What a PLC upgrade can do for you

Improving plant profitability and processes

This is the second white paper in Schneider Electric’s Profiting from PLC Migration series of 3, designed to help manufacturers and municipalities evaluate their need for PLC upgrades and implement them with success.

This paper elaborates on the many ways in which modernization efforts contribute to plant profitability and improve operations. The first paper published in the previous Industrial Marketplace focused on demonstrating ROI in the context of present and future profitability. The third paper, Critical Success Factors in PLC Migration, focuses on the migration process itself, providing a checklist of the key points to consider to achieve the benefits described before launching a
PLC migration venture.


Although some of the first programmable logic controllers installed in the early 1970s are still functioning as designed, many are increasingly vulnerable to failure. Whether they fail tomorrow, next week or five years from now is not an easy thing to predict. The facility that runs with controllers from multiple vendors, spanning multiple generations and of multiple types, further complicates things. With each day of operation, the risk of failure increases and with that comes higher replacement costs, downtime, and upgrade decisions driven by urgency rather than strategy. “Fixing” your controls before they break, however, can have tremendous benefits. Most companies find the control system migrations pay for themselves within two years – with the value coming through immediate improvements & more longer-term ones. These are generally in the following areas:

  • Operational profitability
  • Reduced unplanned downtime risks
  • Improved time to repair
  • Operational improvements
  • Maintenance cost optimization

Operational profitability improvement

Modernizations have historically been perceived as having low ROI, especially when looked at from an “if it ain’t broke, don’t fix it” lens. But today’s technology is changing all of that, with plant stakeholders realizing that much greater ROI and productivity gains can be had by modernizing the existing systems and leveraging the enhanced connectivity therein. Upgrading to a more powerful controller, for example, might raise production value by monitoring quality control variables in real-time or speeding time to market. A controller with improved connectivity might reduce energy costs by enabling real-time monitoring or reduce material costs by improved feed control. We have seen examples of operational profitability improvements in Schneider Electric factories, wherein modernization of PLCs resulted in significant reduction in wastage and rework & improvements in cycle-times.

Reduce unplanned downtime risks

Upgrading from an older generation PLC to a more modern PLC or programmable automation controller (PAC), can significantly reduce the downtime risks to it and the operations it controls. This is a consequence of:

  • Modern technology: The PACs of today inherently take advantage of the latest technological advances and the capabilities they enable. Gone are the days of running the risk of losing critical data or worse – PLCs stopping, due to battery failures. Current PACs no longer use batteries. They are usually also without any moving parts, which used to be another cause of failure.
  • Securing Uptime: In addition to having many more years of productive life in them, modern controllers reduce risk with better diagnostics, connectivity, and visibility, making it increasingly likely that you can fix things before they break. In fact, today they offer predictive diagnostics into one of the most susceptible components of a PLC system i.e. its power supply. This helps in anticipating and avoiding downtime.
  • Cybersecurity: Many an industrial facility security policy is even today based on “security through obscurity.” They believe that their control system and its data, is safe if they are not networked. This is not quite true, however, given that personnel factors, thumb drives and other vulnerabilities can inflict air-gapped systems as well. When these vulnerabilities are exploited, the consequence can be much more severe than a system downtime event. A recent attempt by a hacker in infiltrating and changing a setting of a system controlling a water treatment facility, is a wakeup call to the dangers. Modern PACs are more likely to have cybersecurity at their core, thus being more ready to be setup to defend against such hacks.

