FANUC Alarm SRVO-348 — DCS MCC OFF alarm …,…
Error- Hardware
- main contactor (MCC)
- Controllers
- R-30iA / R-30iB
- FANUC class
- SERVO
- Hardware family
- FANUC DCS, main contactor and safety input alarms
Manufacturer wording — DCS MCC OFF alarm %x,%x
The manual prints placeholders; your controller fills them in with the real group, axis or number.
FANUC SRVO-348 (“DCS MCC OFF alarm …,…”): A command was issued to turn off the magnetic contactor, but the magnetic contactor was not turned off. First check: 1. Replace the E-stop unit. Likely part: E-stop unit (E-stop unit) +1 more.
Updated 2026-10-22 · LogrobotLM reference
Description
A command was issued to turn off the magnetic contactor, but the magnetic contactor was not turned off.
Remedy
1. Replace the E-stop unit. 2. Replace the panel board. 3. If a signal is connected to the emergency stop unit CRM72, check whether there is a problem in the connection destination.
Field diagnosis
Open command sent to the main contactor, but the contactor has remained closed.
What to check
- If a signal is connected to the emergency stop unit connector (CRM72/CRMB8 depending on generation), check the connected device; check the seating of the signal connector on the amplifier; replace the emergency stop unit (contactor included), then the panel board/main board.
- Note: Welded contactor contacts: the robot can no longer be put in a safe state; to be dealt with as an absolute priority.
Part to check / replace
FANUC SRVO-348 points to the hardware below — start here before ordering.
Tap a part for every code that points to it — and verify the exact variant for your controller before ordering.
Related codes
Same hardware involved
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 →