From 48a66324df2ab1c945bab8c07d45ec5fa35e19fd Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Thu, 30 Apr 2026 19:37:19 +0100
Subject: [PATCH 01/21] expose iswap_rotation_drive_move_y

---
 .../backends/hamilton/STAR_backend.py         | 81 +++++++++++++++++++
 1 file changed, 81 insertions(+)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index 7a2dd59ed88..8731015ce56 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -9775,6 +9775,8 @@ async def iswap_request_link_2_length(self) -> float:
   iswap_rotation_drive_min_increment = -30032  # ~ -93 deg
   iswap_rotation_drive_max_increment = 30032  # ~ +93 deg
   iswap_rotation_drive_deg_per_increment = 0.00309619077
+  iswap_rotation_drive_y_speed_increment_range = (50, 8_000)
+  iswap_rotation_drive_diameter = 30.5
 
   class RotationDriveOrientation(enum.Enum):
     LEFT = 1
@@ -9822,6 +9824,85 @@ async def iswap_rotation_drive_request_y(self) -> float:
     iswap_y_pos = resp["ry"][1]  # 0 = FW counter, 1 = HW counter
     return round(STARBackend.y_drive_increment_to_mm(iswap_y_pos), 1)
 
+  async def iswap_rotation_drive_move_y(
+    self,
+    y: float,
+    speed: float = 220.0,
+    acceleration_level: int = 2,
+    current_protection_limiter: int = 7,
+    make_space: bool = False,
+  ):
+    """Move the iSWAP rotation drive to an absolute Y position (R0 YA).
+
+    Args:
+      y: Target Y coordinate in mm.
+      speed: Max velocity in mm/sec. Default 220.0.
+      acceleration_level: Acceleration index, 1 or 2. Default 2.
+      current_protection_limiter: Motor current limit, 0-7. Default 7.
+      make_space: If True, reposition pipetting channels in a single
+        synchronous JY move when channel 0 is in the way and can be cleared.
+        If False, raise so the caller decides.
+    """
+    if not self.extended_conf.left_x_drive.iswap_installed:
+      raise RuntimeError("iSWAP is not installed")
+
+    iswap_radius = STARBackend.iswap_rotation_drive_diameter / 2
+    channel_0_radius = self._channels_minimum_y_spacing[0] / 2
+    channel_0_y = await self.request_y_pos_channel_n(0)
+
+    compressed_channel_0_y = self.extended_conf.left_arm_min_y_position + sum(
+      self._channels_minimum_y_spacing[1:]
+    )
+
+    max_y = self.extended_conf.pip_maximal_y_position
+    absolute_min_y = self.extended_conf.left_arm_min_y_position
+    if not (absolute_min_y <= y <= max_y):
+      raise ValueError(f"y must be between {absolute_min_y} and {max_y} mm, got {y} mm")
+
+    target_channel_0_y = y - channel_0_radius - iswap_radius
+    if channel_0_y > target_channel_0_y:
+      if target_channel_0_y < compressed_channel_0_y:
+        raise ValueError(
+          f"y={y} mm is unreachable: would require channel 0 at "
+          f"{target_channel_0_y} mm, below the compressed floor "
+          f"{compressed_channel_0_y} mm"
+        )
+      if not make_space:
+        raise ValueError(
+          f"y={y} mm requires channel 0 at <= {target_channel_0_y} mm "
+          f"(currently {channel_0_y} mm); pass make_space=True to "
+          f"reposition channels"
+        )
+      await self.move_all_channels_in_z_safety()
+      await self.position_channels_in_y_direction({0: target_channel_0_y}, make_space=True)
+
+    speed_increments = STARBackend.mm_to_y_drive_increment(speed)
+    speed_min, speed_max = STARBackend.iswap_rotation_drive_y_speed_increment_range
+    if not (speed_min <= speed_increments <= speed_max):
+      raise ValueError(
+        f"speed must be between "
+        f"{STARBackend.y_drive_increment_to_mm(speed_min)} and "
+        f"{STARBackend.y_drive_increment_to_mm(speed_max)} mm/sec, "
+        f"got {speed} mm/sec"
+      )
+
+    if not (1 <= acceleration_level <= 2):
+      raise ValueError(f"acceleration_level must be between 1 and 2, got {acceleration_level}")
+
+    if not (0 <= current_protection_limiter <= 7):
+      raise ValueError(
+        f"current_protection_limiter must be between 0 and 7, got {current_protection_limiter}"
+      )
+
+    await self.send_command(
+      module="R0",
+      command="YA",
+      ya=f"{round(STARBackend.mm_to_y_drive_increment(y)):05}",
+      yv=f"{round(speed_increments):04}",
+      yr=f"{int(acceleration_level)}",
+      yw=f"{int(current_protection_limiter)}",
+    )
+
   # Vertical drop from the iSWAP rotation drive plane to the gripper finger
   # plane. R0 RZ is calibrated to the finger plane; the rotation drive sits
   # 13 mm above it.

From 4d121881a8f9139724fffa0060a4d92fc087d171 Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Thu, 30 Apr 2026 19:47:21 +0100
Subject: [PATCH 02/21] shuffle iswap move y next below move x

---
 .../backends/hamilton/STAR_backend.py         | 118 +++++++++---------
 1 file changed, 59 insertions(+), 59 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index a59bb89cad4..70928ec4f9b 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -9871,6 +9871,64 @@ async def iswap_rotation_drive_request_y(self) -> float:
     iswap_y_pos = resp["ry"][1]  # 0 = FW counter, 1 = HW counter
     return round(STARBackend.y_drive_increment_to_mm(iswap_y_pos), 1)
 
+  # Vertical drop from the iSWAP rotation drive plane to the gripper finger
+  # plane. R0 RZ is calibrated to the finger plane; the rotation drive sits
+  # 13 mm above it.
+  iswap_rotation_drive_z_offset_above_finger_mm = 13.0
+
+  async def iswap_rotation_drive_request_z(self) -> float:
+    """Request iSWAP rotation drive Z position (deck coordinates), in mm.
+
+    Adds the 13 mm structural offset to the gripper finger plane (C0 QG).
+    """
+    if not self.extended_conf.left_x_drive.iswap_installed:
+      raise RuntimeError("iSWAP is not installed")
+    finger_plane_z = (await self.request_iswap_position()).z
+    return finger_plane_z + STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
+
+  async def iswap_rotation_drive_request_position(self) -> Coordinate:
+    """Position of the iSWAP rotation drive (joint 1) in deck coordinates, mm."""
+    return Coordinate(
+      x=await self.iswap_rotation_drive_request_x(),
+      y=await self.iswap_rotation_drive_request_y(),
+      z=await self.iswap_rotation_drive_request_z(),
+    )
+
+  async def experimental_iswap_rotation_drive_move_x(
+    self,
+    x: float,
+    acceleration_level: int = 3,
+    current_protection_limiter: int = 7,
+  ):
+    """Move the iSWAP rotation drive to an absolute X position (deck coordinates).
+
+    Thin wrapper around `x_arm_move` that translates rotation-drive X into
+    X-arm carriage X using the cached `kg` offset.
+
+    Args:
+      x: Target rotation-drive X coordinate in mm.
+      acceleration_level: Acceleration index (hardware units), 1-5. Default 3.
+      current_protection_limiter: Motor current limit (hardware units), 0-7. Default 7.
+    """
+    # TODO: remove "experimental_" prefix once x_arm_move has been optimised
+
+    if not self.extended_conf.left_x_drive.iswap_installed:
+      raise RuntimeError("iSWAP is not installed")
+    if self._iswap_rotation_drive_x_offset_mm is None:
+      self._iswap_rotation_drive_x_offset_mm = await self._iswap_rotation_drive_request_x_offset()
+    kg = self._iswap_rotation_drive_x_offset_mm
+
+    x_min = 90.0 - kg
+    x_max = 1350.0 - kg
+    if not (x_min <= x <= x_max):
+      raise ValueError(f"x must be between {x_min} and {x_max} mm, is {x}")
+
+    return await self.experimental_x_arm_move(
+      x=x + kg,
+      acceleration_level=acceleration_level,
+      current_protection_limiter=current_protection_limiter,
+    )
+
   async def iswap_rotation_drive_move_y(
     self,
     y: float,
@@ -9879,7 +9937,7 @@ async def iswap_rotation_drive_move_y(
     current_protection_limiter: int = 7,
     make_space: bool = False,
   ):
-    """Move the iSWAP rotation drive to an absolute Y position (R0 YA).
+    """Move the iSWAP rotation drive to an absolute Y position.
 
