What the C191A2 alarm means

A joint exceeded its configured speed limit; the safety system initiated a stop. This is one of the faults our repair team handles on Universal Robots CB3 / e-Series (UR5/UR10/UR16/UR20) systems — the cause is usually identifiable within the first on-site inspection.

Most common causes

  • Program speed set above the configured joint speed limit
  • High acceleration through a singularity causing a joint velocity spike
  • Speed limit reduced after a safety review without updating programs
Field note: the first item on this list is what we find most often on real machines. Check it before you go deeper.

Step-by-step field fix

  1. Reduce joint acceleration and speed in the offending move
  2. Check the safety joint speed limit settings
  3. Avoid fast wrist flips near singularities
  4. Retest at reduced speed and increase only within the configured limit
  5. Document any safety-limit change in the cell safety file
Safety first: never bypass safety circuits or force contactors closed. If the alarm involves E-stop chains, brakes or drive power, and you are not a trained robot technician, contact a professional — wrong moves here can cost you a robot or an injury.

Still stuck? Get an engineer on the phone — right now

Tell us the alarm code, the robot model and what was happening when the alarm came up. Our engineers run these diagnostics every day, and remote diagnosis by phone or video call is free.

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Related Safety Chain & E-Stop alarms

C152 — Protective Stop — Position Close to Safety Plane Limits C191A1 — Safety Violation — Joint Position Limit Violated
Other brands: we also keep field-fix libraries for Kawasaki · Staubli · Epson and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the Universal Robots C191A2 alarm mean?

A joint exceeded its configured speed limit; the safety system initiated a stop. In field practice it belongs to the safety chain & e-stop family of faults.

QCan I clear a Universal Robots C191A2 alarm myself?

Sometimes. Work through the step-by-step checks on this page — the first listed cause is what we find most often in the field. If the alarm returns after two attempts, or the fault involves power, brakes or safety circuits, stop and call a qualified robot service engineer.

QHow fast can a Henghuan engineer help?

On-site response in the Pearl River Delta within 30 minutes to 3 hours, across mainland China in 1-3 business days, and worldwide within 2-5 business days. Remote diagnosis by phone/WhatsApp/video is available immediately.

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 Universal Robots documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by Universal Robots.