Do we need to replace everything at once?

No. Many upgrades can be phased or staged to reduce risk and capital spend.

Which PLC brands do you support?

We specialise in Siemens, Allen Bradley, and Mitsubishi, but also work with other platforms where required.

Can obsolete systems be upgraded without downtime?

Yes, many upgrades can be planned and executed in stages to minimise or avoid downtime.

When should an obsolete automation system be replaced?

An obsolete automation system should be considered for replacement when spare parts are difficult to source, support is limited, faults are increasing, or the system creates unacceptable downtime and production risk.

Can obsolete PLC systems be upgraded without replacing everything?

Yes. Many obsolete PLC systems can be upgraded through a planned migration, retaining suitable field devices and control panels where appropriate while replacing unsupported hardware and software.

What are the risks of keeping obsolete control systems?

The main risks include longer downtime, limited technical support, difficulty sourcing replacement parts, reduced system visibility, increased maintenance pressure and higher risk of production disruption.

How can manufacturers reduce disruption during an upgrade?

Manufacturers can reduce disruption by planning the upgrade carefully, assessing the existing system, preparing replacement hardware and software, testing before installation and scheduling work around production requirements.

Replace Obsolete PLC and SCADA Systems

Fault finding in a system that has become obsolete

Obsolete PLC and SCADA systems present growing risks to production, safety, and compliance. As manufacturer support disappears and sourcing obsolete parts becomes problematic, even minor failures can lead to extended downtime.

Stratos Control Systems and our engineers specialise in planned PLC and SCADA replacement projects that minimise risk, disruption, and unplanned stoppages while modernising long-term system reliability.

Why Obsolete Control Systems Create Risk

Legacy control systems were not designed to operate indefinitely. Over time, they introduce increasing operational and business risk, particularly when knowledge is lost or systems are modified without documentation.

Replacing these systems requires careful planning to avoid introducing new failures.

Risks of Legacy PLC and SCADA Systems

No manufacturer support or spare parts
Increased failure rates and unpredictable faults
Loss of system knowledge when engineers leave
Cybersecurity and regulatory compliance risks
Difficulty integrating with modern systems

Our PLC and SCADA Upgrade Approach

We manage PLC and SCADA upgrades using a structured migration process:

Full audit of existing PLC, HMI, and SCADA systems
Migration planning using Siemens, Allen-Bradley, or Mitsubishi platforms
Parallel testing to validate functionality before cutover
Staged commissioning to minimise downtime
Clear documentation and operator training

Why Planned Replacement Works Better

A planned replacement avoids emergency shutdowns, rushed installations, and undocumented fixes.

It also creates a platform that is easier to maintain, safer to operate, and supported long term.

What Obsolete Legacy Systems Look Like in Practice

Obsolete systems rarely fail all at once. They create ongoing risk across PLCs, control panels, and software, where outdated hardware, unsupported components, and limited integration make faults harder to resolve and increase the likelihood of unplanned downtime.

How to deal with Obsolete Industrial Systems

Download the Guide on How to Update Obsolete Systems

Obsolete systems rarely break overnight. They gradually impact performance across your infrastructure, increasing downtime, raising maintenance costs, and limiting your ability to scale or integrate with modern automation.

Download the Guide

Improve Visibility and Long-Term Supportability

Modern control systems improve visibility, diagnostics, and maintainability.

Replacing obsolete PLC and SCADA systems enables:

Clear system visibility and monitoring
Improved diagnostics and alarm handling
Better integration with modern platforms
Long-term vendor support and scalability

Who This Is For

This approach is typically used by:

Engineering Managers managing ageing control systems
Maintenance Managers dealing with obsolete PLC hardware
Operations teams experiencing increased downtime risk
Businesses planning phased system modernisation

Speak to an Automation Engineer

Siemens control panel for PLC upgrade project.

Frequently Asked Questions

Plan a control system upgrade

Replace obsolete PLC and SCADA systems safely with minimal disruption.