FANUC Alarm SRVO-231 — SERVO Chain 2 (0v) 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-231 (“SERVO Chain 2 (0v) abnormal”): A single chain 2 (0V) failure occurred. First check: 1. Repair the circuit of the chain 2 (0V) on the hardware.
Updated 2026-10-22 · LogrobotLM reference
Description
A single chain 2 (0V) failure occurred.
Remedy
1. Repair the circuit of the chain 2 (0V) on the hardware. 2. Set CHAIN FAILURE detection to TRUE on the SYSTEM/CONFIG screen. 3. Push RESET on the teach pendant.
Field diagnosis
Fault detected on chain 2 of the dual emergency stop circuit: the two redundant signals no longer match.
What to check
- Same procedure as SRVO-230: alarm history, full operation of the device involved, wait for SRVO-236, reset.
- Then check the teach pendant specification and the wiring of the devices on both channels.
- Note: Chain 1 and chain 2 are diagnosed together; a single code out of the two points to the faulty channel.
- 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 →