A customer called us after their entire wastewater facility had been down for almost 15 hours. They assumed a recent network change by the IT department was the cause.
Once our technician arrived, the problem was clear: the PLC battery was dead. Combined with a power cycle by a plant technician, that erased the program from memory.
It's a story all too common in industrial controls. We've all gotten that call — an erased program or lost parameters — and wished someone had documented the system, mitigated the risk or simply backed up the program. In this case, a battery that costs next to nothing shut the plant down for two whole shifts.
In the article for Control Design, Preston covers how to prevent it: regular battery maintenance, secure and centralized program backups, and upgrading legacy PLCs to modern controllers with non-volatile memory.
