Universal Robots e-Series — Protective Stop Recovery

Universal Robots · beginner · 15 min

A UR e-Series Protective Stop shows a red PolyScope popup naming the safety function that tripped. Read the reason, remove the cause, then unlock and restart — and use Recovery mode if a joint is out of limits.

ℹ️ A Protective Stop is the robot's safety system doing its job. The PolyScope popup tells you exactly which limit was exceeded — read it before you clear it.

What a Protective Stop is

On a Universal Robots e-Series cobot, a Protective Stop halts motion when a configured safety function is exceeded — a force / torque limit, a position or speed limit, a safety-plane violation, or a protective-stop input. PolyScope shows a red popup on the teach pendant naming the reason. Unlike an emergency stop, a protective stop is a controlled stop you recover from once the cause is gone.

Step-by-step recovery

  1. Read the popup. It names the safety function that triggered (e.g. "Position limit," "Force limit," "Protective stop input"). This is the single most important piece of information — it tells you what to fix.
  2. Remove the cause. Depending on the reason: take the load or obstruction off the tool, back the arm away from the surface it pushed into, clear whatever opened the protective-stop input, or reduce the speed/payload that exceeded a limit.
  3. Unlock the protective stop. On the teach pendant, dismiss the popup and press the on-screen control to unlock / enable the robot (or send "unlock protective stop" then "play" from a PLC via the Dashboard Server if running externally). This closes the popup and releases the protective-stop state.
  4. Restart the program from a safe point per your cell's start procedure.

Recovery mode (joint outside a safety limit at start-up)

If, at power-up, a joint position is outside a configured safety limit, PolyScope activates Recovery mode. In Recovery mode you cannot run programs, but you can bring the arm back in range by either:

  • Freedrive — hold the Freedrive button and physically guide the joint back within limits, or
  • the Move tab in PolyScope to jog the joint back inside its limit.

Once every joint is within limits, exit Recovery and the robot returns to normal operation.

Repeated protective stops

If the robot trips the same protective stop repeatedly during a task, the safety limit is set tighter than the task needs — review the force/speed/position limits in the Safety configuration (requires the safety password) against the real application rather than working around the stop. Never loosen a safety limit without a risk assessment.

Key points

  • A Protective Stop names the tripped safety function (force, position, speed, safety plane, or protective-stop input) in the PolyScope popup — read it first.
  • Recover by removing the cause, then unlocking/enabling the robot on the teach pendant (or via the Dashboard Server externally).
  • If a joint is outside a safety limit at power-up, PolyScope enters Recovery mode — programs can't run.
  • In Recovery mode, use Freedrive or the Move tab to bring the joint back within limits, then exit.
  • Repeated stops mean the safety limit is tighter than the task — review it (safety password), never work around it without a risk assessment.

Codes and symptoms

Protective Stop — Safety function exceeded
A force/position/speed limit or protective-stop input tripped; the PolyScope popup names which one.
Recovery mode — Joint outside safety limit
At power-up a joint is beyond a configured safety limit; use Freedrive or the Move tab to bring it back in range.