Does the process industry really need ethernet?
Differentiated Industrial Ethernet applications in the process industry

The high profile of Ethernet at this year’s Interkama, in podium discussions and in the press is a good indication that the technology has finally arrived in the process industry. However, it is important to understand where exactly Industrial Ethernet is being used, as there are segments of the market which are not ready for this technology.

thernet is one of the hot topics in the process industry. The technology is actually not new, as it has been used in the manufacturing industry for twenty years. The current interest in the process world stems from the fact that Ethernet can provide a seamless link to the enterprise management level. It also offers other advantages including enhanced topologies, higher data rates and better performance. However, it is important to understand where Industrial Ethernet is actually used in today’s plants.

"Up until now, deployment of Ethernet has been limited to communication between a control system and other control systems or the enterprise management level," explained Peter Wenzel, General Manager of the Profibus User Organization (PNO). Ethernet has largely replaced proprietary systems which were used for communications between control systems, MES systems, package units, HMI communications, etc. "It provides a platform for non-proprietary communications between the systems," commented Hasso Drathen, General Manager at Namur, an international user association of automation technology in process industries. He believes that the penetration level of Ethernet will increase in many areas. "Most process plants have systems which for the most part handle discrete input and output signals and use a lot of manufacturing technology components" said Wenzel. "Raw material storage, packaging, filling and palletizing systems for finished products and material handling systems including their drive and control components are typical examples. An Ethernet interface can quickly be provided for new and enhanced versions of these components using Profinet for example."

Focusing on the field

However, the process manufacturing industry is process-based, and Drathen, speaking on behalf of users, does not mince his words about the prospects in this sector. "I do not see a need for Ethernet at the field level in the foreseeable future."

There is currently no coherent strategy for using Ethernet in the market segments which are addressed by Profibus PA and FF. Wenzel summarized the current situation as follows: "Low-energy, bus-powered components are the solution of choice in these applications, for example Profibus PA. State-of-the-art Industrial Ethernet solutions such as Profinet can be introduced quickly on discrete automation equipment, but Fieldbus solutions like Profibus PA are likely to dominate in the process segment for a long time."

In general, it is questionable whether there is any need for Ethernet at the field level. "The disadvantages of Ethernet at the field level include high cost per connection, a relatively low data volume per field device and moderate reaction times. There is no need for the high bandwidth which Ethernet can deliver," emphasized Andreas Hennecke who is the Product Marketing Manager for Fieldbus Technology, FieldConnex at Pepperl&Fuchs. In his opinion, two essential issues need to be addressed, namely how to supply power to the field devices and implementation of explosion protection. "Current Fieldbus technology such as H1 and Profibus PA use a common cable for power and data, and this also reduces installation effort and cost. Maintenance has to be carried out on field devices during ongoing operation. You have to be able to disconnect circuits without a fire certificate. Fieldbus technology already offers a proven solution."

Ernst Jäger, Asset Optimization Sales Manager at Emerson Process Management, believes that Ethernet is suitable for all applications that have a communications protocol as long as installation costs are appropriate and explosion protection requirements are met. "We have been using the technology in process control systems since 1996. The real challenge is the creation of standards that define interoperability between devices, host systems and applications." He added that wide-spread market acceptance will only be achieved if the equipment is easy to use and due consideration has been given to the critical maintenance issues. In other words, there is no point in introducing a technology if the costs for installing the equipment and providing the necessary infrastructure are not attractive from a business standpoint.

Drathen shares this view. In addition to issues surrounding safety (explosion protection, IT security and SIL requirements) and availability, he believes that cost efficiency is a problem. "The established PA and FF field bus systems along with Hart communications work very well. Ethernet offers neither added value nor cheaper field devices, and it has the disadvantage that more spare parts are needed."

Simplified integration

With these factors in mind, Wenzel talks about a replacement for existing systems. "The introduction of Ethernet-based communication at the field level in the process industry will not signal the end of existing Fieldbus systems like Profibus PA. Instead, it will provide seamless integration." The proxy concept was a major aspect of the Profinet development effort. Protection of user investment was the primary concern. It was important to ensure that partial or total transition to the Ethernet world would be possible with putting past investment at risk.

