Manually moving channels around#

With PLR, you can easily move individual channels around. This is useful for calibrating labware locations, calibrating labware sizes, and other things.

Warning

Be very careful about collisions! Move channels to a safe z height before traversing.

Note

With Hamilton robots, when a tip is mounted, the z location will refer to the point of the pipetting tip. With no tip mounted, it will refer to the bottom of the channel.

Example: Hamilton STAR#

Here, we’ll use a Hamilton STAR as an example. For other robots, simply change the deck layout, makign sure that you have at least a tip rack to use.

from pylabrobot.liquid_handling import LiquidHandler, STAR
from pylabrobot.resources import STARDeck, TIP_CAR_480_A00, HTF_L

lh = LiquidHandler(backend=STAR(), deck=STARDeck())
await lh.setup()

# assign a tip rack
tip_carrier = TIP_CAR_480_A00(name="tip_carrier")
tip_carrier[0] = tip_rack = HTF_L(name="tip_rack")
lh.deck.assign_child_resource(tip_carrier, rails=0)

Moving channels#

All positions are in mm. The movements are to absolute positions. The origin will be near the left front bottom of the deck, but it differs between robots.

x: left (low) to right (high)
y: front (low) to back (high)
z: bottom (low) to top (high)

channel = 1  # the channel to use

# start by picking up a single tip
await lh.pick_up_tips(tip_rack["A1"], use_channels=[channel])

# prepare for manual operation
# this will space the other channels to safe positions
await lh.prepare_for_manual_channel_operation(channel)

Since the channnel will be above the tip rack, it should be safe to move up. We perform a quick check to make sure the z_safe is at least above the resources we know about.

z_safe = 240  # WARNING: this might NOT be safe for your setup

if z_safe <= lh.deck.get_heighest_known_point():
  raise ValueError(f"z_safe position is not safe, it is lower than the highest known point: {lh.deck.get_heighest_known_point()}")

await lh.move_channel_z(channel, z_safe)

Warning

The z position in the code above should be safe for most setups, but we can’t guarantee that it will be safe for all setups. Move to a z position that is above all your labware before moving in the xy plane.

When the z position of the bottom of the tip is above the labware, you can move the channel around in the xy plane.

# move the channel around
await lh.move_channel_x(channel, 100)
await lh.move_channel_y(channel, 100)

After reaching a spot where the channel can move down, you can use move_channel_z again.

await lh.move_channel_z(channel, 100)

Before returning the tip to the tip rack, make sure to move the channel to a safe z position again.

await lh.move_channel_z(channel, z_safe)

You can run the code above as often as you like. When you’re done, you can return the channel to the tip rack.

await lh.return_tips()