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When Do You Migrate a Legacy Control System

When Should You Migrate A Legacy Control System?

At one point or another, all controls technicians and engineers have struggled with making a judgment call to migrate a legacy PLC or HMI system to the latest software and hardware platform. There are many variables in this decision-making process, some are obvious, some, maybe not. Careful consideration will make it apparent when it is time to upgrade your system. Legacy control systems are a thorn in everyone’s side. Keep the end goal in mind, building a digitally transformed automation environment for your company.


Technology Advancements-

The one obvious indicator when considering a migration is that there will be an increase in functionality and capability of your systems with the latest and greatest advancements in technology. Migrating your control system will increase its capability and overall efficiency. For example, let’s say that there is a high-speed production line in your facility that has recently had a mechanical upgrade by the OEM. This upgrade has increased the production capability by fifty percent, but in order to achieve these numbers, the PLC code must be modified. While making the changes, you find that the scan rate of the legacy PLC is incapable of reaching the full potential of the mechanical upgrade. This is only an example, but there are many scenarios in all industries that this thought process applies to. When the control system is the bottleneck to a part of your process, it is a simple justification to move forward with a migration.


Software/Hardware Manufacturer Support-

Possibly the single most important reason for considering a migration is the support from the manufacturer of the hardware/software. Support for legacy products can be limited, or even non-existent at the end of a platform’s lifecycle. In many cases, technical support is offered after hardware manufacturing ceases, but not for long. At this point, many companies have to settle for paying premium prices for refurbished hardware and legacy control system support from third party vendors. Migrating to the latest technology will enable a quick return on investment just by having quick and easy access to spare parts and highly documented and updated technical support.


Digital Transformation Initiative-

In the era of the Industry 4.0, IIOT, and Digital Transformation, legacy control systems become the first obvious obstacle when constructing a logical path to open architecture connectivity among all of your assets. Legacy control systems with proprietary communication protocols can be connected to an open architecture platform with the assistance of something like an OPC/UA framework, but the use of emerging ethernet technologies will provide an increased amount of capability for data acquisition, scalability, and the ability to mix different application protocols over the same media. With that being said, if your organization is undertaking a Digital Transformation initiative, migrating your legacy equipment is the most efficient course of action.


Final Considerations-

There is no such thing as a typical PLC/HMI migration. Keep in mind that the control systems that you are looking at migrating might be in place for the last thirty or forty years. Be prepared for start-up issues with the new system, and always consider utilizing the knowledge of a systems integrator that has hands-on experience with these types of migrations, if possible. Power, I/O, size, and cooling requirements are some, but not all variables to consider when collecting information for a migration. These variables may or may not be directly compatible with the old and new systems. Developing a strategy to compare and contrast the new and old systems will help eliminate unwanted annoyances during the project. A migration does not have to be a painful process if your team does their due diligence in collecting the proper information needed to mitigate any foreseeable issues.




Industrial Automation Manager


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