Devices

A device is a persistent process that exposes methods to tasks. It can control physical equipment or hold virtual state across protocol runs. EOS creates device processes when loading a lab. For objects that only need exclusive allocation, use Resources.

The GC Sampling task uses a gas chromatograph and a robot for sample injection.

Device Implementation

• Devices are implemented in the devices subdirectory inside an EOS package

• Each device has its own subfolder (e.g., devices/magnetic_mixer)

• There are two key files per device: device.yml and device.py

YAML File (device.yml)

• Specifies the device type, desc, and initialization parameters

• The same implementation can be used for multiple devices of the same type

• Initialization parameters can be overridden in laboratory definition

Example device YAML for a magnetic mixer:

device.yml

type: magnetic_mixer
desc: Magnetic mixer for mixing the contents of a container

init_parameters:
  port: 5004

Python File (device.py)

• Implements device functionality

• All devices implementations must inherit from BaseDevice

Example magnetic mixer implementation:

device.py

from typing import Any

from eos.resources.entities.resource import Resource
from eos.devices.base_device import BaseDevice
from user.eos_examples.color_lab.common.device_client import DeviceClient


class MagneticMixer(BaseDevice):
    async def _initialize(self, init_parameters: dict[str, Any]) -> None:
        port = int(init_parameters["port"])
        self.client = DeviceClient(port)
        self.client.open_connection()

    async def _cleanup(self) -> None:
        self.client.close_connection()

    async def _report(self) -> dict[str, Any]:
        return {}

    def mix(self, container: Resource, mixing_time: int, mixing_speed: int) -> Resource:
        result = self.client.send_command("mix", {"mixing_time": mixing_time, "mixing_speed": mixing_speed})
        if result:
            container.meta["mixing_time"] = mixing_time
            container.meta["mixing_speed"] = mixing_speed

        return container

Required lifecycle methods are _initialize to open connections, _cleanup to release them, and _report to return current state. Task-facing methods such as mix perform device actions and may update resource metadata.