Maintenance
Your SCADA backup probably does not restore
The most common serious finding on a first maintenance visit is not a missing feature. It is that nobody has ever tested the backup.
Ask a plant whether its control systems are backed up and the answer is almost always yes. Ask when a restore was last performed and the answer is almost always silence.
This is not negligence. Backups get taken by whoever commissioned the system, in a way that made sense at the time, and then the conditions quietly change around them.
The five ways a control system backup fails
- It is on one engineer's laptop, and that laptop has since been reimaged, lost or left with the engineer.
- It exists but has drifted — the standby's project is eleven months behind the primary, so restoring it restores a plant that no longer matches site.
- It restores, but only onto software you no longer have a licence for.
- It covers the SCADA and not the controllers, or the controllers and not the drives. Drive parameters are the most commonly forgotten and among the most painful to reconstruct.
- It has never been tested, so nobody discovers any of the above until the day it matters.
The only test that counts
Restore onto a machine that is not the production machine, and prove the restored project matches site. Anything short of that is a copy of a file, not a backup. If it takes a day, that day is cheaper than the alternative by several orders of magnitude.
What a complete backup set covers
- Controllers
- Program and configuration for every PLC, including remote and distributed I/O configuration
- Operator panels
- HMI projects for every panel, at the version actually running
- SCADA
- Project, tag database, alarm configuration, graphics, scripts, and the redundancy configuration
- Drives
- Parameter sets for every VFD and servo drive — the most commonly missed item on the list
- Network
- Switch configuration, IP schedule and network topology drawing
- Licences
- Licence keys and the software versions needed to open every file above
- Documentation
- As-built drawings, I/O list, functional description, interlock matrix
Getting this right is unglamorous and cheap. It is also the single highest-return day of maintenance work available on most plants, and it is the first thing worth checking on any system you have inherited.
Related services
More
- Retrofit
Planning a PLC changeover around the shutdown window you can actually get
The window is the constraint. Everything else in a retrofit is arranged around it, including the decision to stop.
- Migration
Allen Bradley to Siemens: what actually transfers, and what does not
Cross-brand PLC migration is sold as a conversion and delivered as a rewrite. Here is where the line falls.
Next step
Tell us what the plant is doing
Send the problem, not a specification. An engineer will come back to you — usually the one who would do the work.
An engineer responds within one business day.