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FANUC Alarm SRVO-004 — SERVO Fence open

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-004 (“SERVO Fence open”): On the terminal block TBOP4 of the panel board, no connection is made between 5 (EAS1) and 6 (EAS11) or between 7 (EAS2) and 8 (EAS21). First check: 1. If a safety fence is connected, close the door. Likely part: Panel board (Operator panel board) +1 more.

Updated 2026-10-22 · LogrobotLM reference

Description

On the terminal block TBOP4 of the panel board, no connection is made between 5 (EAS1) and 6 (EAS11) or between 7 (EAS2) and 8 (EAS21). If a safety fence is connected between 5 (EAS1) and 6 (EAS11) or between 7 (EAS2) and 8 (EAS21), the door of the safety fence is open.

Remedy

1. If a safety fence is connected, close the door. 2. Check the switch and cable connected to 5 (EAS1) and 6 (EAS11) or 7 (EAS2) and 8 (EAS21). 3. When this signal is not used, make a connection between 5 (EAS1) and 6 (EAS11) or between 7 (EAS2) and 8 (EAS21). 4. If SRVO-004 (Fence open), SRVO-007 (External emergency stops), SRVO-213 (Fuse Blown (Panel PCB)), and SRVO-280 (SVOFF input) occur simultaneously, it is likely that FUSE1 on the panel board has blown. Check the fuse. If it has blown, remove the cause, then replace the fuse. Else, check the external voltage on EXT24V and EXT0V (TBOP6). If external 24V and 0V is not used check the jumper pins between EXT24V and INT24V, EXT0V and INT 0V (TBOP6). 5. If the problem still exists, replace the panel board.

Field diagnosis

In AUTO mode, the fence circuit connected to the dual inputs EAS1/EAS11 and EAS2/EAS21 is open.

What to check

  • Close the fence door after checking that nobody is inside the cell, then reset.
  • Otherwise check the switches and cables connected to both EAS channels on the emergency stop board terminal block; without a fence, the jumpers must be in place.
  • Note: A single open EAS channel gives SRVO-266/267 (chain), not SRVO-004: the code distinguishes an open door from an out-of-sync channel.

Part to check / replace

FANUC SRVO-004 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

SRVO-205SYSTEM Fence open(SVEMG abnormal)SRVO-266SERVO FENCE1 status abnormalSRVO-267SERVO FENCE2 status abnormalSYST-009WARN Safety Fence openSRVO-002SERVO Teach pendant E-stopSRVO-003SERVO DEADMAN switch released

Same hardware involved

PRIO-093FuseSRVO-008FuseSRVO-212FuseSRVO-213Fuse

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 →