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As fieldbus market narrows, user experience widens

01 February 2006

Confidence in fieldbuses is growing; many users say they are planning to implement projects in the near future.

Arecent fieldbus survey conducted by the ARC Advisory Group under the direction of Larry O’Brien documents the movement of fieldbus from the ‘pilot application’ phase to an expanded presence in larger
and mission critical applications. It also shows that the process automation market has essentially narrowed down to two choices, Profibus and Fieldbus Foundation, although there is significant interest in the integration of existing HART devices at the I/O level with installed control systems.

The ARC study was a follow up to one conducted two years ago which had 62 respondents. The 2005 survey not only had a much larger base of 227, but was geographical regions and industry segments. Nevertheless, Mr. O’Brien cautions that he makes no claims that the results are ‘statistically significant.’

‘We do believe that the results corroborate many of our own views regarding the fieldbus marketplace and
are probably one of the best samplings of end user attitudes towards fieldbus technology currently available,’ he says. ‘Of course, these results do not statistically represent the collective opinions of the
hundreds of thousands of people currently working in process plants or directly with fieldbus technology.’

Edgar Küster, chairman of the Profibus Nutzerorganisation e.V. (PNO), presented the ARC figures to over 100 users at an event held at the Bayer Industrial Park in Leverkusen and provided PNO’s perspective on the
survey results.

Number of systems
‘The response to the question on installed plant size created a very interesting picture for both technologies
PROFBUS and FF,’ noted Mr. Küster. ‘At first glance, this picture appears to be identical: irrespective of the field bus that was selected, both systems are installed to the same extent, and without any significant differences, in small and large plants.’

To the survey question, ‘Which process fieldbus networks do you have installed or are planning to install over the next three years’ survey respondents had a choice of Profibus DP or PA, FF H1 or H2 (H2 is also called HSE for High Speed Ethernet), and HART I/O. In the installed base Profibus DP is clearly ahead of FF H1, 63% to 40%.

Mr. Küster commented, ‘We are extremely pleased that the figures that were forecast for both field bus systems were well exceeded. All have emerged as winners, some more clearly that others. The only exception: FF H2 fell well short of the target.’

‘HSE understandably had a small response rate, since only HSE linking devices are available now, not HSE
products,’ commented Mr. O’Brien. ‘Even without actual products available, however, close to six percent of
respondents stated that they had HSE networks installed in their plants, and almost one quarter of all respondents indicated they would install HSE within the next three years. Over 40 percent of respondents indicated they had H1 Foundation Fieldbus networks installed, with over 23 percent stating they would
install H1 within the next three years.

‘The results clearly show that Foundation Fieldbus H1 has cemented itself as the leading installed protocol at the field level for process automation applications. Similarly, Profibus DP has the leading installed base at the high speed control network layer. While there are HSE linking devices available today, products compatible with Foundation Fieldbus HSE, such as analysers, drives, and PLCs, must become more widely
available before HSE gains significant ground as a control network.’

Both FF and Profibus are using their strength in installed base to grow their ‘other’ networks. Profibus is using its strength in high-speed Profibus DP to gain installed base in its low-speed Profibus PA devices while FF is doing just the reverse: it will build on its strength in low-speed H1 to increase the installed base of High Speed Ethernet networks.

Mission critical
According to the two ARC surveys conducted two years apart, the user confidence in using fieldbus systems for ‘mission critical’ applications has grown dramatically. Mr. Küster calls it a ‘minor sensation.’ In 2003, only 4% of FF and Profibus users said they would consider deploying fieldbus for mission critical
applications; these numbers have grown to nearly 27% for both fieldbuses in the most recent survey.

Profibus DP understandably has a larger installed base in critical process applications because there are many PLCs and drives on Profibus networks. The penetration of Foundation Fieldbus H1 has been relatively slower and is limited to the process and batch industries. But H1 has a larger installed base than the process field level Profibus PA.

