The Robotiq Palletizing Workcells (PE Series and AX Series) can interface with external safety devices (safety laser scanners, light curtains, interlock switches, etc.) to ensure a safe operation. Knowing how the system is expected to behave in each operating mode, and which action brings it back to normal operation, helps integrators design the cell and helps operators understand what they see on the floor.

This article summarizes the expected system behavior in normal operating conditions, as documented in the instruction manuals and in the Palletizing Workcell Safety Package Guide. The PAL Ready configuration is based on the PE20: its safety behavior is the same as the PE20. The installer remains responsible for performing a complete risk assessment of the final application.

Stop categories

The workcell behavior is described using the stop categories of IEC 60204-1:

Please refer to IEC 60204-1 for additional information on stop categories.

Operating modes

[INSERT IMAGE emergency stop button on the UR teach pendant here]

Safety packages and hardware per model

The safety hardware included with the workcell depends on the model and on the selected Safety Package:

Model No safety package 1-Scanner package 3-Scanner package Reduced Mode
PE10 No safety relay Safety relay and reset push-button station Not offered Not supported
PE20 No safety relay Safety relay and reset push-button station Safety relay and reset push-button station Supported (PE20 exclusive), through the safety relay
AX10 Safety relay (always included) Safety relay Safety relay Not supported
AX20 / AX30 Safety relay (always included) Safety relay Safety relay Not supported

On the PE10, a Reduced Mode behavior can still be engineered by the integrator with their own safety relay and risk assessment; it is not part of the Robotiq Safety Package offer.

[INSERT IMAGE Safety Package layout / scanner zones here]

Expected robot behavior

In Normal mode, the robot operates up to the safety limits configured on the robot:

Model Force (N) Power (W) Speed (mm/s)
PE10   Up to 1,000 Up to 5,000
PE20 Up to 400 Up to 1,000 Up to 2,500

When a safety function triggers, the robot behaves as follows:

Operation mode Robot behavior
Robot stop (Protective stop) Stop Category 2
Safeguard stop Stop Category 2
Emergency stop Stop Category 1
Reduced mode Refer to the Universal Robots user manual for more details

Events and recovery actions

The table below applies to configurations equipped with the safety relay and safety laser scanners. The general rule: entering a safety mode is automatic, leaving it always goes through the safeguard reset push-button. There is no auto-reset variant offered with the relay and scanners, and a single push-button resets the whole relay.

Event System behavior Stop category To resume
A person enters the Reduced Mode zone (PE20 only) The robot switches to the reduced safety limits automatically and keeps palletizing None (the robot keeps moving) No action needed
The person leaves the Reduced Mode zone The robot stays at the reduced limits (the safety relay latches) None Press the safeguard reset push-button to return to normal speed
A person enters the Safeguard Stop zone The robot performs a safeguard stop and the program pauses. On the AX Series, the linear axis also stops (stop command within 120 ms; the axis is considered fully stopped after 400 ms) Category 2 None while the zone is occupied
The person leaves the Safeguard Stop zone The system stays stopped (the safety relay latches) Category 2, held Press the safeguard reset push-button; the program resumes. The reset only takes effect once all monitored zones are clear
The emergency stop button is pressed The robot, the linear axis (AX Series) and the Smart Infeed stop; power is removed once the stop is achieved Category 1 Release the emergency stop button, then follow the robot restart procedure described in the instruction manual

Restarting the program after a safeguard reset

When the program resumes after a safeguard reset, the robot restart can be abrupt and may cause a protective stop. To obtain a smooth restart, enable the following option in the Copilot URCap configuration:

“Use Copilot to manage soft speed transition when resuming from a safeguard stop”

If the cell uses EtherNet/IP communication, this option can conflict with external control (Error 2000). In that case, keep the option disabled and configure the safeguard stop recovery behavior in the Universal Robots safety settings instead. See EtherNet/IP Communication Conflict with Robotiq Copilot Soft Speed Transition, Error 2000.

Model-specific notes

AX Series

PE20

[INSERT IMAGE W103 wiring to the robot safety inputs here]

Reaction times

Vacuum gripper behavior on an emergency stop

When the e-Stop button is pressed, the behavior of the vacuum gripper depends on its supply source. The user has the responsibility to perform a risk assessment and choose the appropriate option.

