qcodes.instrument.delegate

class qcodes.instrument.delegate.delegate_instrument.DelegateInstrument(name: str, station: qcodes.station.Station, parameters: Optional[Union[Mapping[str, Sequence[str]], Mapping[str, str]]] = None, channels: Optional[Union[Mapping[str, Mapping[str, Any]], Mapping[str, str]]] = None, initial_values: Optional[Mapping[str, Any]] = None, set_initial_values_on_load: bool = False, setters: Optional[Mapping[str, MutableMapping[str, Any]]] = None, units: Optional[Mapping[str, str]] = None, metadata: Optional[Mapping[Any, Any]] = None)[source]

Bases: qcodes.instrument.base.InstrumentBase

DelegateInstrument is an instrument driver with one or more parameters that connect to instrument parameters.

Example usage in instrument YAML:

field:
    type: qcodes.instrument.delegate.DelegateInstrument
    init:
    parameters:
        X:
            - field_X.field
        ramp_rate:
            - field_X.ramp_rate
    channels:
        gate_1: dac.ch01
    set_initial_values_on_load: true
    initial_values:
        ramp_rate: 0.02
    setters:
        X:
            method: field_X.set_field
            block: false
    units:
        X: T
        ramp_rate: T/min

this will generate an instrument named “field” with methods:

field.X()
field.ramp_rate()

that are delegate parameters for:

field_X.field()
field_X.ramp_rate()

Additionally, this will set field_X.ramp_rate(0.02)` on load and override the field.X.set() method with

field_X.set_field(value, block=False),

as opposed to field.X.field.set() which ramps with block=True.

Parameters
  • name – Instrument name

  • station – Station containing the real instrument that is used to get the endpoint parameters.

  • parameters – A mapping from the name of a parameter to the sequence of source parameters that it points to.

  • channels – A mapping from the name of an instrument channel to either the channel it emulates or a mapping of keyworded input parameters of a custom channel wrapper class. This custom channel wrapper class needs to be specified under the type keyword. Each channel can have its own type if required. A single type for all channels can also be specified.

  • initial_values – Default values to set on the delegate instrument’s parameters. Defaults to None (no initial values are specified or set).

  • set_initial_values_on_load – Flag to set initial values when the instrument is loaded. Defaults to False.

  • setters – Optional setter methods to use instead of calling the .set() method on the endpoint parameters. Defaults to None.

  • units – Optional units to set for parameters.

  • metadata – Optional metadata to pass to instrument. Defaults to None.

param_cls

alias of qcodes.instrument.delegate.grouped_parameter.DelegateGroupParameter

static parse_instrument_path(parent: Union[qcodes.station.Station, qcodes.instrument.base.InstrumentBase], path: str) Any[source]

Parse a string path and return the object relative to a station or instrument, e.g. “my_instrument.my_param” returns station.my_instrument.my_param

Parameters
  • parent – Measurement station

  • path – Relative path to parse

set_initial_values(dry_run: bool = False) None[source]

Set parameter initial values on delegate instrument

Parameters

dry_run – Dry run to test if defaults are set correctly. Defaults to False.

__getitem__(key: str) Union[Callable[[...], Any], qcodes.instrument.parameter.Parameter]

Delegate instrument[‘name’] to parameter or function ‘name’.

__getstate__() None

Prevent pickling instruments, and give a nice error message.

add_function(name: str, **kwargs: Any) None

Bind one Function to this instrument.

Instrument subclasses can call this repeatedly in their __init__ for every real function of the instrument.

This functionality is meant for simple cases, principally things that map to simple commands like *RST (reset) or those with just a few arguments. It requires a fixed argument count, and positional args only. If your case is more complicated, you’re probably better off simply making a new method in your Instrument subclass definition.

Parameters
  • name – How the Function will be stored within instrument.Functions and also how you address it using the shortcut methods: instrument.call(func_name, *args) etc.

