pcdsdevices.signal.AggregateSignal

class pcdsdevices.signal.AggregateSignal(*, name, value=None, **kwargs)

Signal that is composed of a number of other signals.

This class exists to handle the group subscriptions without repeatedly getting the values of all the subsignals at all times.

This signal type is intended to be used programmatically with a subclass. For simple per-device usage, see MultiDerivedSignal.

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

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

set(value, *, timeout=None, settle_time=None, **kwargs)

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

Attributes

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