Caution: a loss of vacuum can also occur due to a power failure or an air supply interruption, regardless of the supply source.

After an emergency stop or a collision

After a collision or an emergency stop, an inspection of the workcell must be performed before resuming the use of the machine. Special attention must be given to the pedestal, the cable management system, and the gripper components. Contact Robotiq Support if any sign of damage is detected.

Conclusion

The behavior of the Robotiq Palletizing Workcells is predictable by design: a protective or safeguard stop leaves the system in a controlled Category 2 stop, ready to resume with a single press of the safeguard reset push-button, while an emergency stop performs a Category 1 stop and requires an inspection before restarting. To connect and configure safety devices such as safety laser scanners, refer to the Palletizing Workcell Safety Package Guide available at robotiq.com/support.

 

Need help? Contact Robotiq Support

Updated: September 17, 2026

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Safety Behavior of the PE Series Palletizing Workcell

The Robotiq Palletizing Workcells (PE Series and AX Series) can interface with external safety devices (safety laser scanners, light curtains, interlock switches, etc.) to ensure a safe operation. Knowing how the system is expected to behave in each operating mode, and which action brings it back to normal operation, helps integrators design the cell and helps operators understand what they see on the floor.

This article summarizes the expected system behavior in normal operating conditions, as documented in the instruction manuals and in the Palletizing Workcell Safety Package Guide. The PAL Ready configuration is based on the PE20: its safety behavior is the same as the PE20. The installer remains responsible for performing a complete risk assessment of the final application.

Stop categories

The workcell behavior is described using the stop categories of IEC 60204-1:

  • Category 0 Stop: stops the system by immediate removal of power.
  • Category 1 Stop: a controlled stop; power is removed once the stop is achieved.
  • Category 2 Stop: a controlled stop; power is still available once the stop is achieved.

Please refer to IEC 60204-1 for additional information on stop categories.

Operating modes

  • Normal mode: the palletizer continuously fills pallets when no human operator is in the vicinity of the palletizing cell.
  • Reduced mode (safeguarded operation, available on the PE20 only): the palletizer continues to fill pallets even when an operator enters the palletizing cell. The operator can safely remove a filled pallet or place a pallet in an empty slot. The system will not start to palletize on an empty pallet unless the operator has pressed the Confirm pallet(s) ready button. To obtain this behavior, the Confirm pallet(s) ready checkbox must be ticked in the Installation tab. Allowing cell access to the operator also requires a complete risk assessment and additional parameters (including, but not limited to: robot speed, robot force, safety planes, guardrails).
  • Separation monitoring mode (safeguarded operation): the system stops when a human operator enters the vicinity of the palletizing cell (to manipulate a filled pallet, place a pallet in an empty slot, troubleshoot the system, or any other intervention). In this state, the robot maintains a Category 2 stop. When the safeguards are removed, the system resumes operation in Normal mode.
  • Emergency stop mode: the system enters this mode when the emergency stop (e-Stop) button is pressed. Note that there is no emergency stop button directly on the Robotiq palletizer: the e-Stop button used by the workcell is the one found on the robot teach pendant. Make sure operators know how to stop the system in case of emergency.

 

Safety packages and hardware per model

The safety hardware included with the workcell depends on the model and on the selected Safety Package:

Model No safety package 1-Scanner package 3-Scanner package Reduced Mode
PE10 No safety relay Safety relay and reset push-button station Not offered Not supported
PE20 No safety relay Safety relay and reset push-button station Safety relay and reset push-button station Supported (PE20 exclusive), through the safety relay
AX10 Safety relay (always included) Safety relay Safety relay Not supported
AX20 / AX30 Safety relay (always included) Safety relay Safety relay Not supported

On the PE10, a Reduced Mode behavior can still be engineered by the integrator with their own safety relay and risk assessment; it is not part of the Robotiq Safety Package offer.

 

Expected robot behavior

In Normal mode, the robot operates up to the safety limits configured on the robot:

Model Force (N) Power (W) Speed (mm/s)
PE10   Up to 1,000 Up to 5,000
PE20 Up to 400 Up to 1,000 Up to 2,500

When a safety function triggers, the robot behaves as follows:

Operation mode Robot behavior
Robot stop (Protective stop) Stop Category 2
Safeguard stop Stop Category 2
Emergency stop Stop Category 1
Reduced mode Refer to the Universal Robots user manual for more details

Events and recovery actions

The table below applies to configurations equipped with the safety relay and safety laser scanners. The general rule: entering a safety mode is automatic, leaving it always goes through the safeguard reset push-button. There is no auto-reset variant offered with the relay and scanners, and a single push-button resets the whole relay.

