That‘s an interesting use case! Whenever the lower TADM limit is breached, it is reported as „clot“ error, so that‘s normal. What I don’t understand is that you get a clot error if you run out of liquid. If the tip is drawing in air, that leads to the TADM curve going above the limit, not below. Is it possible that the tip is touching the bottom of the tubes during aspirate following? Edit: just realized you mentioned it‘s fixed height pipetting. That‘s really odd.
Either way, what you could do is custom error handling. There are numerous great threads and examples on this forum, e.g:
In addition, during error handling it is possible to query what is currently in the tip:
This one is awesome as well, there is even a dedicated library „QueryAspiratedVolumes“. Venus : Insufficient Liquid Error
The way this could work is:
- Enable custom errorhandling in the respective „Aspirate“ command. Set it to „Cancel“ for the errors you want to catch. When there is insufficient volume and the error is thrown, the Aspirate will stop immediately, the tip will retract.
- Around the Aspirate step, you need to wrap the error handler command. On error, the aspirate is canceled and the steps you define will be executed.
- In the error handler, you grab the volumes for each tip and decide for each tip what to do. You build „error pipetting sequences“. If the tip holds >280uL you transfer them, in a second sequence you add all the tips with less than 280uL and e.g return that to the source. Notice that your Dispense liquid class will have to be „DrainTip“.
I was digging in that directon before, „Aspirate all“ and „TADM“ don‘t seem to go together.
All the best, Leon