What to Do Before an Automation Component Becomes an Emergency

Legacy PLCs and automation components can become difficult to source when manufacturers discontinue production. Early identification and procurement planning can help industrial facilities reduce unexpected downtime.

Full Blog Content

Industrial automation systems are often designed to operate for many years. However, the lifecycle of individual automation components is not always the same as the lifecycle of the machine.

A PLC installed years ago may continue to control an important production line even after the manufacturer has stopped producing that specific model.

This creates a major procurement and maintenance challenge:

What happens when the PLC fails and the original replacement is no longer readily available?

This is the problem of PLC obsolescence.

What Is PLC Obsolescence?

PLC obsolescence occurs when a programmable logic controller or related automation component reaches the end of its commercial lifecycle.

The manufacturer may:

• Stop manufacturing the model
• Stop accepting new orders
• Reduce technical support
• Discontinue spare parts
• Replace the model with a newer generation

For an industrial facility, this does not necessarily mean the existing system immediately becomes unusable.

However, sourcing replacement components can become increasingly difficult.

Why Is PLC Obsolescence a Procurement Risk?

Production facilities depend on automation systems for critical operations.

A failed PLC module, communication module, power supply, I/O module, or processor can stop an entire process.

If the component is obsolete, procurement teams may suddenly face:

• Limited supplier availability
• Longer lead times
• Higher prices
• Alternative part compatibility issues
• Used or refurbished component requirements
• Difficult technical verification

Waiting until the component fails can therefore turn a normal maintenance requirement into an emergency procurement situation.

Identify Critical Automation Components Early

A practical approach is to maintain an inventory of critical automation components.

Record information such as:

• Manufacturer
• PLC family
• CPU/processor model
• I/O module numbers
• Communication modules
• Power supply model
• Firmware requirements
• Existing quantity
• Installed quantity
• Recommended spare quantity

This information allows procurement and maintenance teams to identify vulnerable components before a failure occurs.

Original Replacement vs Alternative Solution

When an automation component becomes difficult to source, there may be several possible approaches.

Original Component

The original part is generally the simplest option when it remains available and technically suitable.

Equivalent Component

An equivalent component may be considered when the original model is unavailable.

However, compatibility must be carefully checked.

Important considerations include:

• Electrical compatibility
• Communication protocol
• I/O configuration
• Software compatibility
• Firmware
• Mounting
• Power requirements
• Existing PLC architecture

Modernization

In some cases, replacing an obsolete PLC platform with a newer generation may be more practical.

However, modernization requires engineering planning and should not be treated as a simple component replacement.

Build an Automation Spare Strategy

A good procurement strategy combines technical information with purchasing planning.

Critical spare components can be categorized as:

Critical: Failure immediately affects production.

Important: Failure reduces operational capacity.

Standard: Replacement can be planned without immediate production impact.

This classification helps determine which components should be kept in stock and which can be sourced when required.

What Information Should You Send When Sourcing a PLC?

When requesting an automation component, provide as much information as possible:

• Manufacturer
• Complete part number
• Model number
• Series
• Photograph
• Existing application
• Quantity required
• Required delivery timeline
• Existing PLC platform
• Any available datasheet

A photograph of the installed component can also help identify the correct product.

Final Takeaway

PLC obsolescence becomes a serious problem when it is discovered after a production failure.

Maintenance and procurement teams can reduce this risk by identifying critical automation components, monitoring their lifecycle, maintaining essential spares, and planning alternatives before an emergency occurs.

Supply Link Solutions supports industrial procurement requirements for automation, electrical, instrumentation, process control, and other industrial spare parts.