Ethernet grows but Fieldbus is alive and well!
Another year of information gathering is concluding with the issue of the communications reports. Ethernet, in its various guises continues to increase its share of the market. Just looking around at the publicity and products on view at exhibitions might lead you to believe that it will swamp the market in a few years and fieldbuses will be consigned to the history books. My view is that this will not happen; the evidence for a wholesale switch to Ethernet based technologies is not there. Sure a few companies have seen good growth, I don’t doubt that but node-for-node, Ethernet will gain a few per cent share over the next 5 years.
Figure 1 shows for fieldbuses and Ethernet based protocols, the number of nodes estimated to have been installed in industrial automation networks in 2010 worldwide. At first glance it seems that fieldbuses are expected to forge ahead but in fact their share of the total market is falling.
Figure 2 shows the forecast growth rates for 2011 to 2015 and these clearly show that Ethernet growth will slow only a little till 2014 then start to show signs of levelling off. Over the same period the fieldbus growth rate is expected to fall each year, picking up a little in 2015.
It may come as a surprise to some people that fieldbuses are still growing as fast as they are but there are several reasons why this might be.
- Ethernet has yet to make an impact at field level; despite high growth rate being reported, the actual numbers are low when compared to nodes connected at control and supervisory level. Ethernet is frequently seen as over complex for use at field level as well as adding extra cost to the device. There are a lot of devices at field level!
- Fieldbuses are generally much simpler to use.
- Fieldbuses were in common use 20 years before Ethernet was considered seriously for industrial use, hence there are a lot of legacy systems and the associated knowledge base.
- New “non-Ethernet” communication technologies and enhancements to existing ones are being added to the list all the time, e.g. I/O Link, AS-Interface, USB, FireWire etc. Some industries have their own favourites: machine vision has CameraLink and CoaXpress; building automation has BACnet and LonWorks.
- There are many proprietary communication technologies in use today. This is particularly true in Asia, especially Japan, where the adoption of Ethernet in industry has been slow.
So in conclusion; Ethernet grows but fieldbus is alive and well! All the signs are that this will continue for the foreseeable future. Ethernet and its many variants is another story, subject to its own set of rules and trends. Watch this space for the next exciting chapter!