pcdsdevices.signal.SignalEditMD

class pcdsdevices.signal.SignalEditMD(*, name, value=0.0, timestamp=None, parent=None, labels=None, kind=<Kind.hinted: 5>, tolerance=None, rtolerance=None, metadata=None, cl=None, attr_name='')

Subclass for allowing an external override of signal metadata.

This can be useful in cases where the signal metadata is wrong, not included properly in the signal, or where you’d like different metadata-dependent behavior than what is discovered via the cl.

Does some minimal checking against the signal’s metadata keys and ensures the override values always take priority over the normally found values.

Methods

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): The readback value

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(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

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

Attributes

SUB_META = 'meta'

connected: Is the signal connected to its associated hardware, and ready to use?

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

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

read_access: Can the signal be read?

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?