pcdsdevices.gon.Kappa

class pcdsdevices.gon.Kappa(*, name, prefix_x, prefix_y, prefix_z, prefix_eta, prefix_kappa, prefix_phi, eta_max_step=2, kappa_max_step=2, phi_max_step=2, kappa_ang=50, **kwargs)

Kappa stage, control the Kappa diffractometer in spherical coordinates.

The kappa’s native coordinates (eta, kappa, phi) are mechanically convenient, but geometrically awkward to think about. This module replaces the coordinates with (e_eta, e_chi, e_phi) like so:

The radial component is generally fixed such that the sample is at the center of rotation, but you may think of z as the radial component (inverted because the sample is pushed into the center of the coordinate system, rather than out from the center.)

Parameters:

• name (str) – A name to refer to the Kappa stage device.

• prefix_x (str) – The EPICS base PV of the Kappa stage’s x motor.

• prefix_y (str) – The EPICS base PV of the Kappa stage’s y motor.

• prefix_z (str) – The EPICS base PV of the Kappa stage’s z motor.

• prefix_eta (str) – The EPICS base PV of the Kappa stage’s eta motor.

• prefix_kappa (str) – The EPICS base PV of the Kappa stage’s kappa motor.

• prefix_phi (str) – The EPICS base PV of the Kappa stage’s phi motor.

• eta_max_step (int, optional) – Maximum eta motor step, the largest move eta motor can make without user’s confirmation. Defaults to 2.

• kappa_max_step (int, optional) – Maximum kappa motor step, the largest move kappa motor can make without user’s confirmation. Defaults to 2.

• phi_max_step (int, optional) – Maximum phi motor step, the largest move phi motor can make without user’s confirmation. Defaults to 2.

• kappa_ang (number, optional) – The angle of the kappa motor relative to the eta motor, in degrees. Defaults to 50.

Notes

When using the Kappa, it is most convenient to work through the pseudo motors:

kappa.e_eta kappa.e_chi kappa.e_phi

Which have the normal motor functionalities (mv, mvr, wm).

It may be helpful to scan these pseudo motors to find the optimal position, but make sure the step size is small enough so that you don’t have to confirm motion on every step.

Move commands will block the main thread, and pressing ctrl+c will cancel motion.

The x, y, and z are the sample adjustment motors used to attain center of rotation

Ophyd Device Components

Attribute	Class	Suffix	Docs	Kind	Notes
sample_stage	KappaXYZStage			normal
eta (FCpt)	IMS	{self._prefix_eta}		normal
kappa (FCpt)	IMS	{self._prefix_kappa}		normal
phi (FCpt)	IMS	{self._prefix_phi}		normal
e_eta (FCpt)	PseudoSingleInterface			normal
e_chi (FCpt)	PseudoSingleInterface			normal
e_phi (FCpt)	PseudoSingleInterface			normal

Methods

check_motor_step(eta, kappa, phi)

Check for the motor steps.

Compare desired movement destinations with current positions. If any of the deltas are greater than their respective max step, ask the user for confirmation.

Parameters:

• eta (number) – Desired eta destination position.

• kappa (number) – Desired kappa destination position.

• phi (number) – Desired phi destination position.

Returns:

move_on (bool) – True if motor step is smaller than the respective max step and/or the user has confirmed yes.

check_single(pseudo_single, single_pos)

Check if a new position for a single pseudo positioner is valid

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.

e_to_k(e_eta=None, e_chi=None, e_phi=None)

Convert from spherical coordinates to the native kappa coordinates.

If a parameter is left as None, use the live value.

Parameters:

• e_eta (number) – e_eta pseudo motor’s spherical coordinate

• e_chi (number) – e_chi pseudo motor’s spherical coordinate

• e_phi (number) – e_phi pseudo motor’s spherical coordinate

Returns:

coordinates (tuple) – Native kappa coordinates.

forward(pseudo_pos)

Calculate a RealPosition from a given PseudoPosition.