  • **kwargs – constructor kwargs for Function

Raises

KeyError – If this instrument already has a function with this name.

add_parameter(name: str, parameter_class: type = <class 'qcodes.instrument.parameter.Parameter'>, **kwargs: Any) None

Bind one Parameter to this instrument.

Instrument subclasses can call this repeatedly in their __init__ for every real parameter of the instrument.

In this sense, parameters are the state variables of the instrument, anything the user can set and/or get.

Parameters
  • name – How the parameter will be stored within instrument.parameters and also how you address it using the shortcut methods: instrument.set(param_name, value) etc.

  • parameter_class – You can construct the parameter out of any class. Default parameter.Parameter.

  • **kwargs – Constructor arguments for parameter_class.

Raises
  • KeyError – If this instrument already has a parameter with this name and the parameter being replaced is not an abstract parameter.

  • ValueError – If there is an existing abstract parameter and the unit of the new parameter is inconsistent with the existing one.

add_submodule(name: str, submodule: Union[InstrumentBase, ChannelList]) None

Bind one submodule to this instrument.

Instrument subclasses can call this repeatedly in their __init__ method for every submodule of the instrument.

Submodules can effectively be considered as instruments within the main instrument, and should at minimum be snapshottable. For example, they can be used to either store logical groupings of parameters, which may or may not be repeated, or channel lists.

Parameters
  • name – How the submodule will be stored within instrument.submodules and also how it can be addressed.

  • submodule – The submodule to be stored.

Raises
  • KeyError – If this instrument already contains a submodule with this name.

  • TypeError – If the submodule that we are trying to add is not an instance of an Metadatable object.

property ancestors: List[qcodes.instrument.base.InstrumentBase]

Returns a list of instruments, starting from the current instrument and following to the parent instrument and the parents parent instrument until the root instrument is reached.

call(func_name: str, *args: Any) Any

Shortcut for calling a function from its name.

Parameters
  • func_name – The name of a function of this instrument.

  • *args – any arguments to the function.

Returns

The return value of the function.

delegate_attr_dicts: List[str] = ['parameters', 'functions', 'submodules']

A list of names (strings) of dictionaries which are (or will be) attributes of self, whose keys should be treated as attributes of self.

delegate_attr_objects: List[str] = []

A list of names (strings) of objects which are (or will be) attributes of self, whose attributes should be passed through to self.

property full_name: str
get(param_name: str) Any

Shortcut for getting a parameter from its name.

Parameters

param_name – The name of a parameter of this instrument.

Returns

The current value of the parameter.

load_metadata(metadata: Dict[Any, Any]) None

Load metadata into this classes metadata dictionary.

Parameters

metadata – Metadata to load.

property name: str

Name of the instrument

property name_parts: List[str]
omit_delegate_attrs: List[str] = []

A list of attribute names (strings) to not delegate to any other dictionary or object.

property parent: Optional[qcodes.instrument.base.InstrumentBase]

Returns the parent instrument. By default this is None. Any SubInstrument should subclass this to return the parent instrument.

print_readable_snapshot(update: bool = False, max_chars: int = 80) None

Prints a readable version of the snapshot. The readable snapshot includes the name, value and unit of each parameter. A convenience function to quickly get an overview of the status of an instrument.

Parameters
  • update – If True, update the state by querying the instrument. If False, just use the latest values in memory. This argument gets passed to the snapshot function.

  • max_chars – the maximum number of characters per line. The readable snapshot will be cropped if this value is exceeded. Defaults to 80 to be consistent with default terminal width.

property root_instrument: qcodes.instrument.base.InstrumentBase
set(param_name: str, value: Any) None

Shortcut for setting a parameter from its name and new value.

Parameters
  • param_name – The name of a parameter of this instrument.

  • value – The new value to set.

property short_name: str

Short name of the instrument

snapshot(update: Optional[bool] = False) Dict[Any, Any]

Decorate a snapshot dictionary with metadata. DO NOT override this method if you want metadata in the snapshot instead, override snapshot_base().

