Article

By Valerio Alessandroni

In the industrial world the distance between management systems and hardware and software supervision and control systems is constantly increasing, making both mutual exchange of information and a uniform point of view difficult.
Let us consider the concept of real time, for example. In the case of production equipment, reactions within a few milliseconds are often required; in man-machine interface (MMI) and supervision (Scada) systems one passes to seconds or tens of seconds, while management systems (well represented by ERP - Enterprise Resource Planning) actually operate on a daily or weekly basis.
Another major difference is the size and cost of the programs: while an application for controlling a machine can cost a few million, it is easy to reach a billion Lire in the case of an ERP system with several stations. All this necessarily leads to reasoning on the basis of different methodologies within the same company.
To overcome these and other lacks of continuity between the various systems used in the industrial area, United States company Arc Advisory Group has proposed the definition of a new software layer placed between the ERP level and the MMI/Scada one. Called EPS (Enterprise Production Systems), they have limits that are still vague and are often typified by made-to-measure solutions, both because the reference models are not uniform and because the suppliers have to face considerable difficulties in succeeding to create products able to meet the needs of different sectors with different requirements.
In particular, up to now EPS software suppliers have had to devote the majority of their resources in creating and updating interfaces with systems at a higher (ERP) and lower (MMI/Scada) level. But new standard infrastructure technologies (e.g. the Microsoft Distributed Internet Architecture) and the latest generation of object and component technologies are allowing them to concentrate more on the offer of added value for specific vertical markets.
"Various acronyms have been proposed in the past in an attempt to interface the ERP level with the MMI/Scada one" states Mario Borali, Product Manager of the Automa company of Pedrengo (BG). "Among these the acronym MES (Manufacturing Execution Systems) is the one that has had the widest spread. However I think that the term EPS will replace MES, which is much more limiting". According to Borali, in fact, the MES represent only part of the EPS systems since they are principally aimed at the manufacturing area. But automation also involves many other sectors such as structural monitoring, safety and security networks (unauthorised access and fire prevention systems), remote control, remote surveillance and so on.
"Even the concept of a 'standard package', proposed by some suppliers for the MES and now for the EPS, is paradoxical in itself because these applications are too diversified to be handled by a single application package: the requisites of a MES or an EPS for a bottling plant, for example, are different to those of a MES or an EPS for the timber sector" continues Borali. "So it is preferable to speak of platforms for the MES or the EPS, namely tools that can be used by those who develop software applications for industrial automation".
For its part Automa has introduced a solution named Dolphin. "Being configured as 'in-field middleware', Dolphin facilitates the connection between MMI/Scada systems and database oriented applications typical of the EPS environment" states Borali, "allowing the development of applications such as data collection, production management, total trackability and traceability of production batches, works order management, etc.".
Software developers can use the Dolphin level in total independence, without constraints from the platform below. In fact, due to its nature, Dolphin can connect with various MMI/Scada technologies. To this end it is provided with a communication capacity (e.g. through OPC Server, the most widespread Scadas and the MicroC driver), specific functions (MMI node data transfer, conversion, processing and management) and interfaces (to exploit the aforementioned functions using database tables, D11, ActiveX, VBA, DDE and MicroC). Another important feature of Dolphin is the events/actions driver: this is a very simple programming system which helps to define a series of events to be scanned and the actions to be taken to be defined as a result of these events.
Thus it is now possible to attain greater integration between industrial information systems even if, in practice, the solution to the problem is not always easy and, especially in larger companies, a considerable gap remains between ERP and production. Thanks to the new EPS level (which Arc predicts will expand greatly over the next few years) one can, in any case, begin to put the pieces of a uniform, cohesive mosaic together, leaving space for the various technologies that typify the hardware and software architecture of industrial automation.