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FANUC Alarm SRVO-235 — SERVO Short term Chain 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-235 (“SERVO Short term Chain abnormal”): A chain failure alarm is detected in short term. First check: If this error occurs with a deadman switch release alarm, release the deadman switch again and press the deadman switch.

Updated 2026-10-22 · LogrobotLM reference

Description

A chain failure alarm is detected in short term.

Remedy

If this error occurs with a deadman switch release alarm, release the deadman switch again and press the deadman switch. Or, if this error occurs with another safety signal error,

Field diagnosis

Only one channel of the chain switched briefly: deadman switch half released or emergency stop button pressed halfway.

What to check

  • Deliberately reproduce the fault (press fully, then release), wait for SRVO-236, reset.
  • If the phenomenon repeats without anyone handling anything, replace the emergency stop board, then the servo amplifier.
  • Note: Most often an operator action, not a failure; it becomes a failure when it occurs with the robot idle.

Related codes

SRVO-230SERVO Chain 1 (+24v) abnormalSRVO-231SERVO Chain 2 (0v) abnormalSRVO-003SERVO DEADMAN switch releasedSRVO-233SERVO TP OFF in T1,T2/Door openSRVO-234WARN Deadman switch releasedSRVO-236WARN Chain failure is repaired

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 →