ARC’s mission critical question lumped together Profibus DP and PA, and Foundation Fieldbus H1 and HSE. ‘Some may argue against this bundling,’ says Mr. O’Brien, ‘but I think the point here is that the total combined installed base of Profibus is bigger when you include DP, while the installed base for FF is smaller since it is limited to process and HSE has no certified devices available yet, just linking devices. So, for example, you will not see an HSE-compatible analytical device on the market yet, but you can get one that fits Profibus DP. Adoption of device networks occurred at a much faster rate in the discrete [manufacturing] industries than did adoption of low-speed fieldbus protocols at the process field level.

The integration priority
The survey asked users to rate the selection criteria they used for choosing a fieldbus. They were given a choice of sixteen criteria, and for each one they were asked to rate it in one of six categories, ranging from extremely important, very important, and important down to somewhat important, not very important, and not
important at all.

To simplify the results, we have lumped the first three—extremely important, very important, and important—into one category ‘important’ and the last three into another category ‘not important’ (see Table 1)

Mr. Küster and the PNO say they were delighted that the top-ranking response was for the criterion, Integration of process fieldbus networks with device networks.

‘With an approval rate of 88%, the greatest significance worldwide is attached to the point Integration of
process fieldbus networks and device networks,’ he said. ‘For Profibus is the only universal, digital communication protocol to which discrete field devices and process instruments can be equally connected. All other solutions require a second fieldbus system and this has a negative impact in terms of the total cost
of ownership.’ [Additional data gathered by ARC after Mr. Küster made his presentation pushed the Improved
maintenance and Device interoperability criteria ahead of Integration, but all three are at the top of the list.]

Improved instrument maintenance (86%) and Device interoperability (84%) can also be found at the top of the list. Mr. Küster explains: ‘The PNO attaches great value to the latter. This is the only way that the field devices of the member companies can be inter-exchanged without encountering any problems.’

‘The fact that only a little over half of the participants categorised the Need for latest technology (53%) as being extremely important does, however, come as a great surprise.’ he says. ‘Almost 25% even go as far as to say that the latest technologies are superfluous. This is not something we did not know already. The users in process automation are known for their pragmatic approach which typically involves observing from a safe distance to see how others get on with their pilot projects.’

At the bottom of the criteria list is Control in the field, a function offered only by Fieldbus Foundation. Only 53% of the respondents believed this ‘embedded control’ function was important.

Mr. Küster says he doubts the benefit of this function and, outlining a possible reason for this trend, explains: ‘Speaking as strong Profibus proponent, this may well be attributable to the low data transfer rate which, in the presence of an error, does not allow Control in the field.

‘They would say that, wouldn’t they,’ writes Andrew Bond in his newsletter Industrial Automation Insider. He notes that the number in the ARC survey who think embedded control is unimportant is nearly the same as those who have installed Profibus PA. ‘If you thought there was value in embedded control or control in the field, you’d hardly install a Profibus PA network which doesn’t allow you to implement it.’

Mr. O’Brien thinks the control in the field functionality is a key feature for high availability, a way of avoiding unplanned downtimes which may be very important for critical loops. This is called ‘graceful degradation.’ But it is a specialised requirement, and most are installing fieldbus components today for the remote
diagnostics and predictive maintenance functions, not control in the field.

‘Embedded PID control has been a topic of contention among the fieldbus users,’ says Mr. O’Brien.
‘Embedded control functionality in field devices is one of the key enablers for achieving high availability control and a steppingstone toward single loop integrity.

‘Many do not see the value in field level control. For many of the more advanced users, however, control in the field is viewed as a path to high availability control and single loop integrity and as a result, they are running control blocks in many of their fieldbus devices.

‘The basic premise is that field level control takes over when the controller fails or is cut off from the field device. Many users have already managed to avoid unplanned downtime when field level control took over after interface card failures.’

Quicker ROI
Both fieldbuses perform equally well from an ROI (Return On Investment) community and process automation end perspective, and a substantial improvement has been made over the last two years. The 2003 study revealed that 11% believed in an ROI within just six months. Today, this share has increased to 27%. A further 18% put the ROI period at 12 months (Table 2).