     Args:
       y: Target Y coordinate in mm.
@@ -9950,64 +10008,6 @@ async def iswap_rotation_drive_move_y(
       yw=f"{int(current_protection_limiter)}",
     )
 
-  # Vertical drop from the iSWAP rotation drive plane to the gripper finger
-  # plane. R0 RZ is calibrated to the finger plane; the rotation drive sits
-  # 13 mm above it.
-  iswap_rotation_drive_z_offset_above_finger_mm = 13.0
-
-  async def iswap_rotation_drive_request_z(self) -> float:
-    """Request iSWAP rotation drive Z position (deck coordinates), in mm.
-
-    Adds the 13 mm structural offset to the gripper finger plane (C0 QG).
-    """
-    if not self.extended_conf.left_x_drive.iswap_installed:
-      raise RuntimeError("iSWAP is not installed")
-    finger_plane_z = (await self.request_iswap_position()).z
-    return finger_plane_z + STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
-
-  async def iswap_rotation_drive_request_position(self) -> Coordinate:
-    """Position of the iSWAP rotation drive (joint 1) in deck coordinates, mm."""
-    return Coordinate(
-      x=await self.iswap_rotation_drive_request_x(),
-      y=await self.iswap_rotation_drive_request_y(),
-      z=await self.iswap_rotation_drive_request_z(),
-    )
-
-  async def experimental_iswap_rotation_drive_move_x(
-    self,
-    x: float,
-    acceleration_level: int = 3,
-    current_protection_limiter: int = 7,
-  ):
-    """Move the iSWAP rotation drive to an absolute X position (deck coordinates).
-
-    Thin wrapper around `x_arm_move` that translates rotation-drive X into
-    X-arm carriage X using the cached `kg` offset.
-
-    Args:
-      x: Target rotation-drive X coordinate in mm.
-      acceleration_level: Acceleration index (hardware units), 1-5. Default 3.
-      current_protection_limiter: Motor current limit (hardware units), 0-7. Default 7.
-    """
-    # TODO: remove "experimental_" prefix once x_arm_move has been optimised
-
-    if not self.extended_conf.left_x_drive.iswap_installed:
-      raise RuntimeError("iSWAP is not installed")
-    if self._iswap_rotation_drive_x_offset_mm is None:
-      self._iswap_rotation_drive_x_offset_mm = await self._iswap_rotation_drive_request_x_offset()
-    kg = self._iswap_rotation_drive_x_offset_mm
-
-    x_min = 90.0 - kg
-    x_max = 1350.0 - kg
-    if not (x_min <= x <= x_max):
-      raise ValueError(f"x must be between {x_min} and {x_max} mm, is {x}")
-
-    return await self.experimental_x_arm_move(
-      x=x + kg,
-      acceleration_level=acceleration_level,
-      current_protection_limiter=current_protection_limiter,
-    )
-
   async def iswap_rotation_drive_request_predefined_positions(self) -> Dict[str, int]:
     """Read the iSWAP rotation drive (W) predefined-position table from EEPROM.
 

From 561bca4206e6a4dfad4cb29df1b9a7d56eb40a60 Mon Sep 17 00:00:00 2001
From: Rick Wierenga <rick_wierenga@icloud.com>
Date: Thu, 30 Apr 2026 13:02:39 -0700
Subject: [PATCH 03/21] Expose `STARBackend.iswap_rotation_drive_move_z()`

Adds the absolute Z-axis sibling to `iswap_rotation_drive_move_x` (#1018)
and `iswap_rotation_drive_move_y` (#1020). Wraps `R0 ZA` and accepts the
rotation-drive plane Z (matching `iswap_rotation_drive_request_z`); the
13 mm offset to the gripper finger plane is applied internally.
`acceleration` is exposed in mm/sec^2.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 .../backends/hamilton/STAR_backend.py         | 82 +++++++++++++++++++
 1 file changed, 82 insertions(+)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index 70928ec4f9b..9b774aea921 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -9875,6 +9875,14 @@ async def iswap_rotation_drive_request_y(self) -> float:
   # plane. R0 RZ is calibrated to the finger plane; the rotation drive sits
   # 13 mm above it.
   iswap_rotation_drive_z_offset_above_finger_mm = 13.0
+  # R0 ZA firmware spec (SFGT.3112): za=-187..+26661 incr (default 24600),
+  # zv=50..15000 incr/sec (default 11000), zr=5..999 in 1000 incr/sec^2 units
+  # (default 60), zw=0..7 (default 6). Position is in finger-plane coords;
+  # `iswap_rotation_drive_move_z` adds the 13 mm offset for the user.
+  iswap_rotation_drive_z_min_increment = -187
+  iswap_rotation_drive_z_max_increment = 26_661
+  iswap_rotation_drive_z_speed_increment_range = (50, 15_000)
+  iswap_rotation_drive_z_acceleration_increment_range = (5, 999)
 
   async def iswap_rotation_drive_request_z(self) -> float:
     """Request iSWAP rotation drive Z position (deck coordinates), in mm.
@@ -10008,6 +10016,80 @@ async def iswap_rotation_drive_move_y(
       yw=f"{int(current_protection_limiter)}",
     )
 
+  async def iswap_rotation_drive_move_z(
+    self,
+    z: float,
+    speed: float = 118.0,
+    acceleration: float = 643.66,
+    current_protection_limiter: int = 6,
+  ):
+    """Move the iSWAP rotation drive to an absolute Z position (deck coordinates).
+
+    `z` is the rotation-drive plane Z, matching what
+    `iswap_rotation_drive_request_z` returns. The 13 mm offset to the gripper
+    finger plane (where R0 ZA is calibrated) is applied internally.
+
+    Args:
+      z: Target rotation-drive Z coordinate in mm.
+      speed: Max velocity in mm/sec. Default 118.0 (firmware default).
+      acceleration: Acceleration in mm/sec^2. Default 643.66
+        (firmware default 60 in 1000 incr/sec^2 units).
+      current_protection_limiter: Motor current limit, 0-7. Default 6
+        (firmware default).
+    """
+    if not self.extended_conf.left_x_drive.iswap_installed:
+      raise RuntimeError("iSWAP is not installed")
+
+    z_min_incr = STARBackend.iswap_rotation_drive_z_min_increment
+    z_max_incr = STARBackend.iswap_rotation_drive_z_max_increment
+    absolute_min_z = (
+      STARBackend.z_drive_increment_to_mm(z_min_incr)
+      + STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
+    )
+    absolute_max_z = (
+      STARBackend.z_drive_increment_to_mm(z_max_incr)
+      + STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
+    )
+    if not (absolute_min_z <= z <= absolute_max_z):
+      raise ValueError(f"z must be between {absolute_min_z} and {absolute_max_z} mm, got {z} mm")
+
+    finger_plane_z = z - STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
+    z_increments = STARBackend.mm_to_z_drive_increment(finger_plane_z)
+
+    speed_increments = STARBackend.mm_to_z_drive_increment(speed)
+    speed_min, speed_max = STARBackend.iswap_rotation_drive_z_speed_increment_range
+    if not (speed_min <= speed_increments <= speed_max):
+      raise ValueError(
+        f"speed must be between "
+        f"{STARBackend.z_drive_increment_to_mm(speed_min)} and "
+        f"{STARBackend.z_drive_increment_to_mm(speed_max)} mm/sec, "
+        f"got {speed} mm/sec"
+      )
+
+    acceleration_increments = STARBackend.mm_to_z_drive_increment(acceleration / 1000)
+    accel_min, accel_max = STARBackend.iswap_rotation_drive_z_acceleration_increment_range
+    if not (accel_min <= acceleration_increments <= accel_max):
+      raise ValueError(
+        f"acceleration must be between "
+        f"{STARBackend.z_drive_increment_to_mm(accel_min * 1000)} and "
+        f"{STARBackend.z_drive_increment_to_mm(accel_max * 1000)} mm/sec^2, "
+        f"got {acceleration} mm/sec^2"
+      )
+
+    if not (0 <= current_protection_limiter <= 7):
+      raise ValueError(
+        f"current_protection_limiter must be between 0 and 7, got {current_protection_limiter}"
+      )
+
+    await self.send_command(
+      module="R0",
+      command="ZA",
+      za=f"{round(z_increments):+06}",
+      zv=f"{round(speed_increments):05}",
+      zr=f"{round(acceleration_increments):03}",
+      zw=f"{int(current_protection_limiter)}",
+    )
+
   async def iswap_rotation_drive_request_predefined_positions(self) -> Dict[str, int]:
     """Read the iSWAP rotation drive (W) predefined-position table from EEPROM.
 

