What the 1001 alarm means

After a safety-related stop, KSS requires the operator to acknowledge the operator-safety message before the drives can be re-enabled — the robot will not move until the acknowledgment button is pressed and held for the configured time. This is a routine repair in our workshop for KUKA KRC2 / KRC4 / KRC5 (KSS) systems, and we normally pin it down during the first site check.

Most common causes

  • E-stop or safety door released but the acknowledgment button never pressed
  • Acknowledgment button pressed too briefly (default hold time is about 1 s)
  • Faulty or miswired operator-safety acknowledgment input on the X11 safety interface
  • Safety configuration expecting the acknowledgment from a different device (SmartPad vs. external button)
Field note: Begin with the first item in the list; it has a far higher on-machine occurrence rate than the others.

Step-by-step field fix

  1. Confirm every E-stop is released and all safety doors are closed
  2. Press and HOLD the operator-safety acknowledgment button until the SmartHMI message clears
  3. Open Diagnosis → Message Log on the SmartPad and clear any remaining pending messages
  4. If the message returns immediately, verify the X11 acknowledgment wiring and the safety configuration in WorkVisual
  5. Power-cycle the controller once if the acknowledgment state appears latched in error
Safety first: For KUKA 1001, 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 Confirm every E-stop is released and all safety doors are closed; the e-stop chain and safety circuit handling is not a DIY job.

How we diagnose safety-chain faults on site

KUKA 1001 belongs to the safety chain & e-stop family. On KUKA 1001 the failing stage is SIB safety input board / SafeOperation option on the KRC2 / KRC4 / KRC5 - continuity of one series loop: e-stop buttons, door switches, light curtains, safety relays and the enabling device. We start reading KUKA 1001 at the smartPAD message window (KSS message numbers: 1xxx operator, 2xxxx drive) with KPP/KSP module LEDs.

The chain involved in KUKA 1001 runs: e-stop / door / curtain -> safety relay (dual channel) -> controller safety input -> motor-off and brake apply.

KUKA 1001 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 KUKA 1001 (Operator Safety Acknowledgment Required); written by the Henghuan repair team, updated 2026-10-01.

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Related Safety Chain & E-Stop alarms

1002 — Drives-On Not Asserted ($DRIVES_ON) 1010 — Move Enable Missing — E-Stop or Safety Relay Open 15074 — Safety Junction Error in Drive — Channel N
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: we also keep field-fix libraries for ABB · Yaskawa · Universal Robots and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the KUKA 1001 alarm mean?

After a safety-related stop, KSS requires the operator to acknowledge the operator-safety message before the drives can be re-enabled — the robot will not move until the acknowledgment button is pressed and held for the configured time. This is a routine repair in our workshop for KUKA KRC2 / KRC4 / KRC5 (KSS) systems, and we normally pin it down during the first site check. KUKA 1001 sits in the safety chain & e-stop family; on our work orders the highest-frequency trigger for this code is "E-stop or safety door released but the acknowledgment button never pressed".

QCan I clear a KUKA 1001 alarm myself?

Whether KUKA 1001 clears on its own depends on the outcome of "Confirm every E-stop is released and all safety doors are closed". Finish the flow with "Power-cycle the controller once if the acknowledgment state appears latched in error" to confirm KUKA 1001 - do not skip it. If that step is clean, the second most frequent cause on KUKA 1001 is "Acknowledgment button pressed too briefly (default hold time is about 1 s)". Do not chase takt through a repeating KUKA 1001. Left alone, safety chain & e-stop faults tend to graduate from repairable to must-replace.

QA safety-chain fault like KUKA 1001 stops the line - how fast can you be here?

The commonest causes we see on KUKA 1001 are "E-stop or safety door released but the acknowledgment button never pressed, Acknowledgment button pressed too briefly (default hold time is about 1 s), Faulty or miswired operator-safety acknowledgment input on the X11 safety interface", so we stock the van against those. For KUKA 1001 specifically, we stock along the loop: safety relays, common door switches, e-stop buttons, light-curtain pairs and terminal blocks. For KUKA 1001, 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 KUKA 1001 shows on the smartPAD message window (KSS message numbers: 1xxx operator, 2xxxx drive) with KPP/KSP module LEDs and what the machine was doing - phone or video triage is free.

The content on KUKA 1001 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 KUKA documentation, or contact us to confirm. Henghuan is an independent service provider with no affiliation or endorsement by KUKA.