FAL 9F Omron — Memory error / backup battery depleted
At a glance
- Severity
- WARNING
- Domain
- PLC
- Reference standard
- IEC 61131-2
- Product / context
- Battery Error — CJ2M
What it means
The CPU reports a retentive memory or backup battery error. On battery-equipped CPUs (older series), the BAT/BATF LED is flashing or solid. On newer CPUs with flash memory, the error indicates non-volatile memory corruption. Retentive data (counters, recipes, operating hours) are at risk of being lost at the next power-off.
Probable causes
- Lithium backup battery exhausted after 5-10 years of service.
- Memory card with damaged sectors or corrupted by power interruption during write.
- Excessive write cycles on flash memory (intensive data logging on memory card).
- Ambient temperature out of range reducing battery and memory life.
Where to start
Does the CPU have a BAT/BATF LED lit or flashing? (Note: Siemens S7-1500 CPUs and recent CPUs do not use batteries -- skip to the next step if not applicable.)
Full guided diagnosis in the app
The diagnostic tree for this fault has 7 guided steps with measurements, checks and resolutions. You'll find it in ElectraIQ, one of the four IndexOS apps: free, works offline.
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The same fault on other brands
More Omron codes
- FAL C0 — CPU ↔ I/O module communication error (backplane bus)
- NX-AD4608 — Analog input module — full-scale reading or error
- NX-ID5442 — Digital input module — input not reading (stuck at 0)
- NX-OD5256 — Digital output module — output not activating
- NX-SID800 Fault — Safety module F-CPU/F-DI/F-DO in passivation
- S8VK-G12024 — Unstable PLC power supply — cyclic restarts