From f6f9bda38adccbec404c895cecae9d3f51cb4354 Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 13:39:01 +0100
Subject: [PATCH 04/21] clarify `bottom` return (per LFB PLR expectation)

PLR users expect left-front-bottom referencing;

for channels this changes to center-center in x-y but in z people still expect bottom;

since we are referencing the actual rotation drive here and its bottom is 13 mm above the finger_z_plane I have added a short comment to make this clearer
---
 .../liquid_handling/backends/hamilton/STAR_backend.py      | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index 6f3b1e60833..5d2519756b4 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -9876,10 +9876,9 @@ async def iswap_rotation_drive_request_y(self) -> float:
   # plane. R0 RZ is calibrated to the finger plane; the rotation drive sits
   # 13 mm above it.
   iswap_rotation_drive_z_offset_above_finger_mm = 13.0
-  # R0 ZA firmware spec (SFGT.3112): za=-187..+26661 incr (default 24600),
-  # zv=50..15000 incr/sec (default 11000), zr=5..999 in 1000 incr/sec^2 units
-  # (default 60), zw=0..7 (default 6). Position is in finger-plane coords;
-  # `iswap_rotation_drive_move_z` adds the 13 mm offset for the user.
+  
+  # Position is in finger-plane coords; `iswap_rotation_drive_move_z` adds
+  # the 13 mm offset to return the bottom position of the rotation drive.
   iswap_rotation_drive_z_min_increment = -187
   iswap_rotation_drive_z_max_increment = 26_661
   iswap_rotation_drive_z_speed_increment_range = (50, 15_000)

From a1b6e381c1356a63aeaddf19cc9f4e5309394094 Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 13:40:26 +0100
Subject: [PATCH 05/21] `make format`

---
 pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index 5d2519756b4..fca96c26d34 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -9876,7 +9876,7 @@ async def iswap_rotation_drive_request_y(self) -> float:
   # plane. R0 RZ is calibrated to the finger plane; the rotation drive sits
   # 13 mm above it.
   iswap_rotation_drive_z_offset_above_finger_mm = 13.0
-  
+
   # Position is in finger-plane coords; `iswap_rotation_drive_move_z` adds
   # the 13 mm offset to return the bottom position of the rotation drive.
   iswap_rotation_drive_z_min_increment = -187

From c91052476b8edbabea50d205e4e99bdf846c0957 Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 13:47:58 +0100
Subject: [PATCH 06/21] create
 `iswap_rotation_drive_request_predefined_z_positions`

---
 .../backends/hamilton/STAR_backend.py         | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index fca96c26d34..f94ab8d7e8a 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -10098,6 +10098,45 @@ async def iswap_rotation_drive_move_z(
       zw=f"{int(current_protection_limiter)}",
     )
 
+  async def iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str, int]:
+    """Read the iSWAP rotation-drive Z-axis predefined-position table from EEPROM.
+
+    Sends R0 RA ra=pz. Firmware returns 10 signed-integer slots; all 10 are
+    positions (no length slot, unlike pw/pt). Slots beyond home/parking are
+    extra slots addressable via R0 ZP zp2..zp9.
+
+    Keys (motor increments; Z-drive resolution 0.01072765 mm/incr):
+      "home"     pz[0]  - home position
+      "parking"  pz[1]  - parking pose (firmware requires pz[1] >= iz + 100)
+      "extra_1"  pz[2]  - extra slot, address via R0 ZP zp2
+      "extra_2"  pz[3]  - extra slot, address via R0 ZP zp3
+      "extra_3"  pz[4]  - extra slot, address via R0 ZP zp4
+      "extra_4"  pz[5]  - extra slot, address via R0 ZP zp5
+      "extra_5"  pz[6]  - extra slot, address via R0 ZP zp6
+      "extra_6"  pz[7]  - extra slot, address via R0 ZP zp7
+      "extra_7"  pz[8]  - extra slot, address via R0 ZP zp8
+      "extra_8"  pz[9]  - extra slot, address via R0 ZP zp9
+
+    Raises:
+      RuntimeError: if the iSWAP module is not installed.
+    """
+    if not self.extended_conf.left_x_drive.iswap_installed:
+      raise RuntimeError("iSWAP is not installed")
+    resp = await self.send_command(module="R0", command="RA", ra="pz", fmt="pz##### (n)")
+    pz = cast(List[int], resp["pz"])
+    return {
+      "home": pz[0],
+      "parking": pz[1],
+      "extra_1": pz[2],
+      "extra_2": pz[3],
+      "extra_3": pz[4],
+      "extra_4": pz[5],
+      "extra_5": pz[6],
+      "extra_6": pz[7],
+      "extra_7": pz[8],
+      "extra_8": pz[9],
+    }
+
   async def iswap_rotation_drive_request_predefined_positions(self) -> Dict[str, int]:
     """Read the iSWAP rotation drive (W) predefined-position table from EEPROM.
 

From b9cab7d8f19f2011ad5adba3d5315910c3e3084f Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 13:55:20 +0100
Subject: [PATCH 07/21] create
 `iswap_rotation_drive_request_predefined_y_positions`

---
 .../backends/hamilton/STAR_backend.py         | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index f94ab8d7e8a..ef13644079e 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -10024,6 +10024,45 @@ async def iswap_rotation_drive_move_y(
       yw=f"{int(current_protection_limiter)}",
     )
 
+  async def iswap_rotation_drive_request_predefined_y_positions(self) -> Dict[str, int]:
+    """Read the iSWAP rotation-drive Y-axis predefined-position table from EEPROM.
+
+    Sends R0 RA ra=py. Firmware returns 10 signed-integer slots; all 10 are
+    positions (no length slot, unlike pw/pt). Slots beyond the documented
+    semantic roles are extra slots addressable via R0 YP yp5..yp9.
+
+    Keys (motor increments; Y-drive resolution 0.046302 mm/incr):
+      "home"         py[0]  - home position
+      "lower_limit"  py[1]  - lower travel limit
+      "upper_limit"  py[2]  - upper travel limit
+      "parking"      py[3]  - parking pose (firmware requires py[3] > iy + 100)
+      "pre_parking"  py[4]  - pre-parking pose (firmware requires py[4] < py[3] - 430)
+      "extra_1"      py[5]  - extra slot, address via R0 YP yp5
+      "extra_2"      py[6]  - extra slot, address via R0 YP yp6
+      "extra_3"      py[7]  - extra slot, address via R0 YP yp7
+      "extra_4"      py[8]  - extra slot, address via R0 YP yp8
+      "extra_5"      py[9]  - extra slot, address via R0 YP yp9
+
+    Raises:
+      RuntimeError: if the iSWAP module is not installed.
+    """
+    if not self.extended_conf.left_x_drive.iswap_installed:
+      raise RuntimeError("iSWAP is not installed")
+    resp = await self.send_command(module="R0", command="RA", ra="py", fmt="py##### (n)")
+    py = cast(List[int], resp["py"])
+    return {
+      "home": py[0],
+      "lower_limit": py[1],
+      "upper_limit": py[2],
+      "parking": py[3],
+      "pre_parking": py[4],
+      "extra_1": py[5],
+      "extra_2": py[6],
+      "extra_3": py[7],
+      "extra_4": py[8],
+      "extra_5": py[9],
+    }
+
   async def iswap_rotation_drive_move_z(
     self,
     z: float,

From 861044024da71f643f8eaf0df19d16256a340c7d Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 14:48:50 +0100
Subject: [PATCH 08/21] add iSWAP Y/Z drive conversions and correct pip Y
 resolution

---
 .../backends/hamilton/STAR_backend.py         | 21 ++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index ef13644079e..d11fa10d5f4 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -9826,6 +9826,25 @@ async def iswap_request_link_2_length(self) -> float:
   iswap_rotation_drive_diameter = 30.5
   iswap_rotation_drive_safety_radius = 90.0
 
