Learn Automation with MINATA #54: Backing Up a PLC Program — A Backup Is Worth What It Can Restore

Backing Up a PLC Program: A Backup Is Worth What It Can Restore

A PLC program backup is worth exactly what it can restore on the day you need it. Plenty of factories believe they have a backup, right up to the morning the PLC fails and they discover the only file lives on the laptop of somebody who left the company — or that it will not open in the version of software they have.

Store it centrally, with access control

Never let a file on a personal machine be the only copy. Keep it somewhere central, with access control and its own backup, so more than one authorised person can reach it when it is needed. The copy on a technician's laptop is a working copy, not the factory's official one.

Naming, and what a backup set contains

Name it with the machine code, the version, the date, who changed it and why. A complete backup set usually holds:

The source project for the PLC and the HMI — the editable files.
The compiled or transfer file, where the device needs it to be reloaded.
Device parameters: exported drive and servo parameters, and the communication configuration.
Related documents: the I/O list, the changelog and the drawings of the matching version.

Keeping only the compiled file means losing the ability to edit. Keeping the source but not the drive parameters means a restoration that is incomplete.

Test the restore, periodically

A backup that has never been restored is an assumption, not a guarantee. Periodically open the file in the correct version of the software, and where circumstances allow, load it into a spare device to confirm the restore procedure actually works. Record the software and firmware versions needed to open it.

A worked engineering situation

After commissioning, the team saves the PLC and HMI projects, exports the drive parameters, and adds the I/O list and the changelog into one handover set. That set is opened again on a different computer, to confirm the version is right and nothing is missing, then stored centrally under a clear naming convention. When the PLC has to be replaced years later, somebody else can restore it without hunting down the original engineer.

The convention, the storage location and the test interval all follow the organisation's policy and the requirements of the equipment.

Common mistakes

Keeping the only file on a personal laptop, with nothing stored centrally.
Names without a version or date, so nobody knows which copy is current.
Saving only the compiled file, and losing the ability to edit.
Skipping the drive parameter export, so a restore is incomplete.
Never opening or restoring it, so nobody knows whether it works.

PLC backup checklist

[ ] Stored centrally, with access control and its own backup.
[ ] The name carries machine code, version, date, person and reason.
[ ] The set holds source, compiled files, parameters and documents.
[ ] The software and firmware versions needed to open it are recorded.
[ ] It is opened or restored periodically to confirm it works.

A backup you can restore is real insurance for the line. #55 turns to HMI alarm design, where a good alarm has to lead to an action.

Read more automation knowledge at MINATA: https://minatavn.com/en/blog/industrial-automation

Previous — #53: Preventive maintenance: https://minatavn.com/en/blog/automation-53-preventive-maintenance

Next — #55: HMI alarm design: https://minatavn.com/en/blog/automation-55-hmi-alarm-design

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