Is backwards compatibility holding us back?

Wanting to retain current field hardware and use our existing skillsets may soon start costing us more than we should be willing to pay.

By Ian Verhappen

We always require backwards compatibility with any new control product, which is certainly beneficial for these reasons, and likely many more: the interface to the control system doesn't change (this is why HART 7+ devices are able to work with HART 5 devices); spare parts and inventory (only necessary to keep one of each type rather than revision-specific models); training (they work like the old ones, so no new skills are required); and engineering systems—loop drawings, data sheets and all the work procedures to generate the documentation to build and maintain the system—are well established.

However, despite all these good things, is backwards compatibility also preventing us from taking advantage of new technologies? Recent news of the ExxonMobil initiative, which I understand now has 16-plus end user companies and approximately 60 suppliers expressing interest, indicates there is some desire for a different approach. A chance to review the presentation from ARC in more detail has made me wonder if our traditional boundary conditions are preventing us from taking advantage of technology and the associated benefits. Here are a few examples of how staying backwards compliant have held us back from bottom-line benefits:

Control system interface: I believe this was Foundation fieldbus’ Achilles heel, and why most installations are for greenfield facilities. Organizations could not afford to replace all their field devices and associated infrastructure of junction boxes, power supplies, barriers, etc.

Spare parts and inventory: this is part of the reason that we're not taking advantage of the intelligence of HART devices by connecting them to asset management tools in more than, the last I heard, about 20% of installations, as each revision adds new parameters, and we don't have the tools in place to manage this change (though ISA108 is working on it, and resulting in more efficient maintenance practices).

Training: No need to learn more than the basics of my handheld communicator to set and change the range or run the partial stroke test wizard, because this makes my job easier.

Engineering systems: I know how to run and configure my “XYZ System” for these devices and the programming language for the associated applications. It would be a huge effort to change all these to a new platform, and who wants to pay to do that? Some companies have made the investment and seen the benefits—one need only look at recent Plant of the Year winners for examples.

Recent news of the ExxonMobil initiative indicates there is some desire for a different approach.

Despite the above list, I believe we've demonstrated that backward compatibilities can be a matter of degrees. Field devices connected to the process are likely to be expected to have a similar lifespan to the pipes and vessels, while it could be argued that operator displays like our desktop computers have a much shorter lifespan. Of course, over the life of a facility, it's highly probable that the individual field device may be replaced multiple times simply due to wear and tear. And as long as the interface with the primary process variable doesn't change, it's considered backwards compatible—or at least close enough.

Some of you may recall past attempts by other organizations, such as GM, for full open systems. They had initial enthusiasm, but didn't get much beyond that stage. However, this time around, our control systems are increasingly relying on open, commercial technology with much of the differentiation and intellectual property (intelligence and knowledge) residing in software. We're also now connecting more devices with Internet Protocol-based networks, and there are several consortia working on connecting everything to everything else using the Internet of Things. One could argue that our next-generation control system is simply another combination of things.

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It's certainly an exciting time to be in the automation and controls community. One thing that's certain will be change. Whether that change is reflected in the vision being proposed by ExxonMobil, one of the Industrial Internet of Things consortia, or, as is more likely, some combination of them, the lost opportunity of remaining with the status quo is becoming too large to ignore. Full backwards compatibility for all control system elements should not be the reason to hold back.