+  iswap_y_drive_mm_per_increment = 0.046302083
+  iswap_z_drive_mm_per_increment = 0.01072765
+
+  @staticmethod
+  def iswap_y_drive_mm_to_increment(value_mm: float) -> int:
+    return round(value_mm / STARBackend.iswap_y_drive_mm_per_increment)
+
+  @staticmethod
+  def iswap_y_drive_increment_to_mm(value_increments: int) -> float:
+    return round(value_increments * STARBackend.iswap_y_drive_mm_per_increment, 2)
+
+  @staticmethod
+  def iswap_z_drive_mm_to_increment(value_mm: float) -> int:
+    return round(value_mm / STARBackend.iswap_z_drive_mm_per_increment)
+
+  @staticmethod
+  def iswap_z_drive_increment_to_mm(value_increments: int) -> float:
+    return round(value_increments * STARBackend.iswap_z_drive_mm_per_increment, 2)
+
   class RotationDriveOrientation(enum.Enum):
     LEFT = 1
     FRONT = 2
@@ -11235,7 +11254,7 @@ async def request_cover_open(self) -> bool:
 
   # -------------- Extra - Probing labware with STAR - making STAR into a CMM --------------
 
-  y_drive_mm_per_increment = 0.046302082
+  y_drive_mm_per_increment = 0.046302083
   z_drive_mm_per_increment = 0.01072765
 
   dispensing_drive_vol_per_increment = 0.046876  # uL / increment

From de21aa6f2cee5c771699775d30d7a00dd60a2d41 Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 15:20:16 +0100
Subject: [PATCH 09/21] tighten iswap_rotation_drive_move_z error messages and
 document Raises

---
 .../backends/hamilton/STAR_backend.py             | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index d11fa10d5f4..4ad95819f8a 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -10050,7 +10050,7 @@ async def iswap_rotation_drive_request_predefined_y_positions(self) -> Dict[str,
     positions (no length slot, unlike pw/pt). Slots beyond the documented
     semantic roles are extra slots addressable via R0 YP yp5..yp9.
 
-    Keys (motor increments; Y-drive resolution 0.046302 mm/incr):
+    Keys (motor increments; see `iswap_y_drive_mm_per_increment`):
       "home"         py[0]  - home position
       "lower_limit"  py[1]  - lower travel limit
       "upper_limit"  py[2]  - upper travel limit
@@ -10102,6 +10102,9 @@ async def iswap_rotation_drive_move_z(
         (firmware default 60 in 1000 incr/sec^2 units).
       current_protection_limiter: Motor current limit, 0-7. Default 6
         (firmware default).
+
+    Raises:
+      RuntimeError: if the iSWAP module is not installed.
     """
     if not self.extended_conf.left_x_drive.iswap_installed:
       raise RuntimeError("iSWAP is not installed")
@@ -10117,7 +10120,7 @@ async def iswap_rotation_drive_move_z(
       + STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
     )
     if not (absolute_min_z <= z <= absolute_max_z):
-      raise ValueError(f"z must be between {absolute_min_z} and {absolute_max_z} mm, got {z} mm")
+      raise ValueError(f"z must be between {absolute_min_z} and {absolute_max_z} mm, is {z}")
 
     finger_plane_z = z - STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
     z_increments = STARBackend.mm_to_z_drive_increment(finger_plane_z)
@@ -10129,7 +10132,7 @@ async def iswap_rotation_drive_move_z(
         f"speed must be between "
         f"{STARBackend.z_drive_increment_to_mm(speed_min)} and "
         f"{STARBackend.z_drive_increment_to_mm(speed_max)} mm/sec, "
-        f"got {speed} mm/sec"
+        f"is {speed}"
       )
 
     acceleration_increments = STARBackend.mm_to_z_drive_increment(acceleration / 1000)
@@ -10139,12 +10142,12 @@ async def iswap_rotation_drive_move_z(
         f"acceleration must be between "
         f"{STARBackend.z_drive_increment_to_mm(accel_min * 1000)} and "
         f"{STARBackend.z_drive_increment_to_mm(accel_max * 1000)} mm/sec^2, "
-        f"got {acceleration} mm/sec^2"
+        f"is {acceleration}"
       )
 
     if not (0 <= current_protection_limiter <= 7):
       raise ValueError(
-        f"current_protection_limiter must be between 0 and 7, got {current_protection_limiter}"
+        f"current_protection_limiter must be between 0 and 7, is {current_protection_limiter}"
       )
 
     await self.send_command(
@@ -10163,7 +10166,7 @@ async def iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str,
     positions (no length slot, unlike pw/pt). Slots beyond home/parking are
     extra slots addressable via R0 ZP zp2..zp9.
 
-    Keys (motor increments; Z-drive resolution 0.01072765 mm/incr):
+    Keys (motor increments; see `iswap_z_drive_mm_per_increment`):
       "home"     pz[0]  - home position
       "parking"  pz[1]  - parking pose (firmware requires pz[1] >= iz + 100)
       "extra_1"  pz[2]  - extra slot, address via R0 ZP zp2

From 414aec5aa28b0c21cf94dcfb003ca26ed03a9d7a Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 13:47:58 +0100
Subject: [PATCH 10/21] create
 `iswap_rotation_drive_request_predefined_z_positions`

---
 .../backends/hamilton/STAR_backend.py         | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index fca96c26d34..f94ab8d7e8a 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -10098,6 +10098,45 @@ async def iswap_rotation_drive_move_z(
       zw=f"{int(current_protection_limiter)}",
     )
 
+  async def iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str, int]:
+    """Read the iSWAP rotation-drive Z-axis predefined-position table from EEPROM.
+
+    Sends R0 RA ra=pz. Firmware returns 10 signed-integer slots; all 10 are
+    positions (no length slot, unlike pw/pt). Slots beyond home/parking are
+    extra slots addressable via R0 ZP zp2..zp9.
+
+    Keys (motor increments; Z-drive resolution 0.01072765 mm/incr):
+      "home"     pz[0]  - home position
+      "parking"  pz[1]  - parking pose (firmware requires pz[1] >= iz + 100)
+      "extra_1"  pz[2]  - extra slot, address via R0 ZP zp2
+      "extra_2"  pz[3]  - extra slot, address via R0 ZP zp3
+      "extra_3"  pz[4]  - extra slot, address via R0 ZP zp4
+      "extra_4"  pz[5]  - extra slot, address via R0 ZP zp5
+      "extra_5"  pz[6]  - extra slot, address via R0 ZP zp6
+      "extra_6"  pz[7]  - extra slot, address via R0 ZP zp7
+      "extra_7"  pz[8]  - extra slot, address via R0 ZP zp8
+      "extra_8"  pz[9]  - extra slot, address via R0 ZP zp9
+
+    Raises:
+      RuntimeError: if the iSWAP module is not installed.
+    """
+    if not self.extended_conf.left_x_drive.iswap_installed:
+      raise RuntimeError("iSWAP is not installed")
+    resp = await self.send_command(module="R0", command="RA", ra="pz", fmt="pz##### (n)")
+    pz = cast(List[int], resp["pz"])
+    return {
+      "home": pz[0],
+      "parking": pz[1],
+      "extra_1": pz[2],
+      "extra_2": pz[3],
+      "extra_3": pz[4],
+      "extra_4": pz[5],
+      "extra_5": pz[6],
+      "extra_6": pz[7],
+      "extra_7": pz[8],
+      "extra_8": pz[9],
+    }
+
   async def iswap_rotation_drive_request_predefined_positions(self) -> Dict[str, int]:
     """Read the iSWAP rotation drive (W) predefined-position table from EEPROM.
 

