Control Systems: Don’t Get Misled by Modernization Misconceptions

Six fallacies often undermine control system upgrades

By Mike Alsup, Emerson Process Management

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Many plants rely on control systems that are obsolete or on the verge of obsolescence. These systems can pose a variety of issues — from maintenance problems due to the difficulty and high cost of getting replacement parts to lack of features crucial for modern manufacturing — that can compromise the competitiveness of sites.


Some facilities want to upgrade but either aren’t sure what to do or can’t decide upon a course of action. So, here, we’ll provide some guidance.

As with any major project, migrating to a new control system presents a number of challenges. The plant must cope with ongoing issues with the existing system and an environment during that transition that differs significantly from that during steady production, as well as the possibility of unpredictable events and funding difficulties. Moreover, the entire process can take quite a long time — years of planning followed by days, weeks or more for the actual switchover.

PREPARING FOR A MIGRATION
No big project can succeed without adequate preparation. Proper planning is critical for success. That planning must include identifying all the needs going forward as well as limitations in available staffing, funding and other resources. One of the most important parts of preparation is to understand common misconceptions about modernizations. These can undermine a migration project and, in the worst case, prevent it from delivering the fullest benefits. So, let’s dispel a number of such misconceptions.

Misconception No. 1: My current vendor is the best choice to be my future supplier because it knows my current system. This is false logic. Success depends mainly on knowledge of the new system, not the old. It’s better to know the destination than the starting point. For that reason, evaluate all suitable suppliers.


Misconception No. 2: I don’t need to migrate because my current vendor guarantees support for another 10 to 15 years. This, in general, is false. For one thing, for many vendors the promise of guaranteed support of a legacy system is contingent on a whole series of mandatory upgrades (Table 1). Doing these simply upgrades more than 60% of the existing system to an interim system; the original input/output (I/O) cards, files and wiring remain, and the configuration hasn’t been touched. Extending the life of an existing system amounts to paying good money to stay with outdated technology. Consider an automotive analogy: Would you spend, say, $7,000 to put a new engine and transmission into a 1980s car? Even if you got a generous guarantee the new parts or even the whole car would last a decade, you’d still have a vehicle that lacks many modern safety, environmental, performance, usability and comfort features.