pylabrobot.liquid_handling.backends.hamilton.STAR_backend.STAR.request_presence_of_carriers_on_loading_tray

async STAR.request_presence_of_carriers_on_loading_tray() → list[int]

Moves autoload sled across loading tray and reads its front-facing proximity sensors to determine which tray positions contain carriers.

This sends the C0:CS command, which provides a hex-encoded presence bitmask for the loading tray. The bitmask is decoded into a list of track numbers (1-54) representing tray positions that currently contain a carrier.

Returns:

list[int] – Sorted list of loading-tray positions where carriers are present.

Raises:

ValueError – If the response is missing the expected ‘cd’ field.

Return type:

list[int]