Write Devices for Blueapi#

Format#

See also

Dodal for many more examples

Devices are made using the dodal style available through factory functions like this:

from my_facility_devices import MyTypeOfDetector

def my_detector(name: str) -> MyTypeOfDetector:
    return MyTypeOfDetector(name, {"other_config": "foo"})

The return type annotation -> MyTypeOfDetector is required as blueapi uses it to determine that this function creates a device. Meaning you can have a Python file where only some functions create devices and they will be automatically picked up. Similarly, these functions can be organized per-preference into files.

The device is created via a function rather than a global to preserve side-effect-free imports. Each device must have its own factory function.

How to Configure Detectors to Write Files#

Note

This is an absolute requirement to write data onto the Diamond Filesystem. This decorator must be used every time a new data collection is intended to begin. For an example, see below.

Dodal defines a decorator, @attach_data_session_metadata_decorator(), for configuring ophyd-async detectors to write data to a common location.

   @attach_metadata
   def ophyd_async_snapshot(
       detectors: List[Readable],
       metadata: Optional[dict[str, Any]] = None,
       ) -> MsgGenerator:
       Configures a number of devices, which may be Ophyd-Async detectors and require
       knowledge of where to write their files, then takes a snapshot with them.
       Args:
           detectors (List[Readable]): Devices, maybe including Ophyd-Async detectors.
       Returns:
           MsgGenerator: Plan
       Yields:
               Iterator[MsgGenerator]: Bluesky messages
       yield from count(detectors, 1, metadata or {})

   def repeated_snapshot(
       detectors: List[Readable],
       metadata: Optional[dict[str, Any]] = None,
       ) -> MsgGenerator:
       Configures a number of devices, which may be Ophyd-Async detectors and require
       knowledge of where to write their files, then takes multiple snapshot with them.
       Args:
           detectors (List[Readable]): Devices, maybe including Ophyd-Async detectors.
       Returns:
           MsgGenerator: Plan
       Yields:
               Iterator[MsgGenerator]: Bluesky messages
       @attach_metadata
       def inner_function():
           yield from count(detectors, 1, metadata or {})


       for _ in range(5):
           yield from inner_function()