Parameters

update – Passed to snapshot_base.

Returns

Base snapshot.

snapshot_base(update: Optional[bool] = False, params_to_skip_update: Optional[Sequence[str]] = None) Dict[Any, Any]

State of the instrument as a JSON-compatible dict (everything that the custom JSON encoder class qcodes.utils.helpers.NumpyJSONEncoder supports).

Parameters
  • update – If True, update the state by querying the instrument. If None update the state if known to be invalid. If False, just use the latest values in memory and never update state.

  • params_to_skip_update – List of parameter names that will be skipped in update even if update is True. This is useful if you have parameters that are slow to update but can be updated in a different way (as in the qdac). If you want to skip the update of certain parameters in all snapshots, use the snapshot_get attribute of those parameters instead.

Returns

base snapshot

Return type

dict

validate_status(verbose: bool = False) None

Validate the values of all gettable parameters

The validation is done for all parameters that have both a get and set method.

Parameters

verbose – If True, then information about the parameters that are being check is printed.

parameters: Dict[str, _BaseParameter] = {}

All the parameters supported by this instrument. Usually populated via add_parameter().

functions: Dict[str, Function] = {}

All the functions supported by this instrument. Usually populated via add_function().

submodules: Dict[str, Union['InstrumentBase', 'ChannelList']] = {}

All the submodules of this instrument such as channel lists or logical groupings of parameters. Usually populated via add_submodule().

class qcodes.instrument.delegate.delegate_channel_instrument.DelegateChannelInstrument(name: str, station: qcodes.station.Station, channels: str, parameters: Mapping[str, Sequence[str]], initial_values: Optional[Mapping[str, Any]] = None, set_initial_values_on_load: bool = False, **kwargs: Any)[source]

Bases: qcodes.instrument.delegate.delegate_instrument.DelegateInstrument

Delegate instrument that auto generates delegate parameters for a given ChannelList.

Example usage in instrument YAML:

switch:
    type: qcodes.instrument.delegate.DelegateChannelInstrument
    init:
        channels: dac.channels
        parameters:
            state:
            - dac_output
            - smc
            - gnd
            - bus

The above will create a new instrument called switch that generates a method for a delegate parameter:

switch.state()

that returns a named tuple:

state(dac_output=..., smc=..., gnd=..., bus=...)

where the values of each of the tuple items are delegated to the instrument parameters:

dac.dac_output()
dac.smc()
dac.gnd()
dac.bus()
Parameters
  • name – Instrument name

  • station – Station with real instruments to connect to

  • channels – Path to channels, e.g. my_instrument.channels

  • parameters – A mapping from name of a delegate parameter to the sequence of endpoint parameters it connects to. These are auto-generated per channel.

  • initial_values – Default values to set on instrument load. Defaults to None.

  • set_initial_values_on_load – Flag to set defaults on load. Defaults to False.

__getitem__(key: str) Union[Callable[[...], Any], qcodes.instrument.parameter.Parameter]

Delegate instrument[‘name’] to parameter or function ‘name’.

__getstate__() None

Prevent pickling instruments, and give a nice error message.

add_function(name: str, **kwargs: Any) None

Bind one Function to this instrument.

Instrument subclasses can call this repeatedly in their __init__ for every real function of the instrument.

This functionality is meant for simple cases, principally things that map to simple commands like *RST (reset) or those with just a few arguments. It requires a fixed argument count, and positional args only. If your case is more complicated, you’re probably better off simply making a new method in your Instrument subclass definition.

Parameters
  • name – How the Function will be stored within instrument.Functions and also how you address it using the shortcut methods: instrument.call(func_name, *args) etc.

  • **kwargs – constructor kwargs for Function

Raises

KeyError – If this instrument already has a function with this name.

add_parameter(name: str, parameter_class: type = <class 'qcodes.instrument.parameter.Parameter'>, **kwargs: Any) None

Bind one Parameter to this instrument.