Improved time to repair

Support for hardware replacements while the system is online, is par for the course in today’s controllers. While this itself helps improve its time to repair, migrating from older control systems also means:

  • Protection from obsolescence: Once a control system vendor pulls the plug on product support, a key element contributing to repair time – spares availability starts getting affected. In time, the aftermarket comes into the equation, which can improve spares availability. Many suppliers are committed to high standards of quality and customer service, but not all. Questions of quality control, compatibility, and even product counterfeiting enter the picture, which brings new downtime risks.
  • Upgrading to the latest generation system, restores spares availability to normal levels from trusted suppliers, immediately and well into the future.
  • Improved ability to repair: This is about knowing what to repair and how to do so. If you installed PLCs more than 10 years ago, odds are good that many of the people who can program and diagnose them have either left or are looking at the door. Then again, we have also seen quite a few installations of legacy systems, programmed in languages, that is Greek and Latin to newer generation staff tasked to maintain them. This leaves you with a dilemma regarding the value of investing in training new hires on equipment that is nearing the end of its life. The solution is to invest in the modern controllers based on the knowledge they are familiar with, controllers which are more digital-native friendly, all of which greatly helps improve their ability to diagnose & repair.
  • Remote maintenance: Diagnosing, updating and configuring some older PLCs requires going through your facility node by node. New control infrastructures are networked so that diagnostics, configuration and patch management can be done remotely, from a central location, vastly improving the time to repair. Moreover, in the pandemic induced new normal, remote maintenance is often the only option possible. This is something that older systems were never designed for; in addition to the cybersecurity risks this can introduce to them.

Operational Improvements

Control system upgrades are also the time to implement long overdue operational improvements. It is also the chance to prepare the ground for future improvements. Some of the possibilities are:

  • Improving network performance: While inadequately networked PLCs present one barrier to growth and improvement, first-generation networks can also be maxed out as well. When a communication network is first installed, it usually works just fine, but over time, added devices and increased data traffic can lead to sporadic slowdowns or even breakdowns. Networks and their controls must be sized based on realistic node configurations and traffic patterns. Newer PACs have the higher bandwidth and horsepower that may be needed to manage increased traffic.
  • Improved system availability: Many of the older PLCs didn’t have functionality to improve system availability. Today’s PACs support functionality like redundant power supplies, network redundancy, processor redundancy, all of which individually & collectively, contribute to improve system availability. This gives you the flexibility to choose the level of system availability improvement you want to implement, aligned to the criticality of the operations it controls.
  • Improving staff efficiency: Automation, almost by definition, has made it easier for companies to accomplish more with fewer people, but today’s technology is focused as much on empowering individuals and workgroups to make a greater contribution to profitability. Upgraded controllers have the bandwidth and connectivity that can augment operators with more visualization, greater context and the real-time collaboration they need to keep operational profitability on track.
  • Enabling an improvement roadmap: Today’s controllers come with previously unheard of levels of processing power. This opens possibilities of implementing more functions in the new controller, for operational improvements, beyond what was in its predecessor. This is what the team in our factory did, when they modernized their PLCs, resulting in noteworthy gains. What’s more, that after all this, the processing capacity today’s controllers bring ensures that you have enough reserve for handling improvements well into the future too.

Maintenance cost optimization

The control systems in a facility are usually the result of CAPEX purchases, wherein maintenance or lifecycle costs is one among many other decision criteria. On the contrary, control system migration provides you with an opportunity to set things right, with more emphasis on lifecycle costs. Some of the things that can help in optimizing maintenance cost are:

  • Open technologies: Today’s PACs, have moved away from proprietary blue hoses and purple cables, and are now based on open technologies like ethernet. This can have a big impact on system maintenance costs, to name a few – reduced dependency on single-source procurement, wider resource pool, no need to maintain dedicated workstation etc. When a steel plant was struggling to maintain an old dedicated system, they had a choice to upgrade to the latest proprietary offering or to move to an open one. They chose the latter, which not only meant lower project costs, but also resulted in significant lifecycle savings.
  • Inventory rationalization: Invariably, you end up with a facility, having a high diversity of systems, be it from multiple vendors or multiple types of systems from the same vendor or multiple types of systems itself. All this results in is a high level of spare inventory, rationalizing of which can result in savings. Having this as an objective when you consider modernizing your control systems, will help you choose platforms that can help you achieve this. Eventually, this will result in a much more homogenous set of spares, to reduce costs and simplify maintenance.
  • Engineering Software rationalization: Too often, a high diversity of systems, also results in an equally heterogenous mix of engineering software in your facility. Apart from the strain it places on available skills, it also increases software maintenance costs. In addition, some of these would be compatible to older versions of Microsoft Windows, needing dedicated workstations / laptops, which apart from costs, also adds to cybersecurity risks & IT scrutiny. As you go about modernizing your facility, you could not only eliminate some of the older software, but also look at optimizing the engineering licenses in the facility, leading to maintenance cost savings.
  • Support simplification: While inventory rationalization can help you realize standardization benefits within control systems, there could also be opportunities for further savings beyond it. This could be from simple things like reducing the number of support contacts to gaining scale benefits by consolidating support.