From be4ceb4efba1abc39c5480619484ca8c5adc252e Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 13:55:20 +0100
Subject: [PATCH 11/21] create
 `iswap_rotation_drive_request_predefined_y_positions`

---
 .../backends/hamilton/STAR_backend.py         | 39 +++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index f94ab8d7e8a..ef13644079e 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -10024,6 +10024,45 @@ async def iswap_rotation_drive_move_y(
       yw=f"{int(current_protection_limiter)}",
     )
 
+  async def iswap_rotation_drive_request_predefined_y_positions(self) -> Dict[str, int]:
+    """Read the iSWAP rotation-drive Y-axis predefined-position table from EEPROM.
+
+    Sends R0 RA ra=py. Firmware returns 10 signed-integer slots; all 10 are
+    positions (no length slot, unlike pw/pt). Slots beyond the documented
+    semantic roles are extra slots addressable via R0 YP yp5..yp9.
+
+    Keys (motor increments; Y-drive resolution 0.046302 mm/incr):
+      "home"         py[0]  - home position
+      "lower_limit"  py[1]  - lower travel limit
+      "upper_limit"  py[2]  - upper travel limit
+      "parking"      py[3]  - parking pose (firmware requires py[3] > iy + 100)
+      "pre_parking"  py[4]  - pre-parking pose (firmware requires py[4] < py[3] - 430)
+      "extra_1"      py[5]  - extra slot, address via R0 YP yp5
+      "extra_2"      py[6]  - extra slot, address via R0 YP yp6
+      "extra_3"      py[7]  - extra slot, address via R0 YP yp7
+      "extra_4"      py[8]  - extra slot, address via R0 YP yp8
+      "extra_5"      py[9]  - extra slot, address via R0 YP yp9
+
+    Raises:
+      RuntimeError: if the iSWAP module is not installed.
+    """
+    if not self.extended_conf.left_x_drive.iswap_installed:
+      raise RuntimeError("iSWAP is not installed")
+    resp = await self.send_command(module="R0", command="RA", ra="py", fmt="py##### (n)")
+    py = cast(List[int], resp["py"])
+    return {
+      "home": py[0],
+      "lower_limit": py[1],
+      "upper_limit": py[2],
+      "parking": py[3],
+      "pre_parking": py[4],
+      "extra_1": py[5],
+      "extra_2": py[6],
+      "extra_3": py[7],
+      "extra_4": py[8],
+      "extra_5": py[9],
+    }
+
   async def iswap_rotation_drive_move_z(
     self,
     z: float,

From 70de9fb67830e1524c08e2522808e581af633c87 Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 14:48:50 +0100
Subject: [PATCH 12/21] add iSWAP Y/Z drive conversions and correct pip Y
 resolution

---
 .../backends/hamilton/STAR_backend.py         | 21 ++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index ef13644079e..d11fa10d5f4 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -9826,6 +9826,25 @@ async def iswap_request_link_2_length(self) -> float:
   iswap_rotation_drive_diameter = 30.5
   iswap_rotation_drive_safety_radius = 90.0
 
+  iswap_y_drive_mm_per_increment = 0.046302083
+  iswap_z_drive_mm_per_increment = 0.01072765
+
+  @staticmethod
+  def iswap_y_drive_mm_to_increment(value_mm: float) -> int:
+    return round(value_mm / STARBackend.iswap_y_drive_mm_per_increment)
+
+  @staticmethod
+  def iswap_y_drive_increment_to_mm(value_increments: int) -> float:
+    return round(value_increments * STARBackend.iswap_y_drive_mm_per_increment, 2)
+
+  @staticmethod
+  def iswap_z_drive_mm_to_increment(value_mm: float) -> int:
+    return round(value_mm / STARBackend.iswap_z_drive_mm_per_increment)
+
+  @staticmethod
+  def iswap_z_drive_increment_to_mm(value_increments: int) -> float:
+    return round(value_increments * STARBackend.iswap_z_drive_mm_per_increment, 2)
+
   class RotationDriveOrientation(enum.Enum):
     LEFT = 1
     FRONT = 2
@@ -11235,7 +11254,7 @@ async def request_cover_open(self) -> bool:
 
   # -------------- Extra - Probing labware with STAR - making STAR into a CMM --------------
 
-  y_drive_mm_per_increment = 0.046302082
+  y_drive_mm_per_increment = 0.046302083
   z_drive_mm_per_increment = 0.01072765
 
   dispensing_drive_vol_per_increment = 0.046876  # uL / increment

From 3a90a19df77dd13badc634dbc2e9f297d39b1a77 Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 15:20:16 +0100
Subject: [PATCH 13/21] tighten iswap_rotation_drive_move_z error messages and
 document Raises

---
 .../backends/hamilton/STAR_backend.py             | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index d11fa10d5f4..4ad95819f8a 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -10050,7 +10050,7 @@ async def iswap_rotation_drive_request_predefined_y_positions(self) -> Dict[str,
     positions (no length slot, unlike pw/pt). Slots beyond the documented
     semantic roles are extra slots addressable via R0 YP yp5..yp9.
 
-    Keys (motor increments; Y-drive resolution 0.046302 mm/incr):
+    Keys (motor increments; see `iswap_y_drive_mm_per_increment`):
       "home"         py[0]  - home position
       "lower_limit"  py[1]  - lower travel limit
       "upper_limit"  py[2]  - upper travel limit
@@ -10102,6 +10102,9 @@ async def iswap_rotation_drive_move_z(
         (firmware default 60 in 1000 incr/sec^2 units).
       current_protection_limiter: Motor current limit, 0-7. Default 6
         (firmware default).
+
+    Raises:
+      RuntimeError: if the iSWAP module is not installed.
     """
     if not self.extended_conf.left_x_drive.iswap_installed:
       raise RuntimeError("iSWAP is not installed")
@@ -10117,7 +10120,7 @@ async def iswap_rotation_drive_move_z(
       + STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
     )
     if not (absolute_min_z <= z <= absolute_max_z):
-      raise ValueError(f"z must be between {absolute_min_z} and {absolute_max_z} mm, got {z} mm")
+      raise ValueError(f"z must be between {absolute_min_z} and {absolute_max_z} mm, is {z}")
 
     finger_plane_z = z - STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
     z_increments = STARBackend.mm_to_z_drive_increment(finger_plane_z)
@@ -10129,7 +10132,7 @@ async def iswap_rotation_drive_move_z(
         f"speed must be between "
         f"{STARBackend.z_drive_increment_to_mm(speed_min)} and "
         f"{STARBackend.z_drive_increment_to_mm(speed_max)} mm/sec, "
-        f"got {speed} mm/sec"
+        f"is {speed}"
       )
 
     acceleration_increments = STARBackend.mm_to_z_drive_increment(acceleration / 1000)
@@ -10139,12 +10142,12 @@ async def iswap_rotation_drive_move_z(
         f"acceleration must be between "
         f"{STARBackend.z_drive_increment_to_mm(accel_min * 1000)} and "
         f"{STARBackend.z_drive_increment_to_mm(accel_max * 1000)} mm/sec^2, "
-        f"got {acceleration} mm/sec^2"
+        f"is {acceleration}"
       )
 
     if not (0 <= current_protection_limiter <= 7):
       raise ValueError(
-        f"current_protection_limiter must be between 0 and 7, got {current_protection_limiter}"
+        f"current_protection_limiter must be between 0 and 7, is {current_protection_limiter}"
       )
 
     await self.send_command(
@@ -10163,7 +10166,7 @@ async def iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str,
     positions (no length slot, unlike pw/pt). Slots beyond home/parking are
     extra slots addressable via R0 ZP zp2..zp9.
 
-    Keys (motor increments; Z-drive resolution 0.01072765 mm/incr):
+    Keys (motor increments; see `iswap_z_drive_mm_per_increment`):
       "home"     pz[0]  - home position
       "parking"  pz[1]  - parking pose (firmware requires pz[1] >= iz + 100)
       "extra_1"  pz[2]  - extra slot, address via R0 ZP zp2

From da985da4fcd202653ecad88128c967f974be9d05 Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 15:48:21 +0100
Subject: [PATCH 14/21] drop firmware-internal constraints from predefined Y/Z
 parking-pose docstrings

---
 pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index 4ad95819f8a..c0b57f3e567 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -10054,7 +10054,7 @@ async def iswap_rotation_drive_request_predefined_y_positions(self) -> Dict[str,
       "home"         py[0]  - home position
       "lower_limit"  py[1]  - lower travel limit
       "upper_limit"  py[2]  - upper travel limit
-      "parking"      py[3]  - parking pose (firmware requires py[3] > iy + 100)
+      "parking"      py[3]  - parking pose (back of travel)
       "pre_parking"  py[4]  - pre-parking pose (firmware requires py[4] < py[3] - 430)
       "extra_1"      py[5]  - extra slot, address via R0 YP yp5
       "extra_2"      py[6]  - extra slot, address via R0 YP yp6
@@ -10168,7 +10168,7 @@ async def iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str,
 
     Keys (motor increments; see `iswap_z_drive_mm_per_increment`):
       "home"     pz[0]  - home position
-      "parking"  pz[1]  - parking pose (firmware requires pz[1] >= iz + 100)
+      "parking"  pz[1]  - parking pose (top of travel)
       "extra_1"  pz[2]  - extra slot, address via R0 ZP zp2
       "extra_2"  pz[3]  - extra slot, address via R0 ZP zp3
       "extra_3"  pz[4]  - extra slot, address via R0 ZP zp4

