July/August 2010

Your Letters

Fieldbus/Ethernet integration

I read with interest Ian Verhappen's "Integrating the bus" article (March/April InTech) on the integration of fieldbus protocols to Ethernet architecture. I think there is great promise in the use of Ethernet as a means of transmission for the fieldbus communications. I believe, as Verhappen stated, that by using Ethernet architecture as the backbone of the fieldbus, the cost of installation and maintenance can be reduced. I would like to see the industry focus on the fault tolerance capabilities of the fieldbus loops to improve the communication reliability. I have commissioned both Profibus and Foundation Fieldbus loops over the past eight years. However, I have found that the "cost savings" that the vendors preach of reduced wiring and installation expenses might be achieved only once you saturate your fieldbus loop to its device capacity or the instruments are within arm's reach of each other. The issues I have seen with fieldbus systems are their susceptibility to failure and the confusion created in the maintenance department when service is required. The Foundation Fieldbus loops I have commissioned were in a power plant environment communicating with the plant DCS. As these loops were commissioned and the process begun, there were several reliability issues we experienced. It took great lengths to "harden" the loops to provide dependable operation. The hardening consisted of redundant power supplies and short circuit tolerant termination blocks. I still feel that these control loops are exposed to greater risk of failure since the devices are all connected by just one cable. The confusion in the maintenance department comes from the lack of experience with digital instruments. Most experienced instrumentation personnel are most comfortable with the analog and/or HART communications protocol. I tend to agree with them in that it is easier to connect to a device in the field with a HART communicator and immediately see the process variables. Our Foundation Fieldbus instruments require some investigation and digging to reveal the process variables, and this makes the technicians uncomfortable as they are troubleshooting. I do believe that an Ethernet-based architecture and one communication standard would simplify the training and skill requirements for the field technicians and improve process availability. If the industry will focus on fault tolerance, ease of use, and cost savings of the Ethernet backbone, then it will have a chance of becoming the next standard in the process control industry.

Dennis Fairchild

Overall standard of living

I finally had a moment to read Hans Baumann's "Opportunity for valve innovations" article in the March/April InTech, as I have been travelling almost non stop. I thought the article was right on and especially enjoyed the data on the contribution of factory employment on the balance of trade. Actually, I think you could make a case for the overall standard of living in a country on this basis as well-i.e., the standard of living in a country is a function of the aggregate efficiency of all the markets in that country, something that does not bode well when our economy is becoming two-tiered with a high incidence of service sector jobs. It is unfortunate that the folks making the decisions (the politicians) make decisions based on pure politics, not on any economic or engineering merit. As a result, the decisions are not based on either physics or economics and are either just wrong or are short-term oriented.

The Founding Fathers were all business people and were focused on what would make the country strong over the long haul, certainly a far cry from our current situation.

I also thought Baumann's observation about valve technology being really old was right on. After being out of this market for 25 years, I was shocked at finding that there had been no real breakthroughs in all those years. The companies still offer essentially the same valves! It is also true that risk-adverse management will not sponsor true R&D, and would rather just copy some other company that put up the money and created the atmosphere to do the research. After being in the electronics market all these interim years, the lack of customer centricity and aggressive pursuit of new useful products in this industry is staggering. Perhaps this is because there have been few significant changes to the industrial processes in this period of time, so that new product development has focused around digital electronics, where technology has advanced a great deal.

Normally, this would mean that there should be opportunities for creative folks to blaze the trail with entrepreneurial products.

Carl Reed