pcdsdevices.device.GroupDevice

class pcdsdevices.device.GroupDevice(*args, **kwargs)

A device that is a group of components that will act independently.

This has the following implications: - Components will have no references to this parent device. If

accessed and used out of context, the components will be as if they were instantited completely separately.

  • The parent device will be stashed in the biological_parent attribute, in case it’s needed (by something other than the RE)

  • If a component is staged in a bluesky plan, it will not stage the GroupDevice, and therefore will not stage the entire device tree.

  • GroupDevice instances by default do nothing when staged. You can add specific subdevices to the stage list by setting the stage_group class attribute to a list of components.

  • Following from the previous point, note that GroupDevice instances cannot process top-level stage_sigs. If you need top-level stage_sigs, you should instead contain them in a subdevice that is not a GroupDevice.

  • GroupDevice instances that implement set are required to specify a stage_group to help remind you that these classes really do need to stage “something” before scanning. If your movable device really does not need this, you can set stage_group to an empty list.

  • When represented in typhos, we’ll see the GroupDevice screen instead of the default device screens. (Note: at time of writing, this hypothetical GroupDevice ui template does not yet exist).

  • Certain devices will completely break if we remove their subdevice references: for example, consider the PsuedoPositioner class. For classes like these, we’ll need to keep the parent references for the PseudoSingle instances. For the full list of classes that need to retain their parent attribute, see GroupDevice.needs_parent.

Methods

configure(d: Dict[str, Any]) → Tuple[Dict[str, Any], Dict[str, Any]]

Configure the device for something during a run

This default implementation allows the user to change any of the configuration_attrs. Subclasses might override this to perform additional input validation, cleanup, etc.

Parameters:

d (dict) – The configuration dictionary. To specify the order that the changes should be made, use an OrderedDict.

Returns:

  • (old, new) tuple of dictionaries

  • Where old and new are pre- and post-configure configuration states.

describe() → OrderedDictType[str, Dict[str, Any]]

Provide schema and meta-data for read().

This keys in the OrderedDict this method returns must match the keys in the OrderedDict return by read().

This provides schema related information, (ex shape, dtype), the source (ex PV name), and if available, units, limits, precision etc.

Returns:

data_keys (OrderedDict) – The keys must be strings and the values must be dict-like with the event_model.event_descriptor.data_key schema.

get(**kwargs)

Get the value of all components in the device

Keyword arguments are passed onto each signal.get(). Components beginning with an underscore will not be included.

read() → OrderedDictType[str, Dict[str, Any]]

Read data from the device.

This method is expected to be as instantaneous as possible, with any substantial acquisition time taken care of in trigger().

The OrderedDict returned by this method must have identical keys (in the same order) as the OrderedDict returned by describe().

By convention, the first key in the return is the ‘primary’ key and maybe used by heuristics in bluesky.

The values in the ordered dictionary must be dict (-likes) with the keys {'value', 'timestamp'}. The 'value' may have any type, the timestamp must be a float UNIX epoch timestamp in UTC.

Returns:

data (OrderedDict) – The keys must be strings and the values must be dict-like with the keys {'value', 'timestamp'}

read_configuration() → OrderedDictType[str, Dict[str, Any]]

Dictionary mapping names to value dicts with keys: value, timestamp

To control which fields are included, change the Component kinds on the device, or modify the configuration_attrs list.

classmethod set_defaults(*, connection_timeout=10.0)

Set class-wide defaults for device communications

This may be called only before any instances of Device are made.

This setting applies to the class it is called on and all its subclasses. For example,

>>> Device.set_defaults(...)

will apply to any Device subclass.

Parameters:

connection_timeout (float, optional) – Time (seconds) allocated for establishing a connection with the IOC.

Raises:

RuntimeError – If called after EpicsSignalBase has been instantiated for the first time.

stage_group_instances() → Iterator[OphydObject]

Yields an iterator of subdevices that should be staged.

stop(*, success=False)

Stop the Device and all (instantiated) subdevices

summary()
trigger() → StatusBase

Trigger the device and return status object.

This method is responsible for implementing ‘trigger’ or ‘acquire’ functionality of this device.

If there is an appreciable time between triggering the device and it being able to be read (via the read() method) then this method is also responsible for arranging that the StatusBase object returned by this method is notified when the device is ready to be read.

If there is no delay between triggering and being readable, then this method must return a StatusBase object which is already completed.

Returns:

status (StatusBase) – StatusBase object which will be marked as complete when the device is ready to be read.

Attributes

configuration_attrs
connected
connection_timeout
hints
kind
needs_parent: list[type[OphydObject]] = [<class 'ophyd.signal.AttributeSignal'>, <class 'ophyd.signal.DerivedSignal'>, <class 'ophyd.areadetector.plugins.PluginBase'>, <class 'ophyd.pseudopos.PseudoSingle'>, <class 'pcdsdevices.signal.PVStateSignal'>, <class 'pcdsdevices.signal.AggregateSignal'>]
stage_group: list[Component] = None
subscriptions: ClassVar[FrozenSet[str]] = frozenset({'acq_done'})