From 5250402bdd252d5411b6a96da1206702d561ba2e Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 15:56:30 +0100
Subject: [PATCH 15/21] reword Z increment-range comment to drop misleading
 return claim

---
 pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index c0b57f3e567..dd76f376d30 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -9896,8 +9896,9 @@ async def iswap_rotation_drive_request_y(self) -> float:
   # 13 mm above it.
   iswap_rotation_drive_z_offset_above_finger_mm = 13.0
 
-  # Position is in finger-plane coords; `iswap_rotation_drive_move_z` adds
-  # the 13 mm offset to return the bottom position of the rotation drive.
+  # Z increment ranges below are in finger-plane coords (the R0 ZA reference).
+  # `iswap_rotation_drive_move_z` and `iswap_rotation_drive_request_z` apply
+  # the 13 mm offset internally to translate between deck and finger-plane Z.
   iswap_rotation_drive_z_min_increment = -187
   iswap_rotation_drive_z_max_increment = 26_661
   iswap_rotation_drive_z_speed_increment_range = (50, 15_000)

From e648668bfa2690bf08502a64dbdbc717a742be59 Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 16:14:08 +0100
Subject: [PATCH 16/21] decouple iSWAP rotation-drive Y/Z from PIP-channel
 conversions

---
 .../backends/hamilton/STAR_backend.py         | 28 +++++++++----------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index dd76f376d30..56987a54418 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -9889,7 +9889,7 @@ async def iswap_rotation_drive_request_y(self) -> float:
       raise RuntimeError("iSWAP is not installed")
     resp = await self.send_command(module="R0", command="RY", fmt="ry##### (n)")
     iswap_y_pos = resp["ry"][1]  # 0 = FW counter, 1 = HW counter
-    return round(STARBackend.y_drive_increment_to_mm(iswap_y_pos), 1)
+    return round(STARBackend.iswap_y_drive_increment_to_mm(iswap_y_pos), 1)
 
   # Vertical drop from the iSWAP rotation drive plane to the gripper finger
   # plane. R0 RZ is calibrated to the finger plane; the rotation drive sits
@@ -10017,13 +10017,13 @@ async def iswap_rotation_drive_move_y(
       await self.move_all_channels_in_z_safety()
       await self.position_channels_in_y_direction({0: target_channel_0_y}, make_space=True)
 
-    speed_increments = STARBackend.mm_to_y_drive_increment(speed)
+    speed_increments = STARBackend.iswap_y_drive_mm_to_increment(speed)
     speed_min, speed_max = STARBackend.iswap_rotation_drive_y_speed_increment_range
     if not (speed_min <= speed_increments <= speed_max):
       raise ValueError(
         f"speed must be between "
-        f"{STARBackend.y_drive_increment_to_mm(speed_min)} and "
-        f"{STARBackend.y_drive_increment_to_mm(speed_max)} mm/sec, "
+        f"{STARBackend.iswap_y_drive_increment_to_mm(speed_min)} and "
+        f"{STARBackend.iswap_y_drive_increment_to_mm(speed_max)} mm/sec, "
         f"got {speed} mm/sec"
       )
 
@@ -10038,7 +10038,7 @@ async def iswap_rotation_drive_move_y(
     await self.send_command(
       module="R0",
       command="YA",
-      ya=f"{round(STARBackend.mm_to_y_drive_increment(y)):05}",
+      ya=f"{round(STARBackend.iswap_y_drive_mm_to_increment(y)):05}",
       yv=f"{round(speed_increments):04}",
       yr=f"{int(acceleration_level)}",
       yw=f"{int(current_protection_limiter)}",
@@ -10113,36 +10113,36 @@ async def iswap_rotation_drive_move_z(
     z_min_incr = STARBackend.iswap_rotation_drive_z_min_increment
     z_max_incr = STARBackend.iswap_rotation_drive_z_max_increment
     absolute_min_z = (
-      STARBackend.z_drive_increment_to_mm(z_min_incr)
+      STARBackend.iswap_z_drive_increment_to_mm(z_min_incr)
       + STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
     )
     absolute_max_z = (
-      STARBackend.z_drive_increment_to_mm(z_max_incr)
+      STARBackend.iswap_z_drive_increment_to_mm(z_max_incr)
       + STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
     )
     if not (absolute_min_z <= z <= absolute_max_z):
       raise ValueError(f"z must be between {absolute_min_z} and {absolute_max_z} mm, is {z}")
 
     finger_plane_z = z - STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
-    z_increments = STARBackend.mm_to_z_drive_increment(finger_plane_z)
+    z_increments = STARBackend.iswap_z_drive_mm_to_increment(finger_plane_z)
 
-    speed_increments = STARBackend.mm_to_z_drive_increment(speed)
+    speed_increments = STARBackend.iswap_z_drive_mm_to_increment(speed)
     speed_min, speed_max = STARBackend.iswap_rotation_drive_z_speed_increment_range
     if not (speed_min <= speed_increments <= speed_max):
       raise ValueError(
         f"speed must be between "
-        f"{STARBackend.z_drive_increment_to_mm(speed_min)} and "
-        f"{STARBackend.z_drive_increment_to_mm(speed_max)} mm/sec, "
+        f"{STARBackend.iswap_z_drive_increment_to_mm(speed_min)} and "
+        f"{STARBackend.iswap_z_drive_increment_to_mm(speed_max)} mm/sec, "
         f"is {speed}"
       )
 
-    acceleration_increments = STARBackend.mm_to_z_drive_increment(acceleration / 1000)
+    acceleration_increments = STARBackend.iswap_z_drive_mm_to_increment(acceleration / 1000)
     accel_min, accel_max = STARBackend.iswap_rotation_drive_z_acceleration_increment_range
     if not (accel_min <= acceleration_increments <= accel_max):
       raise ValueError(
         f"acceleration must be between "
-        f"{STARBackend.z_drive_increment_to_mm(accel_min * 1000)} and "
-        f"{STARBackend.z_drive_increment_to_mm(accel_max * 1000)} mm/sec^2, "
+        f"{STARBackend.iswap_z_drive_increment_to_mm(accel_min * 1000)} and "
+        f"{STARBackend.iswap_z_drive_increment_to_mm(accel_max * 1000)} mm/sec^2, "
         f"is {acceleration}"
       )
 

From e8c2d7d28e2cac675ce15ba8cee050a8cb8e42d4 Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 18:01:05 +0100
Subject: [PATCH 17/21] rename increment version to `_` and provide public API
 in expected mm

---
 .../backends/hamilton/STAR_backend.py         | 28 +++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index 56987a54418..99700a6eee0 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -10044,7 +10044,7 @@ async def iswap_rotation_drive_move_y(
       yw=f"{int(current_protection_limiter)}",
     )
 
-  async def iswap_rotation_drive_request_predefined_y_positions(self) -> Dict[str, int]:
+  async def _iswap_rotation_drive_request_predefined_y_positions(self) -> Dict[str, int]:
     """Read the iSWAP rotation-drive Y-axis predefined-position table from EEPROM.
 
     Sends R0 RA ra=py. Firmware returns 10 signed-integer slots; all 10 are
@@ -10083,6 +10083,18 @@ async def iswap_rotation_drive_request_predefined_y_positions(self) -> Dict[str,
       "extra_5": py[9],
     }
 
+  async def iswap_rotation_drive_request_predefined_y_positions(self) -> Dict[str, float]:
+    """Read iSWAP rotation-drive Y predefined-position table in mm.
+
+    Wraps `_iswap_rotation_drive_request_predefined_y_positions`, converting
+    each value via `iswap_y_drive_increment_to_mm`.
+
+    Raises:
+      RuntimeError: if the iSWAP module is not installed.
+    """
+    table = await self._iswap_rotation_drive_request_predefined_y_positions()
+    return {k: STARBackend.iswap_y_drive_increment_to_mm(v) for k, v in table.items()}
+
   async def iswap_rotation_drive_move_z(
     self,
     z: float,
@@ -10160,7 +10172,7 @@ async def iswap_rotation_drive_move_z(
       zw=f"{int(current_protection_limiter)}",
     )
 
-  async def iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str, int]:
+  async def _iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str, int]:
     """Read the iSWAP rotation-drive Z-axis predefined-position table from EEPROM.
 
