What the SRVO-280 alarm means

The SVOFF (servo off) input signal is active - an external device is requesting servo power off. In our FANUC service archive this alarm on R-30iA / R-30iB / R-30iB Plus systems shows up constantly, and the first on-site inspection almost always locates it.

Most common causes

  • External servo-off device active (PLC, safety device)
  • SVOFF wiring fault or wrong configuration
  • One channel of the SVOFF input failed
Field note: The first cause is the most common in the field — check it first, then work through the rest.

Step-by-step field fix

  1. Identify what drives the SVOFF input in the cell (PLC program, safety relays)
  2. Check both channels of the SVOFF wiring
  3. Review UOP/I/O configuration if the input should not be used
Safety first: For FANUC srvo-280, 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: Identify what drives the SVOFF input in the cell (PLC program, safety relays). 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-280 belongs to the safety chain & e-stop family. On FANUC srvo-280 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-280 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-280 runs: e-stop / door / curtain -> safety relay (dual channel) -> controller safety input -> motor-off and brake apply.

FANUC srvo-280 is sometimes designed behaviour, not a fault - Releasing the enabling device (three-position switch) in manual mode triggers a protective stop by design, yet plenty of sites report it as an alarm. The switch enables only in the middle position; fully released or pushed through both open - and pushing through is the instinctive panic reaction, which is exactly what the designers used. Knowing that clears a good share of mysterious protective stops. The real fault is worn contacts inside the switch, showing up as poor contact in the middle position.

Field notes on this page cover FANUC srvo-280 (SVOFF Input); 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-280 alarm mean?

The SVOFF (servo off) input signal is active - an external device is requesting servo power off. In our FANUC service archive this alarm on R-30iA / R-30iB / R-30iB Plus systems shows up constantly, and the first on-site inspection almost always locates it. FANUC srvo-280 sits in the safety chain & e-stop family; on our work orders the highest-frequency trigger for this code is "External servo-off device active (PLC, safety device)".

QCan I clear a FANUC srvo-280 alarm myself?

Whether FANUC srvo-280 clears on its own depends on the outcome of "Identify what drives the SVOFF input in the cell (PLC program, safety relays)". Finish the flow with "Review UOP/I/O configuration if the input should not be used" to confirm FANUC srvo-280 - do not skip it. If that step is clean, the second most frequent cause on FANUC srvo-280 is "SVOFF wiring fault or wrong configuration". If FANUC srvo-280 returns after two clears, or the checks point at External servo-off device active (PLC, safety device), stop the cell and call a professional robot repair engineer.

QA safety-chain fault like FANUC srvo-280 stops the line - how fast can you be here?

The commonest causes we see on FANUC srvo-280 are "External servo-off device active (PLC, safety device), SVOFF wiring fault or wrong configuration, One channel of the SVOFF input failed", so we stock the van against those. For FANUC srvo-280 specifically, we stock along the loop: safety relays, common door switches, e-stop buttons, light-curtain pairs and terminal blocks. For FANUC srvo-280, 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-280 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.

This page on FANUC srvo-280 is based on the field experience of the Henghuan Robotics repair team. Alarm explanations are our own summary for troubleshooting reference and may differ across controller and software versions — if unsure, verify against FANUC documentation or reach out to us. Henghuan is an independent service provider with no affiliation or endorsement by FANUC.