pcdsdevices.ccm.CCMConstantsMixin

class pcdsdevices.ccm.CCMConstantsMixin(prefix: str, *args, **kwargs)

Mixin class that includes PVs that hold CCM constants.

This allows us to keep the CCM parameters synchronized between sessions and between different devices in the same session.

Contains user PVs for theta0, dspacing, gr, and gd. These are intended to be run from the user pv notepad IOCs and are available in the most recent tags.

Prefix can be any of the prefixes from any of the CCM motors.

Ophyd Device Components
Attribute	Class	Suffix	Docs	Kind
theta0_deg (FCpt)	`EpicsSignal`	`{_constants_prefix}:THETA0`	Reference angle for the first crystal in deg.	config
dspacing (FCpt)	`EpicsSignal`	`{_constants_prefix}:DSPACING`	Crystal lattice spacing.	config
gr (FCpt)	`EpicsSignal`	`{_constants_prefix}:GR`	The radius of the sapphire ball connected to the Alio stage in mm.	config
gd (FCpt)	`EpicsSignal`	`{_constants_prefix}:GD`	Distance between the rotation axis and the center of the sapphire sphere located on the Alio stage in mm.	config

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.

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.

reset_calc_constant_defaults(confirm: bool = True) → None

Put the default values into the ccm constants.

This can be useful if values were reset due to autosave errors or if they’ve otherwise accidentally been set to crazy values.

This relies on the default values in ccm.py being set up reasonably: theta0_deg = 15.1027 dspacing = 3.1356011499587773 gr = 3.175 gd = 231.303

Parameters:: confirm (bool, optional) – If True, we’ll ask for confirmation from the user before doing the reset. This is because an accidental reset can cost some time as we scramble to figure out what the values should be restored to.

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.

warn_invalid_constants(only_new: bool = False) → None

Warn if we have invalid values for our calculation constants.

The motivation here is twofold: 1. It should be easy for the user to know what is wrong and

why. The calculations should not be opaque.

The user should still be able to do “something” if there is an issue here.

For values to be valid, the PVs need to be connected and all but theta0 must be nonzero. Theta0 should also not be zero, but it doesn’t break the math and someone could conceivably set it to zero during debug.

If this isn’t satisfied, we will show an appropriate warning message when this method is called. The intention is for this to pop up whenever we run the forward/inverse calculations.

For more detail, consider the following failure modes: 1. The constant PVs don’t connect and never connect

In this case, we must warn that the constants IOC is off

We should use the default values in calculations

The constant PVs connect, but their values are zero

In this case, we must warn that the constant values were lost

We should use the default values in calculations

The constant PVs connect, but disconnect later

In this case, we should warn that the IOC died

We should continue using the last known good values

Parameters:: only_new (bool, optional) – If False, the default, always show us the warnings. If True, do not show warnings if they have not changed.

Attributes

configuration_attrs

connected

dspacing_val

The dspacing value currently used in calculations.

This is the crystal lattice spacing.

This will be the value from the PV if things are working properly, otherwise it will fall back to the default value.

This is necessary because a value of 0 is nonphysical and in the case of a disconnected value the show must go on.

gd_val

The gd value currently used in calculations.

This is the distance between the rotation axis and the center of the sapphire sphere located on the Alio stage in mm.

This will be the value from the PV if things are working properly, otherwise it will fall back to the default value.

This is necessary because a value of 0 is nonphysical and in the case of a disconnected value the show must go on.

gr_val

The gr value currently used in calculations.

This is the radius of the sapphire ball connected to the Alio stage in mm.

This will be the value from the PV if things are working properly, otherwise it will fall back to the default value.

This is necessary because a value of 0 is nonphysical and in the case of a disconnected value the show must go on.

hints

kind

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

theta0_deg_val

The theta0 value currently used in calculations.

This is the reference angle for the first crystal in deg.

This will be the value from the PV if things are working properly, otherwise it will fall back to the default value.

theta0_rad_val

The theta0 value currently used in calculations.

This is the reference angle for the first crystal in rad.

This will be the value from the PV if things are working properly, otherwise it will fall back to the default value.