     Sends R0 RA ra=pz. Firmware returns 10 signed-integer slots; all 10 are
@@ -10199,6 +10211,18 @@ async def iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str,
       "extra_8": pz[9],
     }
 
+  async def iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str, float]:
+    """Read iSWAP rotation-drive Z predefined-position table in mm.
+
+    Wraps `_iswap_rotation_drive_request_predefined_z_positions`, converting
+    each value via `iswap_z_drive_increment_to_mm`.
+
+    Raises:
+      RuntimeError: if the iSWAP module is not installed.
+    """
+    table = await self._iswap_rotation_drive_request_predefined_z_positions()
+    return {k: STARBackend.iswap_z_drive_increment_to_mm(v) for k, v in table.items()}
+
   async def iswap_rotation_drive_request_predefined_positions(self) -> Dict[str, int]:
     """Read the iSWAP rotation drive (W) predefined-position table from EEPROM.
 

From f9a322cef78d2e3e512ea6d46f5fc6790986a8ca Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 18:18:26 +0100
Subject: [PATCH 18/21] make everything that references rotation drive return
 rotation drive data

---
 .../backends/hamilton/STAR_backend.py         | 33 +++++++++++--------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index 99700a6eee0..c211fb2d17e 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -9891,9 +9891,9 @@ async def iswap_rotation_drive_request_y(self) -> float:
     iswap_y_pos = resp["ry"][1]  # 0 = FW counter, 1 = HW counter
     return round(STARBackend.iswap_y_drive_increment_to_mm(iswap_y_pos), 1)
 
-  # Vertical drop from the iSWAP rotation drive plane to the gripper finger
-  # plane. R0 RZ is calibrated to the finger plane; the rotation drive sits
-  # 13 mm above it.
+  # Vertical offset between the rotation drive's bottom (its lowest physical
+  # point) and the gripper finger plane. R0 RZ is calibrated to the finger
+  # plane; the rotation drive's bottom sits 13 mm above it.
   iswap_rotation_drive_z_offset_above_finger_mm = 13.0
 
   # Z increment ranges below are in finger-plane coords (the R0 ZA reference).
@@ -9905,9 +9905,10 @@ async def iswap_rotation_drive_request_y(self) -> float:
   iswap_rotation_drive_z_acceleration_increment_range = (5, 999)
 
   async def iswap_rotation_drive_request_z(self) -> float:
-    """Request iSWAP rotation drive Z position (deck coordinates), in mm.
+    """Request iSWAP rotation-drive-bottom Z (deck coordinates), in mm.
 
-    Adds the 13 mm structural offset to the gripper finger plane (C0 QG).
+    Returns the Z of the rotation drive's lowest physical point, which sits
+    13 mm above the gripper finger plane that C0 QG reports.
     """
     if not self.extended_conf.left_x_drive.iswap_installed:
       raise RuntimeError("iSWAP is not installed")
@@ -10102,14 +10103,14 @@ async def iswap_rotation_drive_move_z(
     acceleration: float = 643.66,
     current_protection_limiter: int = 6,
   ):
-    """Move the iSWAP rotation drive to an absolute Z position (deck coordinates).
+    """Move the iSWAP rotation-drive bottom to an absolute Z (deck coordinates).
 
-    `z` is the rotation-drive plane Z, matching what
-    `iswap_rotation_drive_request_z` returns. The 13 mm offset to the gripper
-    finger plane (where R0 ZA is calibrated) is applied internally.
+    `z` is the rotation-drive bottom Z (lowest physical point of the drive),
+    matching what `iswap_rotation_drive_request_z` returns. The 13 mm offset
+    to the finger plane (R0 ZA reference) is applied internally.
 
     Args:
-      z: Target rotation-drive Z coordinate in mm.
+      z: Target rotation-drive-bottom Z coordinate in mm.
       speed: Max velocity in mm/sec. Default 118.0 (firmware default).
       acceleration: Acceleration in mm/sec^2. Default 643.66
         (firmware default 60 in 1000 incr/sec^2 units).
@@ -10214,14 +10215,20 @@ async def _iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str
   async def iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str, float]:
     """Read iSWAP rotation-drive Z predefined-position table in mm.
 
-    Wraps `_iswap_rotation_drive_request_predefined_z_positions`, converting
-    each value via `iswap_z_drive_increment_to_mm`.
+    Returns rotation-drive-bottom Z (matching `iswap_rotation_drive_request_z`
+    and `iswap_rotation_drive_move_z`). Wraps the increment private method,
+    converts via `iswap_z_drive_increment_to_mm`, then adds
+    `iswap_rotation_drive_z_offset_above_finger_mm` so EEPROM finger-plane
+    increments map to deck-coordinate mm at the rotation drive's bottom.
 
     Raises:
       RuntimeError: if the iSWAP module is not installed.
     """
     table = await self._iswap_rotation_drive_request_predefined_z_positions()
-    return {k: STARBackend.iswap_z_drive_increment_to_mm(v) for k, v in table.items()}
+    offset = STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
+    return {
+      k: STARBackend.iswap_z_drive_increment_to_mm(v) + offset for k, v in table.items()
+    }
 
   async def iswap_rotation_drive_request_predefined_positions(self) -> Dict[str, int]:
     """Read the iSWAP rotation drive (W) predefined-position table from EEPROM.

From dbfcb0b2de6473abc6f6fb43adaad4926c259958 Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 18:28:38 +0100
Subject: [PATCH 19/21] `make format`

---
 .../liquid_handling/backends/hamilton/STAR_backend.py       | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index c211fb2d17e..4e4ac9529bd 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -10182,7 +10182,7 @@ async def _iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str
 
     Keys (motor increments; see `iswap_z_drive_mm_per_increment`):
       "home"     pz[0]  - home position
-      "parking"  pz[1]  - parking pose (top of travel)
+      "parking"  pz[1]  - parking pose
       "extra_1"  pz[2]  - extra slot, address via R0 ZP zp2
       "extra_2"  pz[3]  - extra slot, address via R0 ZP zp3
       "extra_3"  pz[4]  - extra slot, address via R0 ZP zp4
@@ -10226,9 +10226,7 @@ async def iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str,
     """
     table = await self._iswap_rotation_drive_request_predefined_z_positions()
     offset = STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
-    return {
-      k: STARBackend.iswap_z_drive_increment_to_mm(v) + offset for k, v in table.items()
-    }
+    return {k: STARBackend.iswap_z_drive_increment_to_mm(v) + offset for k, v in table.items()}
 
   async def iswap_rotation_drive_request_predefined_positions(self) -> Dict[str, int]:
     """Read the iSWAP rotation drive (W) predefined-position table from EEPROM.

From c8566d51085d74bdb44644ca3beb8fd99b10b011 Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 18:34:46 +0100
Subject: [PATCH 20/21] simplify: compress increment and mm returns into one
 method

---
 .../backends/hamilton/STAR_backend.py         | 88 +++++++------------
 1 file changed, 34 insertions(+), 54 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index 4e4ac9529bd..a8cc016e4a8 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -10045,14 +10045,14 @@ async def iswap_rotation_drive_move_y(
       yw=f"{int(current_protection_limiter)}",
     )
 
-  async def _iswap_rotation_drive_request_predefined_y_positions(self) -> Dict[str, int]:
-    """Read the iSWAP rotation-drive Y-axis predefined-position table from EEPROM.
+  async def iswap_rotation_drive_request_predefined_y_positions(self) -> Dict[str, float]:
+    """Read iSWAP rotation-drive Y predefined-position table from EEPROM, in mm.
 
     Sends R0 RA ra=py. Firmware returns 10 signed-integer slots; all 10 are
     positions (no length slot, unlike pw/pt). Slots beyond the documented
     semantic roles are extra slots addressable via R0 YP yp5..yp9.
 