Instrument subclasses can call this repeatedly in their __init__ for every real parameter of the instrument.

In this sense, parameters are the state variables of the instrument, anything the user can set and/or get.

Parameters
  • name – How the parameter will be stored within instrument.parameters and also how you address it using the shortcut methods: instrument.set(param_name, value) etc.

  • parameter_class – You can construct the parameter out of any class. Default parameter.Parameter.

  • **kwargs – Constructor arguments for parameter_class.

Raises
  • KeyError – If this instrument already has a parameter with this name and the parameter being replaced is not an abstract parameter.

  • ValueError – If there is an existing abstract parameter and the unit of the new parameter is inconsistent with the existing one.

add_submodule(name: str, submodule: Union[InstrumentBase, ChannelList]) None

Bind one submodule to this instrument.

Instrument subclasses can call this repeatedly in their __init__ method for every submodule of the instrument.

Submodules can effectively be considered as instruments within the main instrument, and should at minimum be snapshottable. For example, they can be used to either store logical groupings of parameters, which may or may not be repeated, or channel lists.

Parameters
  • name – How the submodule will be stored within instrument.submodules and also how it can be addressed.

  • submodule – The submodule to be stored.

Raises
  • KeyError – If this instrument already contains a submodule with this name.

  • TypeError – If the submodule that we are trying to add is not an instance of an Metadatable object.

property ancestors: List[qcodes.instrument.base.InstrumentBase]

Returns a list of instruments, starting from the current instrument and following to the parent instrument and the parents parent instrument until the root instrument is reached.

call(func_name: str, *args: Any) Any

Shortcut for calling a function from its name.

Parameters
  • func_name – The name of a function of this instrument.

  • *args – any arguments to the function.

Returns

The return value of the function.

delegate_attr_dicts: List[str] = ['parameters', 'functions', 'submodules']

A list of names (strings) of dictionaries which are (or will be) attributes of self, whose keys should be treated as attributes of self.

delegate_attr_objects: List[str] = []

A list of names (strings) of objects which are (or will be) attributes of self, whose attributes should be passed through to self.

property full_name: str
get(param_name: str) Any

Shortcut for getting a parameter from its name.

Parameters

param_name – The name of a parameter of this instrument.

Returns

The current value of the parameter.

load_metadata(metadata: Dict[Any, Any]) None

Load metadata into this classes metadata dictionary.

Parameters

metadata – Metadata to load.

property name: str

Name of the instrument

property name_parts: List[str]
omit_delegate_attrs: List[str] = []

A list of attribute names (strings) to not delegate to any other dictionary or object.

param_cls

alias of qcodes.instrument.delegate.grouped_parameter.DelegateGroupParameter

property parent: Optional[qcodes.instrument.base.InstrumentBase]

Returns the parent instrument. By default this is None. Any SubInstrument should subclass this to return the parent instrument.

static parse_instrument_path(parent: Union[qcodes.station.Station, qcodes.instrument.base.InstrumentBase], path: str) Any

Parse a string path and return the object relative to a station or instrument, e.g. “my_instrument.my_param” returns station.my_instrument.my_param

Parameters
  • parent – Measurement station

  • path – Relative path to parse

print_readable_snapshot(update: bool = False, max_chars: int = 80) None

Prints a readable version of the snapshot. The readable snapshot includes the name, value and unit of each parameter. A convenience function to quickly get an overview of the status of an instrument.

Parameters
  • update – If True, update the state by querying the instrument. If False, just use the latest values in memory. This argument gets passed to the snapshot function.

  • max_chars – the maximum number of characters per line. The readable snapshot will be cropped if this value is exceeded. Defaults to 80 to be consistent with default terminal width.

property root_instrument: qcodes.instrument.base.InstrumentBase
set(param_name: str, value: Any) None

Shortcut for setting a parameter from its name and new value.

