pcdsdevices.signal.MultiDerivedSignal

Signal derived from multiple signals in the device hierarchy.

Requires a calculation function to be passed in. Support writing to multiple signals if an additional calculate_on_put function is supplied.

Functions may also be defined in a subclass for advanced or repeated usage.

Functions may or may be methods. If self is noted as the first argument of your function, it will be assumed to be a method. self will then refer to the MultiDerivedSignal instance.

Parameters:

attrs (list of str) – Attribute names of signals that are used to generate a value for this signal.
calculate_on_get (MdsCalculationFunction) – A calculation function that takes in a dictionary of signals to values. It should be made to return a value of a compatible ophyd data type, such as an integer, float, or an array.
calculate_on_put (MdsOnPutFunction) – A calculation function that allows this MultiDerivedSignal to be read-write instead of just read-only. It should take in a single value and return a dictionary of signal-to-value to write, each with a compatible ophyd data type, such as an integer, float, or an array. Values will be written to simultaneously and result in a single Status object.

Methods

add_signal_by_attr_name(name: str) → Signal

Add a signal from which to aggregate information.

This must be called before any subscriptions are made to the signal. Duplicate signals will not be re-added.

Parameters:: name (str) – The attribute name of the signal, relative to the parent device.
Returns:: sig (ophyd.Signal) – The signal referenced by the attribute name.
Raises:: RuntimError – If called after .subscribe() or used without a parent Device.

describe()

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)

Update all values and recalculate.

Parameters:: **kwargs – Keyword arguments are passed to each signal.get(**kwargs).

read()

Put the status of the signal into a simple dictionary format for data acquisition

Returns:: dict

read_configuration(): Dictionary mapping names to value dicts with keys: value, timestamp

Set the value of the Signal and return a Status object.

Returns:: st (Status) – This status object will be finished upon return in the case of basic soft Signals

trigger(): Call that is used by bluesky prior to read()

Attributes

SUB_META = 'meta'

connected: Are all relevant signals connected?

high_limit: The high, inclusive control limit for the Signal

hints: Field hints for plotting

kind

limits: The control limits (low, high), such that low <= value <= high

low_limit: The low, inclusive control limit for the Signal

metadata: A copy of the metadata dictionary associated with the signal

metadata_keys: Metadata keys that will be passed along on value subscriptions

read_access: Can the signal be read?

signals: The signals used to calculate_on_get this MultiDerivedSignal.

subscriptions: ClassVar[FrozenSet[str]] = frozenset({'meta', 'value'})

timestamp: Timestamp of the readback value

tolerance: The absolute tolerance associated with the value.

value: The signal’s value

write_access: Can the signal be written to?

calculate_on_get: MdsOnGetFunction

calculate_on_put: MdsOnPutFunction | None