.Net must be seen as a long-term solution and one that will be an incentive to make the change from older versions of Windows.
There is no doubt that scada is continuing to evolve as a knowledge-based system and that the common operating system will become Microsoft.Net. Although it is being addressed in different ways the common and ultimate objective is to have a very integrated total system that encompasses all aspects of the business. The customer himself must make the ultimate decision as to which of the many innovative systems being offered he should choose. Factors that must be considered are the size and complexity of the operation, cost and expectations.
Dr Maurice McDowell has many years' experience as a technical journalist, editor, business manager and research scientist. His third party analyses of world-class companies and processes, as well as his insight into industry and technology trends are well respected.
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