FANUC Alarm SRVO-266 — SERVO FENCE1 status abnormal
Error- Hardware
- emergency stop and dual safety chains
- Controllers
- R-J3iB / R-30iA / R-30iB
- FANUC class
- SERVO
- Hardware family
- FANUC emergency stop, pendant and dual safety chain alarms
FANUC SRVO-266 (“SERVO FENCE1 status abnormal”): The FENCE2 status is still ON when the FENCE signal is asserted. First check: Repair the FENCE2 circuit.
Updated 2026-10-22 · LogrobotLM reference
Description
The FENCE2 status is still ON when the FENCE signal is asserted.
Remedy
Repair the FENCE2 circuit.
Field diagnosis
Chain alarm on the fence signal: channel 1 does not follow channel 2, typically incorrect EAS wiring or a contact that switches late.
What to check
- Check the circuit connected to both EAS inputs and that simultaneity between channels is respected.
- After repair, release the chain condition: press then release an emergency stop, RES_1CH on the active alarm screen, then RESET.
- Note: One dead channel with the other healthy lets the robot keep running: do not reset without having repaired it.
- Diagnostic sequence “Dual emergency stop circuit”: A chain code (230/231, 266…275, 370…373) means that only one of the two redundant channels has switched: the robot still runs, but safety is no longer redundant. Identify the channel from the number (1 = +24 V, 2 = 0 V), reproduce a firm operation of the device concerned, wait for the chain-repaired message, then RES_1CH and RESET. Never reset without having found the cause.
Related codes
Indicative field information — the robot manufacturer's manual and safety procedures always prevail. Never bypass a safety device; apply lockout/tagout (LOTO) before any physical intervention. How this reference is built →