What the SRVO-235 alarm means

A momentary mismatch was detected in the E-stop chain - the fault appeared and disappeared within a short time window. This is one of the most common faults in our repair logs for the FANUC R-30iA / R-30iB / R-30iB Plus platform, and the first inspection typically locates the cause.

Most common causes

  • Loose or oxidized connector making intermittent contact (vibration)
  • Worn E-stop or door switch contacts bouncing
  • Cable damage that only opens at certain robot positions
Field note: Field experience says the first cause is the most likely — verify it before moving on to the rest.

Step-by-step field fix

  1. Wiggle-test all safety circuit connectors while monitoring the chain status
  2. Flex suspect cables through their full motion range
  3. Replace marginal switches - intermittent faults always get worse
  4. Check cable carrier runs for fatigue breaks
Safety first: For FANUC srvo-235, this alarm is the safety circuit itself: jumpering a door switch or forcing a contactor removes the protection entirely - no protective action when something happens, and no defensible account of responsibility. On site you may look at after confirming power-off the first step yourself: Wiggle-test all safety circuit connectors while monitoring the chain status. Beyond that it is the e-stop chain and safety circuit work - leave it to a professional.

How we diagnose safety-chain faults on site

FANUC srvo-235 belongs to the safety chain & e-stop family. On FANUC srvo-235 the failing stage is Dual Check Safety (e-stop board plus dual-channel safety circuit) on the R-30iB Plus / R-30iB Mate Plus / R-30iA - continuity of one series loop: e-stop buttons, door switches, light curtains, safety relays and the enabling device. We start reading FANUC srvo-235 at the iPendant ALARM screen (SRVO / MOTN / SYST / INTF prefixes) together with the amplifier's 7-segment status code.

The chain involved in FANUC srvo-235 runs: e-stop / door / curtain -> safety relay (dual channel) -> controller safety input -> motor-off and brake apply.

On FANUC srvo-235 (field clue usually Loose or oxidized connector making intermittent contact (vibration)) we have one hard rule: On this family we have a hard rule: no bypassing the safety loop, no forcing contactors closed, ever. Some sites jumper the door switch to keep running - that removes the entire protection function, and when something happens there is no protective action and no defensible account of responsibility. We have seen a crush injury caused by exactly that jumper, so we would rather wait for parts than do it. If a customer has already jumpered it, we restore the circuit first and then diagnose the real fault.

Field notes on this page cover FANUC srvo-235 (Short-Term Chain Abnormal); written by the Henghuan repair team, updated 2026-10-01.

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Related Safety Chain & E-Stop alarms

SRVO-105 — Door Open or E.Stop SRVO-201 — Panel E-Stop SRVO-202 — TP E-Stop SRVO-204 — External E-Stop (SVEMG Abnormal) SRVO-230 — Chain 1 (+24V) Abnormal SRVO-231 — Chain 2 (0V) Abnormal
Same family: this code belongs to the Safety chain & e-stop alarms family - the page collects all Safety chain & e-stop-family codes we have handled, with the common inspection order and spares.
Other brands: see our KUKA, ABB, Yaskawa and Universal Robots field-fix libraries — or the full 10-brand hub.

Frequently asked questions

QWhat does the FANUC srvo-235 alarm mean?

A momentary mismatch was detected in the E-stop chain - the fault appeared and disappeared within a short time window. This is one of the most common faults in our repair logs for the FANUC R-30iA / R-30iB / R-30iB Plus platform, and the first inspection typically locates the cause. FANUC srvo-235 sits in the safety chain & e-stop family; on our work orders the highest-frequency trigger for this code is "Loose or oxidized connector making intermittent contact (vibration)".

QCan I clear a FANUC srvo-235 alarm myself?

Whether FANUC srvo-235 clears on its own depends on the outcome of "Wiggle-test all safety circuit connectors while monitoring the chain status". Finish the flow with "Check cable carrier runs for fatigue breaks" to confirm FANUC srvo-235 - do not skip it. If that step is clean, the second most frequent cause on FANUC srvo-235 is "Worn E-stop or door switch contacts bouncing". If FANUC srvo-235 returns after two clears, or the checks point at Loose or oxidized connector making intermittent contact (vibration), stop the cell and call a professional robot repair engineer.

QA safety-chain fault like FANUC srvo-235 stops the line - how fast can you be here?

The commonest causes we see on FANUC srvo-235 are "Loose or oxidized connector making intermittent contact (vibration), Worn E-stop or door switch contacts bouncing, Cable damage that only opens at certain robot positions", so we stock the van against those. For FANUC srvo-235 specifically, we stock along the loop: safety relays, common door switches, e-stop buttons, light-curtain pairs and terminal blocks. For FANUC srvo-235, a safety-chain fault stops the whole line, so we rank it top priority and pre-triage by phone: door switch, e-stop or relay. Before we roll, tell us what FANUC srvo-235 shows on the iPendant ALARM screen (SRVO / MOTN / SYST / INTF prefixes) together with the amplifier's 7-segment status code and what the machine was doing - phone or video triage is free.

The notes on FANUC srvo-235 were summarized by the Henghuan Robotics repair team from on-site service. The alarm interpretation is our empirical summary for troubleshooting reference and may vary by controller and software version — please check FANUC documentation or contact us with questions. Henghuan is an independent service provider, not affiliated with or endorsed by FANUC.