What the SRVO-271 alarm means

The external emergency stop line status is inconsistent between the two safety chains. This fault ranks high in our FANUC R-30iA / R-30iB / R-30iB Plus service records, and the first site inspection usually finds the source.

Most common causes

  • External E-stop wired to only one chain
  • Contact failure on one channel of the external device
  • Wiring fault between external device and controller
Field note: The first cause shows up most on real machines, so verify it before you go further.

Step-by-step field fix

  1. Verify the external E-stop is wired to both chains (EXEMG terminals)
  2. Test the external device contacts
  3. Trace the cable run for damage
Safety first: For FANUC srvo-271, 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. What you can check yourself first is Verify the external E-stop is wired to both chains (EXEMG terminals); the e-stop chain and safety circuit handling is not a DIY job.

How we diagnose safety-chain faults on site

FANUC srvo-271 belongs to the safety chain & e-stop family. On FANUC srvo-271 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-271 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-271 runs: e-stop / door / curtain -> safety relay (dual channel) -> controller safety input -> motor-off and brake apply.

On FANUC srvo-271 the field usually reports External E-stop wired to only one chain, but the check that matters is not continuity: The point of a safety loop is not whether it conducts but whether both channels conduct together. The relay compares channels; if one opens tens of milliseconds early it latches as a channel fault. The commonest causes are plain: oxidised door-switch contacts raising contact resistance, or one loose terminal. We measure segment by segment - pendant e-stop, panel e-stop, external e-stop, safety door - and lock onto whichever segment reads differently on the two channels.

Field notes on this page cover FANUC srvo-271 (EXEMG1 Status 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-271 alarm mean?

The external emergency stop line status is inconsistent between the two safety chains. This fault ranks high in our FANUC R-30iA / R-30iB / R-30iB Plus service records, and the first site inspection usually finds the source. FANUC srvo-271 sits in the safety chain & e-stop family; on our work orders the highest-frequency trigger for this code is "External E-stop wired to only one chain".

QCan I clear a FANUC srvo-271 alarm myself?

Whether FANUC srvo-271 clears on its own depends on the outcome of "Verify the external E-stop is wired to both chains (EXEMG terminals)". Finish the flow with "Trace the cable run for damage" to confirm FANUC srvo-271 - do not skip it. If that step is clean, the second most frequent cause on FANUC srvo-271 is "Contact failure on one channel of the external device". If FANUC srvo-271 returns after two clears, or the checks point at External E-stop wired to only one chain, stop the cell and call a professional robot repair engineer.

QA safety-chain fault like FANUC srvo-271 stops the line - how fast can you be here?

The commonest causes we see on FANUC srvo-271 are "External E-stop wired to only one chain, Contact failure on one channel of the external device, Wiring fault between external device and controller", so we stock the van against those. For FANUC srvo-271 specifically, we stock along the loop: safety relays, common door switches, e-stop buttons, light-curtain pairs and terminal blocks. For FANUC srvo-271, 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-271 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-271 was written by the Henghuan Robotics repair team from field service experience. Alarm descriptions are our own summary for troubleshooting reference and may vary by controller and software version — when in doubt, check your FANUC documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by FANUC.