According to Wenzel, other major issues will have to be addressed before Profinet can be introduced on a widespread basis in process applications in the process manufacturing industry. The list of challenges includes device integration, maintenance, diagnostics, configuration changes and high-availability system architecture. Dr. Heiner Röhl, Manager of the Industrial Communication Business Unit at Siemens Automation and Drives (A&D), added that "issues such as system redundancy, engineering, time synchronization and time stamping will present real challenges to the PNO working groups during the coming two to three years. In parallel with this development activity, Profibus profiles such as RIO for process control, weighing and dosage devices, intelligent pumps and lab devices are being modified for use with Profinet. Suitable network gateways are already available to connect the "PA world" to Industrial Ethernet, and the advantages can already be exploited." The work is expected to be complete by the end of 2008.

Practical implementation

Nevertheless, there is a high level of interest among users in the process industry. André Fritsch, Remote I/O & Fieldbus Technology Product Manager at R. Stahl, described what he has experienced so far as follows. "A lot of users want to know more about the opportunities as well as the risks which are associated with Industrial Ethernet." He believes that introduction of Industrial Ethernet in the process industry will lag behind the manufacturing industry by several years. However, "we expect that the first pilot systems will go into operation in the near future".

Potential applications

Beyond the field domain, there are other potential applications for Ethernet technology. "Ethernet connectivity could support the deployment of sophisticated instrumentation and fully pre-installed subsystems," explained Hennecke, and that is just one example. "Intrinsically safe Ethernet using new isolators is particularly suitable for mobile machinery and equipment or temporary installations." Solutions could even be developed for applications where a cable fault might represent a significant risk.

The process industry is not a homogeneous entity. There is a very wide range of requirements and investment strategies, and introduction of Industrial Ethernet in the process industry will depend on the different investment cycles. Röhl pointed out that "the oil and gas industry for example thinks in terms of 20 year cycles and is not likely to be the driving force behind Ethernet technology in the process industry. However, a lot of products in the food, tobacco and beverages industry such as yogurt or cosmetics have a one-year life cycle, and production systems have to be modified frequently. As a result, Industrial Ethernet has already become an established technology in these industries."

Fritsch believes that hybrid systems offer the greatest potential. These systems use Fieldbus (FF H1 or Profibus PA) and conventional field device technology (for example remote I/O systems) along side of Ethernet communications (Profinet or FF HSE). In his opinion, the chemical, petrochemical, oil & gas and pharmaceutical industries are typical users of high-performance bus systems which must be suitable for explosion hazards zones. Industrial Ethernet is predestined for applications where large volumes of data have to be transferred in a short amount of time and especially in applications where users want connectivity to ERP or asset management systems."

Summary

Industrial Ethernet will be used to an increasing extent in process automation but not in traditional field applications. Users are currently satisfied with the existing bus systems such as PA, FF and Hart. In general, Industrial Ethernet will have to address the usual requirements in the process industry such as safety, system availability and cost. Users will want to know what value-add Ethernet has to offer. Nevertheless, the two large fieldbus organizations, Profibus International and the Fieldbus Foundation, are working intensively on Industrial Ethernet for process automation, and working groups are developing solutions. It will not be long before these solutions show up in practical applications. Fritsch is convinced that "once automation systems offer Industrial Ethernet support on a widespread basis (and that is something which is lacking today), practical applications will soon follow. We assume that by 2009, Industrial Ethernet will no longer be a hot topic, because the technology will be widely available." This will undoubtedly be the case at higher levels in the IT hierarchy. Röhl is sure that "seamless communications in the process industry from the field level and DCS systems right up to enterprise-wide information systems such as MES and ERP will offer users significant value-add. Because Ethernet already plays a significant role in upstream and downstream automation applications, we see significant potential for successful deployment of Industrial Ethernet in the process industry." Drathen confirms that users agree with this view and are convinced that Ethernet offers significant benefits. "Industrial Ethernet will be used to an increasing extent for communication between PLC, process control and MES systems."