What the C154 alarm means

The robot cannot move linearly through the commanded point because it is in (or too close to) a kinematic singularity. 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

  • MoveL commanded straight through a wrist singularity
  • Wrist axes J4/J6 nearly parallel at the via point
  • Robot asked to keep TCP orientation while passing through the shoulder singularity
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. Use joint-space moves (MoveJ) through the singular region
  2. Reteach the via point slightly off the singularity
  3. Change the tool orientation to avoid wrist alignment
  4. Reduce speed when passing near singularities
  5. For long straight paths, split the move around the singular posture
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.

Get a Free Remote Diagnosis See Repair Services

Hotline: +86-20-39029800 · WhatsApp: +86-188-1886-2860

Related Motion & Path alarms

C150 — Protective Stop — Position Close to Joint Limits C153 — Protective Stop — Position Deviates from Path C155 — Protective Stop — Robot Cannot Maintain Position C157 — Protective Stop — Collision Detected
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 C154 alarm mean?

The robot cannot move linearly through the commanded point because it is in (or too close to) a kinematic singularity. In field practice it belongs to the motion & path family of faults.

QCan I clear a Universal Robots C154 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.