Best Strategy to Legacy IT Systems Migration and Modernization

During the last 3 decades, a significant amount of software has been established based upon obsolete technologies (such as using procedural languages). This type of systems has actually undergone severe code modifications throughout a long time period. As a consequence, the high level of entropy combined with inaccurate documentation about the design and architecture make the maintenance harder, time consuming, and pricey.

Reasons to Upgrade

Although a reasonably small portion of the total investment in processing plants, automation systems can have a huge impact on the successful outcome of the project and return of the investment throughout the lifecycle of the center.

In many cases, there are specific motivations for moving or replacing an obsolete control system, as well as enhancing the security of the control network facilities. However, not all motorists will apply to all sites. In general, they consist of:

  • Obsolescence– cost of supporting older generations of system elements and decommissioning withdrawn parts.
  • End of service life– changing equipment experiencing end-of-life concerns due to rust or age.
  • Future-proofing system components– need to lock-in vendor support for base hardware and software.
  • New units or upgrades– adding or improving an unit to guarantee it is a viable long-lasting solution.
  • Loading problems– current systems nearing their performance capabilities.
  • Amalgamation of operating consoles– enhancing operator performance in the main control room.
  • Cross-unit closed-loop control– ability to loop several control networks and systems for cross-controller control.
  • Cost decrease– lowering footprints and boosting controller performance.
  • New value-added features– consists of improved alarm management, operator effectiveness and asset management solutions.
  • Co-existence with multiple suppliers and applications– might not be possible or quickly finished with older system components.
  • System security– separating the HMI and controller level from viruses discovered in upper level networks.
  • Process data at the desktop– providing a protected course for required data that enables improved decision making at business level– producing real operational agility.

Migration Strategy

Effectively planned and implemented, control system migrations enable commercial companies to move legacy control platforms at their own pace, enabling new controllers to be added at any time and incorporated with existing devices. They also permit the upgrade of subsystems and function blocks to new controllers whenever the user chooses.

Once a migration project is determined, numerous vital areas frequently define whether the work is effectively completed relative to scope, schedule and budget plan. Success typically depends on an optimum migration strategy. A structured, organized method to upgrades boosts the benefits of new technology and protects the rich copyright contained in legacy systems.

Despite vendor support, plant workers must play an integral part in the effort, reviewing its progress every step of the method.

Just like any large, complex project, it is essential to do your research prior to, throughout and after the work. The key parts of a migration strategy are the process meaning and functional requirements files, specified at the start of the work. When detailed planning is not completed prior to starting the project, everything takes longer than expected.

To guarantee a successful migration effort, plant management need to prepare for the modification, recognize a critical timeline, conduct regular (maybe everyday) meetings, engage those who will be affected by the modification, identify all offered resources, and prepare for contingency resources or vendor staff, if needed.

A formal migration plan determines migration and support strategies for existing control system nodes, such as controllers, HMIs, supervisory computing nodes, etc. It also consists of proposals for consolidating existing control systems in order to reduce costs and enhance safety. Additionally, the plan offers recommendations for guaranteeing the reliability, effectiveness, security, expandability and
ease of diagnosis of process control networks.

As part of good engineering and project management practices, plants ought to take the following steps during migration planning:

1. Determine the very best time to migrate
2. Determine the very best migration course related to clearly defined goals
3. Specify the project through front-end engineering
4. Use a proven technique with extensive lists
5. Develop detailed cutover plans
6. Specify intermediate operability and training strategies

A crucial element of the migration process is a modernization evaluation for the existing DCS installation. The goal is to help preserve a control system that is stable, well supported, permits future development and enhances robustness. This evaluation will allow the plant to produce a migration strategy that reduces impact on operations (i.e., no production interruptions needed) while upgrading aging control system elements (i.e., HMI) in order to minimize functional reliability risk due to obsolescence and provide future growth capability with modern technology.


Choose the best methodology

There are numerous possible strategies to DCS migration, ranging from replacement of particular parts of the old system, to the setup of a full new automation platform. Some execution concerns can be difficult and likely add to the reluctance of many websites to face up to the need to move.

Industrial centers should take care to select the migration methodology best matched to their certain requirements. No single strategy is appropriate for all operations. Typical migration options include:

  • Phased migration:  Allows system modernization in steady steps, replacing the HMI or a specific unit initially. As soon as this is finished, completion user can benefit from options enhancing operations and safety. The remainder of the system can be changed over a number of years.
  • Complete replacement: Allows the whole system to be replaced at one time during a planned failure. In some cases, hot cutover can be used to decrease downtime and ensure smooth integration of present control possessions.
  • System upgrade: Allows an upgrade of important system elements at the end user’s own pace. The control system vendor have to be dedicated to keeping the value of existing systems and continuing to offer parts and support for the legacy platform.


Regularly, when a system needs modification, changing existing controllers also makes financial sense. For migration, 2 critical functions are needed: the existing field signals have to be quickly and rapidly transferred to the new control system, and the existing control schemes should be moved (and ideally improved).

For a massive retrofit, it is commonly best to use a phased migration. This strategy eliminates danger by incrementally narrowing the focus, while offering a fallback position to the old system. It needs communication with the existing system for interim phase-in, physical co-existence with the old equipment to allow a hot cutover, and the ability to switch effortlessly in between old and new signals for testing/tuning functions.

Phased migration does have its disadvantages, however it is a lower danger approach with less downtime. Additional danger and downtime reduction can be accomplished by mimicing the new system prior to setup. With phased migration, the control system is in a transition state. This implies the appropriate scope needs to be selected for each stage so that completion user can stop at any point in the migration and still have
a supportable system.


Choose the Right Partner Organization

Effective control system migration does not end with a single modernization project. Industrial plants require a cost-effective method for maintaining current process automation performance and lessening threats associated with system upgrades. Scalability is also crucial.

Continuous control technology development is the goal of a lifecycle management program– accomplished by developing a dedicated automation roadmap that results in either electronic refresh or full migration. Lifecycle support enables plants to start down the course to modernization today, and development incrementally as needs and schedules dictate.

A lifecycle management solution need to provide flexibility in how companies handle their plant possessions and predictability in how their choices are financed, consisting of the freedom to pick when to improve and surpass their control system, how to money the change, and how long to preserve current capabilities. In this way, companies can successfully extend devices life while providing a.
safe path forward to the current advanced control technology and capability.

End-users need to partner with an automation vendor providing multiyear support contracts that guarantee parts accessibility and support until a modernization takes place according to site operating plans. Such agreements lead to predictability by providing:

  • Predictable expenses for spare parts, support contracts and migration/upgrade kits.
  • Reduced danger and increased reliability through ensured maintenance.
  • Long-term protection from equipment obsolescence.


In addition, suppliers need to provide easy-to-implement migration tools that can conserve time and money. This includes tools helping database migration and integration, along with wiring kits to minimize downtime while moving legacy setups.

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