Event System behavior Stop category To resume
A person enters the Reduced Mode zone (PE20 only) The robot switches to the reduced safety limits automatically and keeps palletizing None (the robot keeps moving) No action needed
The person leaves the Reduced Mode zone The robot stays at the reduced limits (the safety relay latches) None Press the safeguard reset push-button to return to normal speed
A person enters the Safeguard Stop zone The robot performs a safeguard stop and the program pauses. On the AX Series, the linear axis also stops (stop command within 120 ms; the axis is considered fully stopped after 400 ms) Category 2 None while the zone is occupied
The person leaves the Safeguard Stop zone The system stays stopped (the safety relay latches) Category 2, held Press the safeguard reset push-button; the program resumes. The reset only takes effect once all monitored zones are clear
The emergency stop button is pressed The robot, the linear axis (AX Series) and the Smart Infeed stop; power is removed once the stop is achieved Category 1 Release the emergency stop button, then follow the robot restart procedure described in the instruction manual

Restarting the program after a safeguard reset

When the program resumes after a safeguard reset, the robot restart can be abrupt and may cause a protective stop. To obtain a smooth restart, enable the following option in the Copilot URCap configuration:

“Use Copilot to manage soft speed transition when resuming from a safeguard stop”

If the cell uses EtherNet/IP communication, this option can conflict with external control (Error 2000). In that case, keep the option disabled and configure the safeguard stop recovery behavior in the Universal Robots safety settings instead. See EtherNet/IP Communication Conflict with Robotiq Copilot Soft Speed Transition, Error 2000.

Model-specific notes

AX Series

  • The safeguard reset must be configured in the robot Safety I/O (Safeguard reset and System Emergency Stopped), even when no physical reset button is installed.
  • If no safeguard device is used, jumpers must be installed on pins 1-2 and 3-4 of the black connector. Otherwise, the following error message appears: “Please use the safeguard reset before starting the linear axis.” See Fixing the “Please use the safeguard reset before starting the linear axis” Error.
  • Safety devices with OSSD outputs cannot be connected directly to the linear axis safety inputs: connect them through a safety relay.

PE20

  • The W103 cable is pre-wired for the safety functions: wires 2 and 3 (Automatic Mode Safeguard Stop) connect to the robot safety inputs CI2/CI3, and wires 8 and 9 (Reduced Mode) connect to CI4/CI5. Refer to the PE20 instruction manual for the wiring details.

 

Reaction times

  • Safety relay: 16 ms (PE Series), 50 ms (AX Series).
  • Safety laser scanner (SICK nanoScan3): 70 ms.

Vacuum gripper behavior on an emergency stop

When the e-Stop button is pressed, the behavior of the vacuum gripper depends on its supply source. The user has the responsibility to perform a risk assessment and choose the appropriate option.

  • Robot control box supply (any 24 V terminal): the vacuum gripper remains powered. If an object is detected, the vacuum level continues to be regulated and the object is not lost. The PowerPick vacuum grippers connect to the robot control box supply.
  • Robot tool supply (tool connector): power to the vacuum gripper is lost. The vacuum level drops to ambient pressure and the object is lost. It is not recommended to connect the vacuum gripper to the tool connector.

Caution: a loss of vacuum can also occur due to a power failure or an air supply interruption, regardless of the supply source.

After an emergency stop or a collision

After a collision or an emergency stop, an inspection of the workcell must be performed before resuming the use of the machine. Special attention must be given to the pedestal, the cable management system, and the gripper components. Contact Robotiq Support if any sign of damage is detected.

Conclusion

The behavior of the Robotiq Palletizing Workcells is predictable by design: a protective or safeguard stop leaves the system in a controlled Category 2 stop, ready to resume with a single press of the safeguard reset push-button, while an emergency stop performs a Category 1 stop and requires an inspection before restarting. To connect and configure safety devices such as safety laser scanners, refer to the Palletizing Workcell Safety Package Guide available at robotiq.com/support.

 

Need help? Contact Robotiq Support

Updated: September 17, 2026