Opentronssetupguides

Disclaimer

This Copy is from Opentrons and is Copyrighted, © 2023 Opentrons, it is available at https://support.opentrons.com/ , if you have any questions or concerns just email [e-mail]

Citation

Citation:

Opentrons. (2023). How Labware Offsets work on the OT-2. Retrieved May 19, 2023, from https://support.opentrons.com/s/article/How-Labware-Offsets-work-on-the-OT-2

How Labware Offsets work on the OT-2

Learn how Labware Offset data is utilized during the Labware Position Check workflow when running a protocol on the OT-2.

In this article:

1. What is a Labware Offset?

2. What is Labware Position Check?

3. Should I always use Labware Position Check?

4. How do I run Labware Position Check?

What is a Labware Offset?

A Labware Offset is data that helps the OT-2 determine what small adjustments need to be made for a pipette to go to the right place on a specific labware in a specific deck slot. Labware Offset data is unique to a specific combination of labware definition, deck slot, and OT-2.

To create Labware Offset data, you perform Labware Position Check before running your protocol. As of version 6.0 of the Opentrons App, you can apply previously calculated offsets — even across different protocols — as long as they are for the same type of labware in the same deck slot on the same robot.

What is Labware Position Check?

Labware Position Check is the recommended guided workflow that Labware Offsets are created through (which are used to increase the precision of your protocol). When you run Labware Position Check, the OT-2’s will move to the top center of the A1 well of each piece of labware. If the pipette nozzle or tip is not centered, you can reveal the OT-2’s jog controls to make adjustments. Whatever adjustment you make will be applied to all wells on the labware in that slot. Offset data is an x, y, z vector measured to the nearest 0.1 mm.

As of software version 6.0.0, the Labware Offset data created through the Labware Position check is stored on the OT-2. Since it is now local to the OT-2, it is possible to apply previous Labware Offsets — even across different protocols — as long as they are for the same type of labware in the same deck slot on the same robot.

Should I always use Labware Position Check?

Opentrons recommends using Labware Position Check before every protocol run, but it is not mandatory. If you have saved Labware Offset data and apply it before running Labware Position Check, the pipette will start at those saved positions — you only have to double-check their accuracy.

Labware Position Check is intended to correct for minor variances. Opentrons does not recommend using Labware Position Check to compensate for large positional adjustments. Needing to set large labware offsets could indicate a problem further upstream, such as bad deck or pipette calibration, or an incorrect labware definition. We recommend

checking your OT-2's calibration health to first determine which components might need further attention.

How do I run Labware Position Check?

The Opentrons App will recommend that you run Labware Position Check as part of the setup for your protocol.

After

selecting the protocol you want to run, then choosing to run it on a specific OT-2, you’ll be taken to the protocol setup page. Under Step 2: Labware Setup, click Run Labware Position Check to begin the guided workflow.

Follow the guided workflow in the app to check labware positions. If needed, reveal the jog controls and adjust the position of the pipette.

As you jog the pipette, the app will show updated Labware Offset values. When you have aligned the pipette properly on all labware, click Close and Apply Labware Offset Data. At this point, you can proceed to run your protocol.

After this, you can select Proceed to run (with applied Labware Offset data) or go through the Labware Position Check again to reset or change Labware Offsets.

When your run is complete, you can view the Labware Offset data that was applied to the run by clicking the chevron next to the run record on the robot’s device detail page. Labware Offset data for up to 20 runs are stored on the robot, and can be accessed and applied from the same computer or another computer connecting to the same robot.

If you re-run your protocol (or run a protocol that uses the same type of labware, in the same slot, on the same robot), the app will automatically prompt you to apply your previously stored Labware Offset data.

You can either use those exact offsets, or if you run Labware Position Check again they will be used as the starting point for jogging the pipette, rather than 0.00 on each axis.

Live chat:

Chat with an Expert

Copyright © 2023 Opentrons

⌘J

Skip to Main Content

Opentrons Help Center

• Home

• Topics

Expand search

• OT-2: CALIBRATION

Troubleshooting calibration issues

Troubleshooting calibration issues

Important Note: the information in this article regarding the tip probe applies only to users running software released before version 4.0.0

There are two types of issues related to calibration: technical issues that block the calibration processes and technical issues related to the robot's movement during a protocol run.

Issues during calibration process

Pipette calibration failure

The most common issues during pipette calibration are:

• Pipette colliding with the tip probe

• Pipette missing the tip probe

If the pipette is missing the tip probe:

1. Complete a factory reset of pipette offset calibration and retry pipette offset calibration

2. If the issue persists, complete another factory reset of pipette offset calibration and deck calibration and redo deck calibration (make sure you use Opentrons tips for deck calibration). Then retry pipette offset calibration.