Parameters
  • param_name – The name of a parameter of this instrument.

  • value – The new value to set.

set_initial_values(dry_run: bool = False) None

Set parameter initial values on delegate instrument

Parameters

dry_run – Dry run to test if defaults are set correctly. Defaults to False.

property short_name: str

Short name of the instrument

snapshot(update: Optional[bool] = False) Dict[Any, Any]

Decorate a snapshot dictionary with metadata. DO NOT override this method if you want metadata in the snapshot instead, override snapshot_base().

Parameters

update – Passed to snapshot_base.

Returns

Base snapshot.

snapshot_base(update: Optional[bool] = False, params_to_skip_update: Optional[Sequence[str]] = None) Dict[Any, Any]

State of the instrument as a JSON-compatible dict (everything that the custom JSON encoder class qcodes.utils.helpers.NumpyJSONEncoder supports).

Parameters
  • update – If True, update the state by querying the instrument. If None update the state if known to be invalid. If False, just use the latest values in memory and never update state.

  • params_to_skip_update – List of parameter names that will be skipped in update even if update is True. This is useful if you have parameters that are slow to update but can be updated in a different way (as in the qdac). If you want to skip the update of certain parameters in all snapshots, use the snapshot_get attribute of those parameters instead.

Returns

base snapshot

Return type

dict

validate_status(verbose: bool = False) None

Validate the values of all gettable parameters

The validation is done for all parameters that have both a get and set method.

Parameters

verbose – If True, then information about the parameters that are being check is printed.

parameters: Dict[str, _BaseParameter] = {}

All the parameters supported by this instrument. Usually populated via add_parameter().

functions: Dict[str, Function] = {}

All the functions supported by this instrument. Usually populated via add_function().

submodules: Dict[str, Union['InstrumentBase', 'ChannelList']] = {}

All the submodules of this instrument such as channel lists or logical groupings of parameters. Usually populated via add_submodule().

class qcodes.instrument.delegate.grouped_parameter.DelegateGroup(name: str, parameters: Sequence[qcodes.instrument.delegate.grouped_parameter.DelegateGroupParameter], parameter_names: Optional[Iterable[str]] = None, setter: Optional[Callable[[...], Any]] = None, getter: Optional[Callable[[...], Any]] = None, formatter: Optional[Callable[[...], Any]] = None, **kwargs: Any)[source]

Bases: qcodes.instrument.group_parameter.Group

The DelegateGroup combines DelegateParameter s that are to be gotten or set using one GroupedParameter. Each DelegateParameter maps to one source parameter that is individually set or gotten on an instrument. These parameters can originate from the same or different instruments.

The class DelegateGroup is used within the GroupedParameter class in order to get and set the DelegateParameter s either via their default get and set methods or via a custom get or set method.

The value to be set can be passed to the set method either via a dictionary, where the keys are the names of the DelegateParameter s contained in the DelegateGroup, or a single value, if a custom setter is defined or if the group only contains a single DelegateParameter.

The value returned by the get method is passed through a formatter. By default, the formatter returns the DelegateParameter values in a namedtuple, where the keys are the names of the DelegateParameter s. In the special case where the DelegateGroup only contains one DelegateParameter, the formatter simply returns the individual value. Optionally, the formatter can be customized and specified via the constructor. The formatter takes as input the values of the DelegateParameter s as positional arguments in the order at which the DelegateParameter s are specified.

Parameters
  • name – Name of the DelegateGroup

  • parameters – DelegateParameters to group together

  • parameter_names – Optional names of parameters, defaults to the parameter name attributes

  • setter – Optional function to call for setting the grouped parameters, should take one argument value. Defaults to set_parameters(), which sets each parameter using its .set() method.

  • getter – Optional function to call for getting the grouped parameters. Defaults to .get_parameters(), which runs the get() method for each parameter.

