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Signals and PLC · Glossary

What is PLC Redundancy?

hot standbySignals and PLC

PLC redundancy uses duplicate controllers, power supplies or networks so the system keeps running if one part fails.

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PLC Redundancy Explained

In hot standby, a backup CPU tracks the primary and takes over bumplessly on failure. Redundant power supplies, I/O and networks remove other single points of failure.

Redundancy must be tested, and both units kept at the same firmware and program.

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Calculators for PLC Redundancy

CalculatorAvailability CalculatorFree online calculator with formula and worked example.CalculatorMTBF CalculatorFree online calculator with formula and worked example.

Frequently Asked Questions

What is PLC Redundancy?

PLC redundancy uses duplicate controllers, power supplies or networks so the system keeps running if one part fails.

Is redundancy the same as safety?

No. Redundancy improves availability; safety systems need certified design under IEC 61508 or 61511.

What is switchover time?

The time the backup needs to take control; outputs should hold during it.

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PLC redundancy and hot standby

A practical guide on instrumentationblog.in with more detail on PLC redundancy and how it is applied on real plants.

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