Industrial Internet of Things (IIoT)

Thirty to forty years ago, the proliferation of automation advanced industrial productivity by bringing devices such as relays, instrumentation, and valves under computer control. We are now experiencing the next level of industrial efficiency, which is characterized by heightened connectivity — not only among traditional automation components, but also among industrial devices and applications — i.e. the IIoT. Migration to modern controllers to deliver most of the benefits discussed thus far will also likely have the capability to exploit the full capability of the IIoT. Schneider Electric’s Modicon PAC platforms for example, have the following features that will help deliver on many of the objectives mentioned above:

  • Based on state-of-the-art technologies resulting in a step change in system performance, improved availability and better connectivity without letting you compromise on cybersecurity.
  • One common & consistent IO platform, from small to large applications in your facility.
  • Seamless integration into our open & interoperable IIOT ready EcoStruxure Plant architecture.

A pragmatic approach to building a roadmap for PLC modernization

In our experience, time and again, the following approach, balancing a macro-level view with a micro one, has helped many of our customers taste success in their PLC migration projects:

  • Establish a baseline: This is the starting point, where the objective is the identification of any obsolescence risks prevalent in the different PLC systems. Obsolescence risks even today are one of the main drivers for PLC migration. Look for credible inputs that can help you plan & prioritize better – current lifecycle state of all modules making up the system, its evolution over the next few years and its implications. Here, it’s a good practice, to do an annual refresh of this data, to avoid any surprises in subsequent years.
  • Identify priorities & vision: Conduct a workshop with all relevant stakeholders i.e. operations, engineering, maintenance, IT & management. Objective here is to determine what the end-state of your operations should look like. Inputs here are things like – business drivers, operational objectives, current challenges etc. This will help in defining the overall expectations from a PLC migration. Knowing the overall expectations and its significance, helps in finding options aligned with it.
  • Explore options: Seek information about the possible platforms to migrate your existing PLC systems to. Look for functionality that can deliver the expected improvements and thus take your operations
    closer to the desired end state. Here, in addition to what’s available currently, knowing product roadmaps can help you to benefit from possible technological evolutions and avoid surprises.
    Develop overall plans: Based on all the above inputs and with the knowledge of your facility shutdown schedules, you should now be able to arrive at a high level overall migration plan. A roadmap that can provide answers to what PLC to modernize when and to what, resulting in what operational improvement.
  • Refine plans: At this point, we have largely taken an approach centered around operational improvements, to arrive at the overall migration plan. This may need refinement based on – your ability to maintain the existing system till its scheduled upgrade & overall implementation time for the migration project. A critical system with little or no maintenance spares, for example, may need to be prioritized for an earlier upgrade. At the same time, a full replacement might not fit within your turnaround schedule. All this could result in you taking a stepwise approach, creating a long-term end game for the migration, but working toward it in manageable chunks, usually during scheduled turnarounds.


So, whether your concerns are at the unit, area, division or enterprise level, upgrading to modern PACs could help you address today’s maintenance, production or operational challenges, while equipping you for the newer & emerging opportunities of tomorrow. To do so, start with establishing
a baseline of all the different systems in the facility, leading to a holistic planning exercise with all relevant stakeholders, that results in a modernization roadmap, aligned to your operational priorities & shutdown schedules.

For more details on how PLC migration can drive profitability improvement, see the third paper in the next magazine, “Critical Success Factors in PLC Migration”.