Universal Robots Forum

IO-state and power-management during E-stop conditions

Is there an overview of how power and signal-status in the IO-connector in the robot-head is effected during different E-stop categories. I am unable to derive this from the UR manual (cant find it)

I am looking for a table or somehthing along the lines of:
E-stop IO-signal status IO-power status
CAT0 unpowered unpowered
CAT1 At last known state powered
CAT2 At last known state powered

During an E-Stop (CAT1), the power is removed from the robot arm.
Hence, in any E-Stop condition, the Tool IO will become unpowered.
When power is restored, the output states will by default be restored to the value before the power off.

For Protective Stops and Safeguard (CAT2), the power is kept on the arm. And the IO states will persist.

Also check out the Safety FAQ.

The E-Stop is CAT1. " Robot motion is stopped with power available to the robot to achieve the stop and then removal of power when the stop is achieved."
But, for exemple, if my robot is static (not move), When I push the E-stop (Teach Pendant Button), the power is removed and the arm of robot falls of several millimetres before the brakes block.

Why the brakes are not active before the power is removed? In my case, in emergency case the falls of my arm of UR3 is impossible (even one millimetre). How I active the brakes BEFORE remove the power? or How I avoid the fall of the robot when I push the button E-Stop?

Thank you for you help.
Best regards.

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