What the SRVO-232 alarm means

The NTED (external enabling device) input is in an abnormal state - the external enable signal chain disagrees or is stuck. Our engineers run into this alarm every week on FANUC R-30iA / R-30iB / R-30iB Plus controllers, and a single on-site inspection usually identifies the problem.

Most common causes

  • External enabling device (e.g. External deadman/enable switch) failure
  • Wiring fault on the NTED inputs
  • One channel stuck on
Field note: In our repair stats the first cause has the highest hit rate, so confirm it first before digging further.

Step-by-step field fix

  1. Check the external enable device operation on both channels
  2. Verify NTED wiring against the controller terminal diagram
  3. Replace the external device if contacts are unreliable
Safety first: For FANUC srvo-232, 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: Check the external enable device operation on both channels. 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-232 belongs to the safety chain & e-stop family. On FANUC srvo-232 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-232 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-232 runs: e-stop / door / curtain -> safety relay (dual channel) -> controller safety input -> motor-off and brake apply.

On FANUC srvo-232 the field usually reports External enabling device (e.g. External deadman/enable switch) failure, 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-232 (NTED Input Abnormal); written by the Henghuan repair team, updated 2026-10-01.

Not sure? Don't force it — contact an engineer

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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-232 alarm mean?

The NTED (external enabling device) input is in an abnormal state - the external enable signal chain disagrees or is stuck. Our engineers run into this alarm every week on FANUC R-30iA / R-30iB / R-30iB Plus controllers, and a single on-site inspection usually identifies the problem. FANUC srvo-232 sits in the safety chain & e-stop family; on our work orders the highest-frequency trigger for this code is "External enabling device (e.g. External deadman/enable switch) failure".

QCan I clear a FANUC srvo-232 alarm myself?

Whether FANUC srvo-232 clears on its own depends on the outcome of "Check the external enable device operation on both channels". Finish the flow with "Replace the external device if contacts are unreliable" to confirm FANUC srvo-232 - do not skip it. If that step is clean, the second most frequent cause on FANUC srvo-232 is "Wiring fault on the NTED inputs". After clearing FANUC srvo-232, watch it for one shift. A second trip means stop and let an engineer arrive with the right test gear for the e-stop chain and safety circuit.

QA safety-chain fault like FANUC srvo-232 stops the line - how fast can you be here?

The commonest causes we see on FANUC srvo-232 are "External enabling device (e.g. External deadman/enable switch) failure, Wiring fault on the NTED inputs, One channel stuck on", so we stock the van against those. For FANUC srvo-232 specifically, we stock along the loop: safety relays, common door switches, e-stop buttons, light-curtain pairs and terminal blocks. For FANUC srvo-232, 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-232 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 content on FANUC srvo-232 was written by Henghuan Robotics service engineers from hands-on repair experience. Alarm descriptions are our own reference summary and may differ by controller or software version — defer to FANUC documentation, or contact us to confirm. Henghuan is an independent service provider with no affiliation or endorsement by FANUC.