FANUC Alarm SRVO-250 — SERVO SVEMG/MAINON1 abnormal
Error- Hardware
- emergency stop and dual safety chains
- Controllers
- R-J3iB / R-30iA
- FANUC class
- SERVO
- Hardware family
- FANUC emergency stop, pendant and dual safety chain alarms
FANUC SRVO-250 (“SERVO SVEMG/MAINON1 abnormal”): Status of MAINON1 signal is still OFF even if SVEMG is ON It is abnormal of E.STOP First check: Repair the circuit of E.Stop hardware Power off/on again
Updated 2026-10-22 · LogrobotLM reference
Description
Status of MAINON1 signal is still OFF even if SVEMG is ON It is abnormal of E.STOP
Remedy
Repair the circuit of E.Stop hardware Power off/on again
Field diagnosis
The SVEMG signal is active but MAINON1 stays inactive: the emergency stop circuit does not report the expected state.
What to check
- Repair the emergency stop circuit (E-stop unit connectors, relays), then switch the mains power off and back on to clear.
- Note: Code from the R-J3iB/R-30iA generation; on R-30iB, the same family of fault appears as SRVO-348/349.
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 →