pcdsdevices.pseudopos.SyncAxis

class pcdsdevices.pseudopos.SyncAxis(*args, **kwargs)

Pseudomotor class for moving motors with linear relationships.

This will move all axes in a configurable coordinated way. It handles all cases where the motor coordination can be described by a simple scale and offset (multiply by a number, then add a number).

The calculation for moves is simply: pos = sync * scale + offset

Where sync is the pseudomotor’s position and every real motor can have a unique scale and offset.

The default settings will simply move all included real motors to the same value when the sync motor is moved. That is to say, a scale of 1 and an offset of 0.

You should subclass this by adding real motors as components. The class will pick them up and include them correctly into the coordinated move.

An example:

class Parallel(SyncAxis):
    left = Cpt(EpicsMotor, ':01')
    right = Cpt(EpicsMotor, ':02')

Like all ~ophyd.pseudopos.PseudoPositioner classes, any subclass of ~ophyd.positioner.PositionerBase will be included in the synchronized move.

See the following attributes for a dive into the settings and internals:

offset_mode

Selection of how and when offsets are interpreted. The default is STATIC_FIXED, which means “define static offsets at class creation and never change them.” Also available is AUTO_FIXED, which means “define offsets based on the current motor positions at the first move and do not change them during this session.”

Type:

SyncAxisOffsetMode (enum)

offsets

Specification of which offset to use for each motor. The mapping should be from attribute name to offset value. Any omitted motor will have an offset of default_offset.

Type:

dict {str: float} or None

default_offset

Any motor omitted from offsets will have this number assigned to them and its offset. The default value is 0.

Type:

float

scales

Specification of which scale to use for each motor. The mapping should be from attribute name to scale value. Any omitted motor will have a scale of default_scale.

Type:

dict {str: float} or None

default_scale

Any motor omitted from scales will have this number assigned to them and its scale. The default value is 1.

Type:

float

warn_inconsistent

If True (the default), warn the user if the real motors are not in a consistent position. An inconsistent position, or desync, can occur if a motor in the SyncAxis group has been moved manually.

Type:

bool

warn_deadband

How far out of sync our motors can be before we consider ourselves to be in an inconsistent, or desync state. Defaults to 0.001.

Type:

float

fix_sync_keep_still

Which motor to keep still when we recover the position using the fix_sync method. We will assume one motor (this motor) is in the correct position and move all the other motors to their correct positions. If omitted, the first motor will be considered the guiding motor that we do not move.

Type:

str or None

sync_limits

Limits to apply to the sync axis. Set these if you don’t think your real motor limits are sufficient to protect your application. e.g. sync_limits = (-100, 100) will bind the SyncAxis to move between -100 and 100.

Type:

tuple or None

Ophyd Device Components

Attribute

Class

Suffix

Docs

Kind

Notes

sync

PseudoSingleInterface

omitted

Methods

camonitor()

Shows a live-updating motor position in the terminal.

This will be the value that is returned by the position attribute.

This method ends cleanly at a ctrl+c or after a call to end_monitor_thread(), which may be useful when this is called in a background thread.

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.

consistency_warning()

Return the consistency warning text

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.

end_monitor_thread()

Stop a camonitor() or wm_update() that is running in another thread.

fix_sync(confirm=True, wait=True, timeout=10)

Method to re-synchronize the axes via motion.

This will move every motor except the one defined by the fix_sync_keep_still attribute, which will be used to define the correct position.

forward(pseudo_pos)

Calculate where to move each real motor when the sync moves.

The calculation is: 1. Multiply by scale 2. Add the offset

Offsets are defined in the class definition.

forward_single(attr, pos)

Run the forward calculation for a single real motor from the sync pos.

This gives us the real motor setpoint value for one axis.

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 where the sync motor is based on the first real motor.

The calculation is: 1. Subtract the offset 2. Divide by the scale

inverse_single(attr, pos)

Run the inverse calculation on a single real motor value.

This gives us the sync readback position.

is_synced(real_pos=None)

Check all motor positions for consistency.

This gets called in status_info if warn_inconsistent is True. If the motors are desyncronized greater than the warn_deadband, this will return False. Otherwise it will return True.

move(*args, **kwargs)

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

Parameters:

  • position – Pseudo position to move to.

  • moved_cb (callable) – Call this callback when movement has finished. This callback must accept one keyword argument: ‘obj’ which will be set to this positioner instance.

  • timeout (float, optional) – Maximum time to wait for the motion. If None, the default timeout for this positioner is used.

Returns:

status (MoveStatus)

Raises:
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

mv(position, timeout=None, wait=False, log=True)

Absolute move to a position.

Parameters:

  • position – Desired end position.

  • timeout (float, optional) – If provided, the mover will throw an error if motion takes longer than timeout to complete. If omitted, the mover’s default timeout will be use.

  • wait (bool, optional) – If True, wait for motion completion before returning. Defaults to False.

  • log (bool, optional) – If True, logs the move at INFO level.

mv_ginput(timeout=None)

Moves to a location the user clicks on.

If there are existing plots, this will be the position on the most recently active plot. If there are no existing plots, an empty plot will be created with the motor’s limits as the range.

mvr(delta, timeout=None, wait=False, log=True)

Relative move from this position.

Parameters:

  • delta (float) – Desired change in position.

  • timeout (float, optional) – If provided, the mover will throw an error if motion takes longer than timeout to complete. If omitted, the mover’s default timeout will be use.

  • wait (bool, optional) – If True, wait for motion completion before returning. Defaults to False.

  • log (bool, optional) – If True, logs the move at INFO level.

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

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.

set_position(position)

Alias for set_current_position.

Will fail if the motor does not have set_current_position.

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.

tweak(scale=0.1)

Control this motor using the arrow keys.

Use left arrow to step negative and right arrow to step positive. Use up arrow to increase step size and down arrow to decrease step size. Press q or ctrl+c to quit.

Parameters:

scale (float) – starting step size, default = 0.1

umv(position, timeout=None, log=True, newline=True)

Move to a position, wait, and update with a progress bar.

Parameters:

  • position (float) – Desired end position.

  • timeout (float, optional) – If provided, the mover will throw an error if motion takes longer than timeout to complete. If omitted, the mover’s default timeout will be use.

  • log (bool, optional) – If True, logs the move at INFO level.

  • newline (bool, optional) – If True, inserts a newline after the updates.

umvr(delta, timeout=None, log=True, newline=True)

Relative move from this position, wait, and update with a progress bar.

Parameters:

  • delta (float) – Desired change in position.

  • timeout (float, optional) – If provided, the mover will throw an error if motion takes longer than timeout to complete. If omitted, the mover’s default timeout will be use.

  • log (bool, optional) – If True, logs the move at INFO level.

  • newline (bool, optional) – If True, inserts a newline after the updates.

wait(timeout=None)
wm()

Get the mover’s current positon (where motor).

wm_update()

Shows a live-updating motor position in the terminal.

This will be the value that is returned by the position attribute.

This method ends cleanly at a ctrl+c or after a call to end_monitor_thread(), which may be useful when this is called in a background thread.

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
connection_timeout
default_offset = 0
default_scale = 1
egu

The engineering units (EGU) for positions

fix_sync_keep_still = None
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
offset_mode = 0
offsets = None
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)

scales = None
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

subscriptions: ClassVar[FrozenSet[str]] = frozenset({'_req_done', 'acq_done', 'done_moving', 'readback', 'start_moving'})
sync_limits = None
target

Last commanded target positions

timeout

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

warn_deadband = 0.001
warn_inconsistent = True