Parameters:

pseudo_pos (PseudoPosition) – The pseudo position input.

Returns:

real_position (RealPosition) – The real position output.

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.

inverse(real_pos)

Calculate a PseudoPosition from a given RealPosition.

Parameters:

real_position (RealPosition) – The real position input.

Returns:

pseudo_pos (PseudoPosition) – The pseudo position output.

k_to_e(eta=None, kappa=None, phi=None)

Convert from native kappa coordinates to spherical coordinates.

If a parameter is left as None, use the live value.

Parameters:

• eta (number) – Eta motor position.

• kappa (number) – Kappa motor position.

• phi (number) – Phi motor position.

Returns:

coordinates (tuple) – Spherical coordinates.

move(position, wait=True, timeout=None, moved_cb=None)

Move to a specified position, optionally waiting for motion to complete.

Checks for the motor step, and ask the user for confirmation if movement step is greater than default one.

move_single(pseudo, position, **kwargs)

Move one PseudoSingle axis to a position

All other positioners will use their current setpoint/target value, if available. Failing that, their current readback value will be used (see PseudoSingle.sync and PseudoSingle.target).

Parameters:

• pseudo (PseudoSingle) – PseudoSingle positioner to move

• position (float) – Position only for the PseudoSingle

• kwargs (dict) – Passed onto move

post_elog_status()

Post device status to the primary elog, if possible.

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.

set(position, **kwargs)

Move to a new position asynchronously

Parameters:

position (PseudoPosition) – Position for the all of the pseudo axes

Returns:

status (MoveStatus)

set_current_position(position)

Adjust all offsets so that the pseudo position matches the input.

This will raise an AttributeError if any of the real motors is missing a set_current_position method.

Parameters:

position (PseudoPos) – The position

stage_group_instances() → Iterator[OphydObject]

Yields an iterator of subdevices that should be staged.

status() → str

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

stop(success=False)

Stop the Device and all (instantiated) subdevices

summary()

to_pseudo_tuple(*args, **kwargs)

Convert arguments to a PseudoPosition namedtuple and kwargs

to_real_tuple(*args, **kwargs)

Convert arguments to a RealPosition namedtuple and kwargs

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.

wait(timeout=None)

Block until the action completes.

Attributes

composite_egu

The composite engineering units (EGU) from all PseudoSingles

concurrent

If concurrent is set, motors will move concurrently (in parallel)

configuration_attrs

connected

e_chi_coord

Get the elevation (polar) angle, a composition of eta and kappa.

e_eta_coord

Get the azimuthal angle, an offset from eta.

e_phi_coord

Get the sample rotation angle, an offset from phi to keep it.

egu

The engineering units (EGU) for positions

high_limit

All PseudoSingle high limits as a namedtuple

hints

kind

limits

All PseudoSingle limits as a namedtuple

low_limit

All PseudoSingle low limits as a namedtuple

moving

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'>]

position

Pseudo motor position namedtuple

pseudo_positioners

Pseudo positioners instances in a namedtuple

Returns:

positioner_instances (PseudoPosition)

real_position

Real motor position namedtuple

real_positioners

Real positioners instances in a namedtuple

Returns:

positioner_instances (RealPosition)

sequential

If sequential is set, motors will move in the sequence they were defined in (i.e., in series)

settle_time

Amount of time to wait after moves to report status completion

stage_group: list[Component] = [FormattedComponent(IMS, '{self._prefix_eta}', kind='normal'), FormattedComponent(IMS, '{self._prefix_kappa}', kind='normal'), FormattedComponent(IMS, '{self._prefix_phi}', kind='normal')]

subscriptions: ClassVar[FrozenSet[str]] = frozenset({'_req_done', 'acq_done', 'done_moving', 'readback', 'start_moving'})

target

Last commanded target positions

timeout

Amount of time to wait before to considering a motion as failed