What the C191A1 alarm means

A configured safety joint position limit was exceeded; this is a safety-system stop, stronger than a normal protective stop. This is a high-frequency ticket for our Universal Robots repair team, and on CB3 / e-Series (UR5/UR10/UR16/UR20) systems one inspection usually identifies the fault.

Most common causes

  • Program moving outside the configured safety joint limits
  • Safety limits set before a tool/process change
  • Jogging past the limit in reduced mode
  • Safety file corrupted
Field note: The top-listed cause has the highest hit rate, so checking it first narrows things down fast.

Step-by-step field fix

  1. Jog back inside the limit in joint mode
  2. Review Installation > Safety joint limits against the real program envelope
  3. Reload a known-good safety configuration if the file is suspect
  4. Verify with the safety engineer before widening any limit
  5. Power-cycle and retest at low speed
Safety first: For Universal Robots c191a1, 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: Jog back inside the limit in joint mode. 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

Universal Robots c191a1 belongs to the safety chain & e-stop family. On Universal Robots c191a1 the failing stage is configurable safety functions (limits, safety IO, force and power limits; finer on e-Series) on the UR control box (CB3 / e-Series) - continuity of one series loop: e-stop buttons, door switches, light curtains, safety relays and the enabling device. We start reading Universal Robots c191a1 at the PolyScope event and alarm pages; codes carry a C prefix (C15x, C5x, C7x).

The chain involved in Universal Robots c191a1 runs: e-stop / door / curtain -> safety relay (dual channel) -> controller safety input -> motor-off and brake apply.

On Universal Robots c191a1 (field clue usually Program moving outside the configured safety joint limits) we have one hard rule: On this family we have a hard rule: no bypassing the safety loop, no forcing contactors closed, ever. Some sites jumper the door switch to keep running - that removes the entire protection function, and when something happens there is no protective action and no defensible account of responsibility. We have seen a crush injury caused by exactly that jumper, so we would rather wait for parts than do it. If a customer has already jumpered it, we restore the circuit first and then diagnose the real fault.

Field notes on this page cover Universal Robots c191a1 (Safety Violation — Joint Position Limit Violated); written by the Henghuan repair team, updated 2026-10-01.

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Related Safety Chain & E-Stop alarms

C152 — Protective Stop — Position Close to Safety Plane Limits C191A2 — Safety Violation — Joint Speed Limit Violated
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 Kawasaki · Staubli · Epson and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the Universal Robots c191a1 alarm mean?

A configured safety joint position limit was exceeded; this is a safety-system stop, stronger than a normal protective stop. This is a high-frequency ticket for our Universal Robots repair team, and on CB3 / e-Series (UR5/UR10/UR16/UR20) systems one inspection usually identifies the fault. Universal Robots c191a1 sits in the safety chain & e-stop family; on our work orders the highest-frequency trigger for this code is "Program moving outside the configured safety joint limits".

QCan I clear a Universal Robots c191a1 alarm myself?

Whether Universal Robots c191a1 clears on its own depends on the outcome of "Jog back inside the limit in joint mode". Finish the flow with "Power-cycle and retest at low speed" to confirm Universal Robots c191a1 - do not skip it. If that step is clean, the second most frequent cause on Universal Robots c191a1 is "Safety limits set before a tool/process change". Two attempts and still there means stop: Universal Robots c191a1 involves the e-stop chain and safety circuit, and running Universal Robots c191a1 on can turn a repairable fault into a replacement.

QA safety-chain fault like Universal Robots c191a1 stops the line - how fast can you be here?

The commonest causes we see on Universal Robots c191a1 are "Program moving outside the configured safety joint limits, Safety limits set before a tool/process change, Jogging past the limit in reduced mode", so we stock the van against those. For Universal Robots c191a1 specifically, we stock along the loop: safety relays, common door switches, e-stop buttons, light-curtain pairs and terminal blocks. For Universal Robots c191a1, 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 Universal Robots c191a1 shows on the PolyScope event and alarm pages; codes carry a C prefix (C15x, C5x, C7x) and what the machine was doing - phone or video triage is free.

This page on Universal Robots c191a1 was 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.