3. If the issue persists, contact technical support, let the team know the troubleshooting steps you've tried so far and a video of the failed calibration, and request the next steps.

If the pipette has collided with the tip probe:

1. First visually check all the switches on the tip probe to confirm the switches are in the proper orientation and that they haven't sustained any damage (observe reference images below to determine proper orientation).

2. Complete steps 1-3 above.

Improper orientation:

Proper orientation:

Labware Position Check Failure

The most common issue to occur during the labware position check is a crash. This is a severe issue, as crashing causes corrupt calibration data. If you experience a crash during labware position check, reupload your protocol and restart the labware position check. You should investigate for the following root causes:

• Does the labware definition loaded in the protocol match the physical labware in the slot?

• Did you complete pipette offset calibration?

If you have completed the above and are still having issues, follow these steps in order:

1. Complete a factory reset of pipette offset calibration

2. Complete deck calibration (make sure to use Opentrons tips)

3. Reupload your protocol and retry calibration

If there is a specific labware that the pipette is colliding against during the labware position check, we recommend the following workaround:

1. Before commanding the pipette to move to that particular labware, remove that labware from the deck

2. Command the pipette to move to the empty slot

3. Jog the pipette so there is room to put the labware back in its slot

4. Jog the pipette to position and calibrate as normal

Calibration issues during a run

Troubleshooting Movement Issues

There are many reasons your OT-2 can move erratically during a run. It is important to understand that troubleshooting movement issues like this can require a good deal of upfront investigation to diagnose and resolve. Ultimately, if you are experiencing issues and are troubleshooting (whether independently or with assistance from technical support), it's a best practice to capture images/video of the behavior and clarify the following details:

• What commands in the protocol are being executed at the time of the crash?

• Which pipette is experiencing the crash?

• Which mount is that pipette on?

• Which labware is the pipette crashing against?

• How is this labware loaded in the protocol?

• What is the expected behavior?

Having images/videos of the behavior as well as a strong command of the above details related to your issue will help significantly in the troubleshooting process, especially if you reach out to technical support.

Crashing During a Run

Robot crashing refers to when the robot crashes pipettes into labware or crashes the entire pipette carriage against its own physical boundaries during a run.

The first most common reason for crashing during a run is corrupt calibration data. If you did not complete labware position check or pipette calibration before the run, we suggest you reupload the protocol and complete these calibration processes. Furthermore, ensure that 1) the labware is properly mounted in the slot, and 2) during the calibration process, that there are no collisions, neither between the pipettes and the labware, nor the pipette carriage with its physical boundaries. Rerun the protocol and observe whether the issue persists. If the issue does persist, you may follow these steps for a more exhaustive method of rewriting calibration data:

1. Complete a factory reset of pipette offset calibration

2. Complete a deck calibration

3. Reupload your protocol and complete pipette offset calibration and labware position check

4. Observe whether the erratic behavior persists

The second most common reason for crashing is that the defined labware in the protocol does not match the physical labware on the deck. To verify, you should check your protocol to identify the definition being used, and confirm through our Labware Library that the definition matches the labware on the deck. For instructions on how to use the library, refer to the following article: Using the Labware Library.

Finally, the root cause of the issue may not be that the robot is crashing in error, but that an error in the protocol is commanding the robot to crash against labware or against its physical boundaries. In this case, or if the above troubleshooting did not resolve your issue, contact the support team and we will work to 1) identify whether the crashing issue is reproducible on a robot in our office, and 2) work with you to resolve your issues.

Positional Accuracy

Issues with positional accuracy refer to the pipette's failure to move to the calibrated position in a well during a run. This is a relatively uncommon movement issue, and you should seek assistance from technical support to troubleshoot and resolve these types of issues.

Pipette Drifting

Pipette drifting refers to when a pipette moves further from the center of wells as it iterates through a column/row of a piece of labware.

The two most common root causes for this behavior are mismatched labware definitions and corrupt deck calibration. To investigate the mismatched labware definition issue, you should investigate whether the labware definition loaded in your protocol matches the physical labware on the deck. To troubleshoot deck calibration, you should redo deck calibration, reupload the protocol, redo pipette and labware calibration, and rerun the protocol. If the issue persists, contact technical support at [e-mail].

This Copy is from Opentrons and is Copyrighted, © 2023 Opentrons, it is available at https://support.opentrons.com/ , if you have any questions or concerns just email [e-mail]

⌘J