I can currently resolve this problem by adjusting the parameters in the Liquid Class (changing the Blowout volume in Dispense from 8 to 5 or below). However, I would prefer to understand the root cause of this issue. Thank you in advance!
The SubMethod where the error occurred is shown below. It includes one Aspirate and two consecutive Dispense steps. I used two Dispense steps mainly to mix first at a fixed bottom position, then mix again at the liquid surface (I’m not sure if this setup is appropriate?).
Hi. It looks a bit strange. You are aspirating 100ul and dispense 0ul twice?!? Is that correct? What are you trying to accomplish (is it possible to explain this in a little bit more detail)?
The Blowout tip dispense mode is likely the culprit here. It uses sample tracking to dispense what it believes to be in the channels and move the plunger to 0. I believe consecutive blowout tip dispense modes is moving the plunger just out of range (enough that adjusting the blowout slightly keeps it inside the acceptable position). Blowout tip and Drain tip in Jet mode are intended to be the last dispense of the sequence of actions. Example multi-dispense step and then Blowout tip to get eject the remaining liquid in the tip at the end.
Try changing your dispense mode to be (8) From liquid class definition. This will use what the liquid class was defined as the dispense mode. In this case it will use surface empty.
For the first dispense use the same volume that you aspirated (100.0), and on the second dispense use 0. The first dispense will dispense the liquid and perform the mixing at the bottom like normal. The second dispense will not actually dispense anything but will perform the mixing using cLLD.
Hi, I used two Dispense steps mainly to mix first at a fixed bottom position, then mix again at the liquid surface, and I don’t want to add a aspirate step between these 2 dispense steps
Hi, @BrandonBare_Hamilton thanks for your reply. I followed your advice, but the issue still persists. The error only goes away if I set the dispense blowout volume to 5 or lower.
I suspect that the Surface Empty Tip mode also exhausts the blowout air volumn which is set in Liquid Class. As a result, when performing Surface Empty Tip twice consecutively, the plunger is unable to move during the second operation, which triggers the error?
I was able to reproduce the error on my end. The issue definitely is with the blowout. I suspect 8 uL crosses the limit of the extra space that the dispense plunger reserves after dispenses (why 5uL blowout worked). I was able to get around this to fulfill the second mix by using two different techniques:
For the second dispense, change to an aspirate with 0 uL. This will do the pre-mix and then aspirate nothing which should match your top mix goal
Make a second liquid class that has 0 blowout volume and reference that for the second dispense only. You will get a warning that the liquid classes are not the same between aspirate and dispense but it will not throw an error because it isn’t expected to dispense a blowout that doesn’t exist.
