fix(api): Fix liquid getting homed into pipette after certain protocols end #17285
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| if drop_tips_after_run: | ||
| await self._drop_tip() | ||
| await self._hardware_api.stop(home_after=home_after_stop) | ||
| else: | ||
| await self._hardware_api.stop(home_after=False) | ||
| if home_after_stop: | ||
| await self._home_everything_except_plungers() | ||
| await self._try_to_drop_tips() | ||
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| await self._hardware_api.stop(home_after=False) | ||
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| if home_after_stop: | ||
| await self._home_everything_except_plungers() |
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In the old code:
if drop_tips_after_run:
await self._drop_tip()
await self._hardware_api.stop(home_after=home_after_stop)If home_after_stop was True, the self._hardware_api.stop(...) call would home everything, including the plungers.
I think this used to be safe when this code was originally written. The line immediately preceding it, self._drop_tip(), would have ensured that there were no tips attached, and therefore no liquid for the home to accidentally aspirate.
But that assumption stopped holding for Flex protocols with PAPIv≥2.16; since then, self._drop_tip() has been a no-op (see the comments in _try_to_drop_tips().) So this self._hardware_api.stop(...) was accidentally homing with tips possibly still attached and liquid possibly still in them.
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With my fix here, nothing in this file should ever home the plungers anymore.
We could try to be a little fancier than that. We could home the plungers specifically in the cases where the robot did drop tips. I haven't done that here because it doesn't seem worth the complexity. The plungers will home when the next run begins, anyway.
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Overview
Closes RESC-345.
Test Plan and Hands on Testing
To do.
Changelog
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Review requests
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Risk assessment
Medium.