pcdsdevices.sequencer.EventSequence

class pcdsdevices.sequencer.EventSequence(*args, **kwargs)

Class for the event sequence of the event sequencer.

Ophyd Device Components

Attribute	Class	Suffix	Docs	Kind	Notes
ec_array	EpicsSignal	:SEQ.A		normal
bd_array	EpicsSignal	:SEQ.B		normal
fd_array	EpicsSignal	:SEQ.C		normal
bc_array	EpicsSignal	:SEQ.D		normal
seq_proc	EpicsSignal	:SEQ.PROC		normal

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.

get_seq(current_length=True)

Retrieve the current event sequence.

Returns a list of lists, with each sub-list containing a four item list describing a single line of the sequence. Returns the current sequence up to the current play length (the ‘{prefix}:LEN’ PV), unless the current_length option is set to False. If False, the whole sequence will be returned.

Parameters:

current_length (bool) – Option to retrieve the sequence up to the current length. Defaults to True.

Examples

>>> EventSequence.get_seq()

Get the whole sequence: >>> EventSequence.get_seq(current_length=False)

post_elog_status()

Post device status to the primary elog, if possible.

put_seq(sequence, update_length=True)

Write a sequence to the event sequencer.

Takes a list of lists, with each sub-list representing one line of the event sequence, e.g. [beam_code, delta_beam, delta_fiducial, burst_count]. The written sequence will overwrite the current sequence in order, up to the specified length. The play length of the sequencer will automatically be updated, unless the update_length flag is set to False.

Parameters:

• sequence (list) – List of lists describing the event sequence. The list takes the form [[beam_code, delta_beam, delta_fiducial, burst_count], ...].

• update_length (bool) – Option to automatically update the play length (the ‘{prefix}:LEN’ PV) to the length of the written sequence. Defaults to True.

Examples

>>> seq = [[182,  12,   0,   0], # Line 1
           [170,   2,   0,   0], # Line 2
           [169,   1,   0,   0], # Line 3
           [169,   1,   0,   0]] # Line 4

>>> EventSequence.put_seq(seq)

Don’t update length: >>> EventSequence.put_seq(seq, update_length=False)

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.

screen()

Open a screen for controlling the device.

Default behavior is the typhos screen, but this method can be overridden for more specialized screens.

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.

show(num_lines=None)

Print a human readable copy of the current event sequence.

Shows the current sequence up to the length of the sequencer play length, unless otherwise specified by the num_lines parameter.

Parameters:

num_lines (int) – Number of event sequence lines to print. Defaults to current sequence length.

Examples

Print current sequence (default): >>> seq.show()

Print the first 10 lines: >>> seq.show(10)

status() → str

Returns a str with the current pv values for the device.

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

subscriptions: ClassVar[FrozenSet[str]] = frozenset({'acq_done'})