Legacy Control Systems Migration, Part I


One of the most serious issues currently facing plant/facility managers across all industries is that of legacy control system migration. What is this all about, and why is it such a serious issue? This post will be the first in a series and will address these specific questions. The term “legacy” was originally used (within the technology environment) to refer to in-place computers and software to distinguish them from newer systems being brought on line. The more contemporary meaning implies technical systems that have reached, or are approaching, the end of their reasonable life cycle, often because hardware elements have been obsoleted by the manufacturer (think no more availability of spares or replacements) or because software is no longer being supported with upgrades. By some counts, approximately $65 billion of process control systems, both PLC and DCS, fit this definition. Challenges Presented by Legacy SystemsFactors that need to be considered in determining a migration strategy include the following:

  • Discontinued hardware: When manufacturers discontinue a product, that means production of that item ends. The only access to replacement hardware becomes the secondary market of used items, such as e-Bay. These replacements tend to be expensive, and as the supply shrinks, the prices go up. Additionally, even with overnight express shipping, a manufacturing facility can lose a day’s worth of production tracking down and ordering replacements, potentially very expensive.
  • Unsupported software: It’s not uncommon for software producers to stop supporting older versions. Witness the recent announcement from Microsoft that it will stop supporting the Windows 7 operating system. When support ends, it means that bugs will not get fixed, new features will not be added, and help will not be available or will be difficult to come by. This may limit attempts to improve productivity, generate new reports, or expand user seats.
  • Security: Many legacy systems were installed long before the advent of widespread connectivity and the rise of almost recreational hacking. These system are generally lacking in basic security features needed to deter hackers, making them vulnerable to data theft and disruption of operation.

What is Migration? We typically think of migration as meaning complete system replacement. While this is the case more often than not, particularly if the fundamental issue is that of discontinued hardware, migration can involve upgrades of system sub-units, software replacement, or phased, as opposed to wholesale, replacement. The correct strategy for your situation will depend on the details of your particular system. Part II of our Legacy Control System Migration series will address migration strategies in more detail. Stay tuned. In the meantime, if you feel the time is right to start addressing your legacy control system issues, please contact us to learn more about our experience with multiple platforms and strategies and what we can offer in the way of turn-key migration services.