What the C152 alarm means

The TCP approached a configured safety plane/boundary and the safety system stopped the robot to keep it inside the protected workspace. 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

  • Safety planes configured too tight for the real program path
  • Workpiece or fixture inside the safety zone
  • Safety settings changed without updating the program
  • TCP offset set incorrectly so the real tool tip is outside the computed zone
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. Verify the 3D graphics position matches the real robot before anything else
  2. Adjust the safety plane limits in Installation > Safety to match the real cell
  3. Correct the TCP if the offset is wrong
  4. Move the fixture/workpiece out of the safety zone
  5. Run the program at reduced speed to confirm clearance
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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Hotline: +86-20-39029800 · WhatsApp: +86-188-1886-2860

Related Safety Chain & E-Stop alarms

C191A1 — Safety Violation — Joint Position Limit Violated C191A2 — Safety Violation — Joint Speed 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 C152 alarm mean?

The TCP approached a configured safety plane/boundary and the safety system stopped the robot to keep it inside the protected workspace. In field practice it belongs to the safety chain & e-stop family of faults.

QCan I clear a Universal Robots C152 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.