-    Keys (motor increments; see `iswap_y_drive_mm_per_increment`):
+    Keys (mm):
       "home"         py[0]  - home position
       "lower_limit"  py[1]  - lower travel limit
       "upper_limit"  py[2]  - upper travel limit
@@ -10071,31 +10071,20 @@ async def _iswap_rotation_drive_request_predefined_y_positions(self) -> Dict[str
       raise RuntimeError("iSWAP is not installed")
     resp = await self.send_command(module="R0", command="RA", ra="py", fmt="py##### (n)")
     py = cast(List[int], resp["py"])
+    to_mm = STARBackend.iswap_y_drive_increment_to_mm
     return {
-      "home": py[0],
-      "lower_limit": py[1],
-      "upper_limit": py[2],
-      "parking": py[3],
-      "pre_parking": py[4],
-      "extra_1": py[5],
-      "extra_2": py[6],
-      "extra_3": py[7],
-      "extra_4": py[8],
-      "extra_5": py[9],
+      "home": to_mm(py[0]),
+      "lower_limit": to_mm(py[1]),
+      "upper_limit": to_mm(py[2]),
+      "parking": to_mm(py[3]),
+      "pre_parking": to_mm(py[4]),
+      "extra_1": to_mm(py[5]),
+      "extra_2": to_mm(py[6]),
+      "extra_3": to_mm(py[7]),
+      "extra_4": to_mm(py[8]),
+      "extra_5": to_mm(py[9]),
     }
 
-  async def iswap_rotation_drive_request_predefined_y_positions(self) -> Dict[str, float]:
-    """Read iSWAP rotation-drive Y predefined-position table in mm.
-
-    Wraps `_iswap_rotation_drive_request_predefined_y_positions`, converting
-    each value via `iswap_y_drive_increment_to_mm`.
-
-    Raises:
-      RuntimeError: if the iSWAP module is not installed.
-    """
-    table = await self._iswap_rotation_drive_request_predefined_y_positions()
-    return {k: STARBackend.iswap_y_drive_increment_to_mm(v) for k, v in table.items()}
-
   async def iswap_rotation_drive_move_z(
     self,
     z: float,
@@ -10173,14 +10162,19 @@ async def iswap_rotation_drive_move_z(
       zw=f"{int(current_protection_limiter)}",
     )
 
-  async def _iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str, int]:
-    """Read the iSWAP rotation-drive Z-axis predefined-position table from EEPROM.
+  async def iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str, float]:
+    """Read iSWAP rotation-drive Z predefined-position table from EEPROM, in mm.
 
     Sends R0 RA ra=pz. Firmware returns 10 signed-integer slots; all 10 are
     positions (no length slot, unlike pw/pt). Slots beyond home/parking are
     extra slots addressable via R0 ZP zp2..zp9.
 
-    Keys (motor increments; see `iswap_z_drive_mm_per_increment`):
+    Returns rotation-drive-bottom Z (matching `iswap_rotation_drive_request_z`
+    and `iswap_rotation_drive_move_z`): each EEPROM finger-plane increment is
+    converted via `iswap_z_drive_increment_to_mm` then offset by
+    `iswap_rotation_drive_z_offset_above_finger_mm`.
+
+    Keys (mm):
       "home"     pz[0]  - home position
       "parking"  pz[1]  - parking pose
       "extra_1"  pz[2]  - extra slot, address via R0 ZP zp2
@@ -10199,35 +10193,21 @@ async def _iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str
       raise RuntimeError("iSWAP is not installed")
     resp = await self.send_command(module="R0", command="RA", ra="pz", fmt="pz##### (n)")
     pz = cast(List[int], resp["pz"])
+    offset = STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
+    to_mm = STARBackend.iswap_z_drive_increment_to_mm
     return {
-      "home": pz[0],
-      "parking": pz[1],
-      "extra_1": pz[2],
-      "extra_2": pz[3],
-      "extra_3": pz[4],
-      "extra_4": pz[5],
-      "extra_5": pz[6],
-      "extra_6": pz[7],
-      "extra_7": pz[8],
-      "extra_8": pz[9],
+      "home": to_mm(pz[0]) + offset,
+      "parking": to_mm(pz[1]) + offset,
+      "extra_1": to_mm(pz[2]) + offset,
+      "extra_2": to_mm(pz[3]) + offset,
+      "extra_3": to_mm(pz[4]) + offset,
+      "extra_4": to_mm(pz[5]) + offset,
+      "extra_5": to_mm(pz[6]) + offset,
+      "extra_6": to_mm(pz[7]) + offset,
+      "extra_7": to_mm(pz[8]) + offset,
+      "extra_8": to_mm(pz[9]) + offset,
     }
 
-  async def iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str, float]:
-    """Read iSWAP rotation-drive Z predefined-position table in mm.
-
-    Returns rotation-drive-bottom Z (matching `iswap_rotation_drive_request_z`
-    and `iswap_rotation_drive_move_z`). Wraps the increment private method,
-    converts via `iswap_z_drive_increment_to_mm`, then adds
-    `iswap_rotation_drive_z_offset_above_finger_mm` so EEPROM finger-plane
-    increments map to deck-coordinate mm at the rotation drive's bottom.
-
-    Raises:
-      RuntimeError: if the iSWAP module is not installed.
-    """
-    table = await self._iswap_rotation_drive_request_predefined_z_positions()
-    offset = STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
-    return {k: STARBackend.iswap_z_drive_increment_to_mm(v) + offset for k, v in table.items()}
-
   async def iswap_rotation_drive_request_predefined_positions(self) -> Dict[str, int]:
     """Read the iSWAP rotation drive (W) predefined-position table from EEPROM.
 

From f747bf5956a10c175e93996a5d90ed51e942451e Mon Sep 17 00:00:00 2001
From: Camillo Moschner <camillo.moschner@biocam.guide>
Date: Fri, 1 May 2026 21:24:44 +0100
Subject: [PATCH 21/21] simplify z conversions

---
 .../backends/hamilton/STAR_backend.py         | 50 ++++++++++---------
 1 file changed, 26 insertions(+), 24 deletions(-)

diff --git a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
index a8cc016e4a8..10cfc65de36 100644
--- a/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
+++ b/pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py
@@ -10071,19 +10071,19 @@ async def iswap_rotation_drive_request_predefined_y_positions(self) -> Dict[str,
       raise RuntimeError("iSWAP is not installed")
     resp = await self.send_command(module="R0", command="RA", ra="py", fmt="py##### (n)")
     py = cast(List[int], resp["py"])
-    to_mm = STARBackend.iswap_y_drive_increment_to_mm
-    return {
-      "home": to_mm(py[0]),
-      "lower_limit": to_mm(py[1]),
-      "upper_limit": to_mm(py[2]),
-      "parking": to_mm(py[3]),
-      "pre_parking": to_mm(py[4]),
-      "extra_1": to_mm(py[5]),
-      "extra_2": to_mm(py[6]),
-      "extra_3": to_mm(py[7]),
-      "extra_4": to_mm(py[8]),
-      "extra_5": to_mm(py[9]),
-    }
+    keys = (
+      "home",
+      "lower_limit",
+      "upper_limit",
+      "parking",
+      "pre_parking",
+      "extra_1",
+      "extra_2",
+      "extra_3",
+      "extra_4",
+      "extra_5",
+    )
+    return {k: STARBackend.iswap_y_drive_increment_to_mm(py[i]) for i, k in enumerate(keys)}
 
   async def iswap_rotation_drive_move_z(
     self,
@@ -10194,18 +10194,20 @@ async def iswap_rotation_drive_request_predefined_z_positions(self) -> Dict[str,
     resp = await self.send_command(module="R0", command="RA", ra="pz", fmt="pz##### (n)")
     pz = cast(List[int], resp["pz"])
     offset = STARBackend.iswap_rotation_drive_z_offset_above_finger_mm
-    to_mm = STARBackend.iswap_z_drive_increment_to_mm
+    keys = (
+      "home",
+      "parking",
+      "extra_1",
+      "extra_2",
+      "extra_3",
+      "extra_4",
+      "extra_5",
+      "extra_6",
+      "extra_7",
+      "extra_8",
+    )
     return {
-      "home": to_mm(pz[0]) + offset,
-      "parking": to_mm(pz[1]) + offset,
-      "extra_1": to_mm(pz[2]) + offset,
-      "extra_2": to_mm(pz[3]) + offset,
-      "extra_3": to_mm(pz[4]) + offset,
-      "extra_4": to_mm(pz[5]) + offset,
-      "extra_5": to_mm(pz[6]) + offset,
-      "extra_6": to_mm(pz[7]) + offset,
-      "extra_7": to_mm(pz[8]) + offset,
-      "extra_8": to_mm(pz[9]) + offset,
+      k: STARBackend.iswap_z_drive_increment_to_mm(pz[i]) + offset for i, k in enumerate(keys)
     }
 
   async def iswap_rotation_drive_request_predefined_positions(self) -> Dict[str, int]: