Control System Upgrade Part 1: Understanding When It’s Needed

Upgrading a control system is a complex process that requires careful analysis of the equipment to which it’s connected. While mechanical equipment upgrades can result in more tangible benefits (increased throughput, efficiency, etc.), the improvements resulting from a controls upgrade are more nuanced.

In general, a well-executed controls upgrade creates a safer, more reliable system with less downtime, better access to spare components, and the potential for savings on utilities. However, because the controller is the central hub of the system, the project needs to be approached in a thoughtful manner, with strong knowledge of the interfacing equipment, the protocols used for communication between them, and the programming methodologies used by both the old and new PLCs.

In this article, part of a two-part series, we’ll explore scenarios where a control system upgrade is necessary. Depending on the specific circumstances, one or several of these factors may be valid concerns driving the decision.

1. It’s Difficult to Obtain Replacement Parts

As a control system ages, it can become progressively more challenging to obtain the necessary spare parts needed to keep it in operation. If the older system was designed with custom parts, custom IC components, or relies on older communication protocols, any of these may become obsolete over time, making support for the system challenging.

Common parts that can be difficult to source for a legacy system include:

• Microprocessors
• Input and/or output cards
• Batteries
• Servos
• Variable frequency drives (VFDs)

2. There Are Compatibility Issues

A control system upgrade may be needed to support newer software platforms and/or equipment that isn’t backwards compatible.

Sometimes, a supporting reason for a controls upgrade is to have the ability to run newer software, such as Siemens TIA Portal, and access its benefits.

Older control systems like Simatic Manager Step 7 Classic do not necessarily have the hardware to support TIA Portal. Their processors may be insufficient, or, likewise, there may be insufficient memory within the computer. TIA Portal requires a means of high-speed communication, of which some older controllers may not be capable. In addition, older HMIs may not meet the requirements needed to run TIA Portal.

Additionally, supply chain problems that occurred alongside the COVID-19 pandemic, forced some controls manufacturers to switch sources for their integrated circuit components. For example, Siemens opted to redesign their TP1500 entire panel (inside and out). Therefore, a TP1500 purchased today as a spare part may not be directly compatible with older versions of the same model.

3. Downtime Issues Have Increased

As equipment gets older, the risk of failures increases. The environment in which the system is operating plays a substantial role in the system’s lifespan, with higher humidity and higher temperature environments presenting a larger strain on the operating components.

Some failure examples include:

VFD – Burning/Overheating Damage

A VFD is composed of power semiconductors in both its rectifier and inverter stages that perform the regular switching operations defining its function. Over time, these components deteriorate, become more resistive and less efficient, increasing energy dissipation as heat. Harsher electrical environments can also contribute to component wear and damage over time.

Relay Output Card Failures/Contact Wear Damage

A relay is a switching device at its core. Over time, the mechanical contacts of the device may become damaged, leading to poor, unreliable connections.

Intermittent component failures are an additional problem with older control systems, resulting in downtime.

4. There Are Cycle Time Gains

A newer control system will likely have a much faster overall processing speed. As a result, the time it takes to receive and interpret inputs, and then drive the resulting outputs, will be much less than that of a legacy device.

5. You Desire Brand Standardization

Streamlining to one particular brand of control system components, for example, Siemens, simplifies support and maintenance, staff training, resulting in less overall monetary investment.

6. The System Is a Security and Safety Risk

Today, two particular technology areas commonly driving the need to upgrade a control system include improved cybersecurity and safety optimization.

Cybersecurity

Depending on the system’s age, there may be limited means of meeting cybersecurity protection requirements. While an old system may have no network connectivity at all (and, therefore, no cybersecurity risk), some more recent systems may be connected to the OT network with limited means of addressing cybersecurity concerns. This limitation can leave more than just the particular device vulnerable to a cybersecurity attack; it effectively leaves an open door for a threat to find its way to several, or possibly all, networked devices.

Safety Standards

It’s important to note that safety standards within manufacturing have been continuously evolving in recent years. A system deemed “safe” as recently as 2005 would likely be deemed unacceptable by today’s standards. In the United States, it is the owner of the manufacturing facility who is responsible, and ultimately liable, for site safety.

As systems are upgraded, a safety risk assessment must be completed. While upgrading to meet today’s safety standards is not a strict legal requirement, failure to meet the standard leaves a manufacturer open to liability and fines should an incident occur. Ensuring equipment meets safety standards proves that a manufacturer has done their due diligence in creating a safe work environment, serving as some legal protection should someone be injured.

A control system upgrade may be required to meet today’s more stringent safety standards. Older control systems have very limited safety control capabilities, while newer systems have more integrated means of including robust safety features in a production line. This is an important requirement when completing a required safety risk assessment and selecting devices that are safe, will fail safe, or are configurable such that a single point of failure will not cause a human hazard or injury. This topic is discussed further in our recent eBook, Common Considerations Integrating Robotics in Manufacturing.

7. You Want to Switch to Servo

In the past, servo control systems were costly to purchase, integrate, and operate. Today, servo systems are far more competitive in price, and newer PLCs incorporate better means of connecting servo systems than their older counterparts. Newer PLCs also support the high-speed communication protocols needed for more precise control and performance, and feature built-in motion control and functionality.

Depending on the application, an upgrade from a hydraulic or pneumatic system to a servo system may improve energy efficiency and reduce overall electricity expenses. In addition, the possibility of costly air leaks (pneumatics) and installation of flow meters to monitor for them is removed. A move away from hydraulics also eliminates the possibility of leaking oil concerns and the potential for explosion in environments that include flammable substances.

8. You Need Software Functionality Improvements

Upgrading to a newer control system allows you to operate your facility using the most up-to-date, integrated software systems, improving code efficiency, downtime recovery, and data connectivity (Industry 4.0). You can read Part Two of this blog series to learn more about software.

When to Replace Outdated Equipment Versus the Controller

There are times when it’s a better decision to fully replace outdated equipment rather than try to update the controller, including:

• The cost of the upgrade is 50% or more of a new unit: Upgrading controls is likely a lesser and short-term monetary investment compared to a full equipment replacement. On the other hand, the latter option comes with a longer lifespan for all system parts.
• The entire system is in poor condition: If the mechanical portion of the system is in generally good condition, a controls upgrade may be the best approach that balances project cost with benefit. On the other hand, if the physical portion of the system is in poor condition, investing in a full replacement could offer the best return on investment.
• You’re okay with waiting: It’s not uncommon for equipment to have a six-month lead time, a timeframe that may be longer than that of an upgrade. You may want to consider a replacement if lead time isn’t an issue, and a replacement seems like the better option based on the conditions listed above.

You’ve Decided to Upgrade—What’s Next?

If upgrading your control system is a better approach for you rather than a replacement, we recommend reading our next blog in this series, Control System Upgrade Part 2: Planning for the Upgrade, which discusses the preparatory steps required for a control system upgrade.

FAQs

What Are the Benefits of Upgrading Control Systems?

Upgrading outdated control systems improves safety and system reliability, reduces downtime, lowers energy costs, and enhances maintenance ease.

What Parts Are Often Hard to Replace in Older Systems?

Microprocessors, input cards, output cards, batteries, servos, and VFDs can be challenging to source and replace for older control systems.

What Can Increase Failure in a Control System?

The environment in which the control system operates in is a significant factor. High humidity and temperature cause more strain on the system, leading to reduced performance and a shorter lifespan.

What Are Current Safety Standards Pertaining to Control Systems?

Safety standards vary on industry. The most common safety standard is IEC 62433, which covers security requirements for industrial automation and control systems, IEC 61508, which discusses functional safety of electrical safety-related systems, and ISO 27001 for IT/OT system convergence. We recommend performing a risk assessment to help determine which hazards need to be mitigated. You can read our eBook for further guidance.

Is Replacing Better Than Upgrading?

Not necessarily. It depends on your situation. We recommend replacing your entire system when it’s in poor condition, the cost of the upgrade is 50% more than a new unit, and if timeline isn’t an issue, because replacements generally take longer than upgrades.