Pleased at the development, Mr. Küster says, ‘A lot has happened here. And I clearly put this down to the
positive experiences that users have had with the technology. Having said this, the PNO Managing Board fairly admits that these laurels have been equally earned by both of the fieldbus systems.’

With regard to the initial costs a third of the users is convinced that the hardware and software costs, the
product costs and system costs of the field bus systems are slightly higher that in the case of a conventional system, a third believes that the old and the new are pretty balanced in this respect and the final third sees the advantages of the new technologies (Figure 1).

The result for installation costs is, however, completely different, notes Mr. Küster. The participants more or less unanimously agree on the significant price advantages that field bus systems offer, particularly in the commissioning phase. The verdict for lifecycle costs is even more clear cut in favour of the fieldbus systems. Mr. Küster emphasises: ‘We are very pleased that the users in the new fieldbus survey have made clear statements on how they benefit from field bus systems.’

According to Mr. O’Brien’s report, most respondents chose to go with a single source supplier for Foundation Fieldbus implementations, although there are few suppliers such as Siemens A&D and Emerson Process Automation who can offer both systems expertise and a wide range of field
instrumentation. Most users will likely continue to take the single source approach for both Foundation Fieldbus and Profibus PA installations. In most cases this involves a single systems supplier along with multiple field device and control valve suppliers, as well as an engineering partner. Many users are
increasingly adopting the ‘main contractor’ approach, where a single supplier partner acts as a sole point of
responsibility for managing the automation project, co-ordinating activities among the various automation
suppliers and engineering firms involved.

For Mr. Küster, the responses to the question on whether users of control systems and field devices prefer to use one single supplier or purchase components from various suppliers did not produce any ‘really surprising’ results.

‘The majority of the Foundation Fieldbus users opt for single source suppliers,’ he noted. ‘In contrast, most of the users in the Profibus world love the diversity in multi-vendor plants. Profibus is the only system that provides users with the possibility of selecting from the best DCS systems and field devices with
subsequent problem-free integration in one system.’

Positive results
Mr. Küster is positive about the results of the survey. It is ‘wonderful evidence’ for the increase in the number of installed field bus systems. ‘Sixty one percent of the participants are currently planning a new installation. Digital communication is, to a growing extent, also winning the confidence of the users in Mission Critical
Applications—an extremely positive finding. In addition, the process industry has recognised the importance of being able to integrate process instruments and discrete devices—a possibility that is offered consistently by Profibus with the profiles Profibus DP and PA. Moreover, the information provided by the users of the universal technology confirms its unlimited suitability for multi-vendor plants. The option ‘best of breed’ or ‘best in class’ also speaks for Profibus. In this way, the best of the best can be used through the harmonious interaction of many suppliers and a high degree of flexibility can thus be guaranteed.’

Mr. Küster admits: ‘It is quite possible that some facts appear to be particularly positive from a Profibus perspective. But one thing cannot be disputed: the results show that field buses have been successfully established in the process industry in the last few years thus paving the way for reduced costs and more

‘ARC has long stated that the real benefit of fieldbus technology lies in its ability to enable advanced asset
management and predictive maintenance strategies,’ concludes Mr. O’Brien. The deployment of a Plant Asset Management (PAM) application in fieldbus installations can help to realise this vision. The user awareness of the value proposition of PAM comes across in the survey results. Close to 60 percent of total respondents indicated that they either currently use Plant Asset Management applications in their fieldbus installation or are planning to use them.

‘Deploying fieldbus in a plant environment without utilising a plant asset management suite is like buying a
car with no engine. The diagnostics and device information available through PAM applications is an essential part in the value equation for fieldbus deployment.

‘Remote diagnostics and maintenance capabilities continue to be primary selection criteria for most users that purchase fieldbus control systems. In ARC’s view, however, most users do not follow through on the asset management capabilities of fieldbus when used in conjunction with a PAM application. Too much time can be spent focusing on the initial cost of a project and the reduction of capital spending than the cost of ownership of return on assets (ROA) that can be achieved using PAM and fieldbus.’

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