How-to

Recover from a stop on the Agilent Bravo

Bring the Bravo back after a light-curtain break or an emergency stop, and clear the gripper safe-plane error.

The Bravo switches its motors off when someone reaches through the light curtain or presses the emergency stop. The axes keep their position reference, so recovery switches them back on where they stand, without homing.

Prerequisites

An Agilent Bravo, powered on, with its connector installed and initialized
A script that drives the Bravo with the Liquid Handling SDK's Bravo class

After a light-curtain break or an emergency stop

The Bravo stops, and the status light blinks red. The axes that stopped switch their motors off, and the next move fails until they're back on. To recover:

Stop sending commands, and check the deck. Take out anything that's in the head's or the gripper's path.
Release the emergency stop if it was pressed.
Initialize and activate the Bravo again:
```
await bravo.initialize()
await bravo.activate()
```
initialize() brings the axes back to a state they can move from. activate() makes the Bravo ready for the next step, parks the gripper if it's extended, and sets the status light back.
If a move still fails, restart the connector in GroundControl, then run your script's setup again: configure(), initialize(), and activate(). Initialize homes any axis that lost its position.
If the Bravo still doesn't recover, power-cycle it, restart the connector, and run the setup again.

Activating and initializing make the Bravo ready to move again, and initializing homes any axis that needs it. Clear the deck and keep your hands outside the light curtain before you run either one.

The status light

The connector watches for faults in the background. When the emergency stop engages or any axis except BravoG switches off, it sets the light to blink red fast.

The light stays red after the fault clears, so the stop stays visible until someone acts on it. activate() sets it back once every axis is on again.

Gripper extended past the safe plane

The head only moves while the gripper is retracted. If the gripper is extended, every head move returns Gripper Zg is extended past the safe plane; retract the gripper before moving the head. Run await bravo.activate(), which parks the gripper, then send the head move again.

If the gripper holds a plate, it stays extended so it doesn't drop the plate, and you see Gripper is holding labware; place it before retracting. Put the plate down at a deck location first, then activate again.

Retract the gripper before you move the head. An extended gripper sits below the head and can hit labware or accessories on the deck.

Gripper jaws closed on the head

If the gripper jaws close while the head is between them, they clamp the head. To free it:

Power off the Bravo.
Pry the gripper arms apart by hand.
Remove the head.

Then put the head back, power the Bravo on, restart the connector, and run your script's setup again.

Move the head clear of the gripper before you close the gripper jaws.

Behaviors to expect

You see	It means
Positions read about `0.0001` after homing	The home position. It's the safest position to start from
`BravoG` shows `enabled: false` while the Bravo is idle	The connector switches the jaw motor off between moves, so the jaws hold a plate mechanically

Next steps

Calibrate teachpoints: set the deck positions before the first pipetting run.
Error handling: how errors from liquid handlers reach your workflow.

Last updated Nov 11, 2026

Calibrate teachpoints on the Agilent Bravo

Set the Bravo's deck positions from the cross on one location, adjust single locations, and check the result.

Tip handling on the Agilent Bravo

Picking up and dropping tips with the Agilent Bravo.