ONE OF THE remaining hurdles to the adoption of fieldbus technologies in the automation and control realm is that many of the engineering procurement construction (EPC) firms that design and install facilities dont include fieldbus in their proposals.
Part of the reason for the reluctance to make this change is just that; it is a change with all the apprehension and baggage associated with those events. Change also comes with expenses for such things as:
- Work Processes
- Design Tools
ProceduresSystems in place defining how something is to be done will have to be modified to reflect adding this new technology, depending on the number of fieldbus types being considered. In many cases, if fieldbus technology is selected for a project, no one fieldbus is capable of meeting all the I/O needs, and so multiple buses, plus traditional analog or discrete signals, must be combined in one system. New ways of keeping track of which type of signal is doing what need to be developed. This leads to related changes in
Work ProcessesThe amount and type of interaction between engineering design teams is different in fieldbus, especially if you want to support field-based control. This means that the process engineers need to sit with the automation engineers to confirm the interactions between field devices, while the electrical engineers need to discuss physical equipment locations to minimize cable runs and installed costs, and the instrument engineers need to specify the actual devices. Fortunately, automation and instrumentation folks often are the same person.
The team also needs to determine who on the team is doing what task. With the field devices and associated field termination equipment now part of the control system network, for example, should the design of the cable and I/O be done by the electrical or instrumentation staff?
Design ToolsNew design tools are required to calculate the limitations and layout of these new networks.
CalculationsTraditional point-to-point systems were only concerned with having enough energy for one device. Now designers not only have to consider the energy at multiple devices, but evaluate other rules and limits on other items, such as total cable length, cable terminations, communication resources, and network cycle times necessary for the data to be collected. Fortunately, a selection of helpful, free tools is available from several suppliers, though each has its own limitations.
TrainingTo gain new skills, of course, users require training to learn and apply them. Unless a large project is willing to include training in its costs for using new technology, this requires an investment in unbilled time, which reduces profitability by increasing overhead. In addition, once new skills are learned, experience shows that designing fieldbus systems requires fewer hours than traditional point-to-point analog controls, which further lowers installers invoice and revenue, and makes their initial problem bigger.
This difficulty is compounded by the fact that, despite what we who have seen the light like to think, instrumentation and control is not a core component of most EPCs, but is instead a support service needed for selling the bread and butter of process and mechanical engineering. Of course, the automation suppliers, for whom this is a core competency, are filling this void by becoming, not only host system suppliers, but also complete automation suppliers responsible for everything from the field device through to the control system and the final control element.
However, not all is bad news. The good news is that some end users are forcing EPCs to include fieldbus as a deliverable, and some companies are learning these new skills. In addition, some EPCs believe having fieldbus-capable staff is a competitive advantage for bidding on projects, and for recruiting and retaining their staff. Some are investing in bringing these skills into their organizations through training or subcontracting arrangements with specialists. In fact, some institutions worldwide are offering fieldbus training, so interested organizations can obtain vendor-neutral introductions to the technology.
After this latest design hurdle is crossed, the next and close to last one remaining is the installation contractors. That, however, is the topic for another column, and one well discuss in the near future.
In the next column, we will talk about Industrial Ethernet and what that term really means. As always, your comments and suggestions on the above, as well as input for future discussion topics are encouraged. Please contact me at the information below.
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