  • formatter – Optional formatter for value returned by get_parameters(), defaults to a namedtuple with the parameter names as keys.

set(value: Union[Any, Mapping[str, Any]]) None[source]
get() Any[source]
get_parameters() Any[source]
property source_parameters: Tuple[Optional[qcodes.instrument.parameter.Parameter], ...]

Get source parameters of each DelegateParameter

property instrument: Optional[qcodes.instrument.base.InstrumentBase]

The root_instrument that this parameter belongs to.

property parameters: OrderedDict[str, GroupParameter]

All parameters in this group as a dict from parameter name to Parameter

set_parameters(parameters_dict: Mapping[str, Any]) None

Sets the value of one or more parameters within a group to the given values by calling the set_cmd while updating rest.

Parameters
  • parameters_dict – The dictionary of one or more parameters within

  • set. (the group with the corresponding values to be) –

update() None

Update the values of all the parameters within the group by calling the get_cmd.

class qcodes.instrument.delegate.grouped_parameter.DelegateGroupParameter(name: str, source: Optional[qcodes.instrument.parameter.Parameter], instrument: Optional[InstrumentBase] = None, initial_value: Optional[Union[float, str]] = None, **kwargs: Any)[source]

Bases: qcodes.instrument.parameter.DelegateParameter, qcodes.instrument.group_parameter.GroupParameter

__getitem__(keys: Any) qcodes.instrument.sweep_values.SweepFixedValues

Slice a Parameter to get a SweepValues object to iterate over during a sweep

__str__() str

Include the instrument name with the Parameter name if possible.

property abstract: Optional[bool]
property full_name: str

Name of the parameter including the name of the instrument and submodule that the parameter may be bound to. The names are separated by underscores, like this: instrument_submodule_parameter.

get_ramp_values(value: Union[float, Sized], step: Optional[float] = None) Sequence[Union[float, Sized]]

Return values to sweep from current value to target value. This method can be overridden to have a custom sweep behaviour. It can even be overridden by a generator.

Parameters
  • value – target value

  • step – maximum step size

Returns

List of stepped values, including target value.

get_raw() Any

get_raw is called to perform the actual data acquisition from the instrument. This method should either be overwritten to perform the desired operation or alternatively for Parameter a suitable method is automatically generated if get_cmd is supplied to the parameter constructor. The method is automatically wrapped to provide a get method on the parameter instance.

property gettable: bool

Is it allowed to call get on this parameter?

property group: Optional[qcodes.instrument.group_parameter.Group]

The group that this parameter belongs to.

increment(value: Any) None

Increment the parameter with a value

Parameters

value – Value to be added to the parameter.

property instrument: Optional[InstrumentBase]

Return the first instrument that this parameter is bound to. E.g if this is bound to a channel it will return the channel and not the instrument that the channel is bound too. Use root_instrument() to get the real instrument.

property inter_delay: float

Delay time between consecutive set operations. The actual time will not be shorter than this, but may be longer if the underlying set call takes longer.

Typically used in conjunction with step to create an effective ramp rate, but can also be used without a step to enforce a delay between sets.

Getter

Returns the current inter_delay.

Setter

Sets the value of the inter_delay.

Raises
load_metadata(metadata: Dict[Any, Any]) None

Load metadata into this classes metadata dictionary.

Parameters

metadata – Metadata to load.

property name: str

Name of the parameter. This is identical to short_name().

property name_parts: List[str]

List of the parts that make up the full name of this parameter

property post_delay: float

Delay time after start of set operation, for each set. The actual time will not be shorter than this, but may be longer if the underlying set call takes longer.

Typically used in conjunction with step to create an effective ramp rate, but can also be used without a step to enforce a delay after every set. One might think of post_delay as how long a set operation is supposed to take. For example, there might be an instrument that needs extra time after setting a parameter although the command for setting the parameter returns quickly.

Getter

Returns the current post_delay.

Setter

Sets the value of the post_delay.

Raises
property raw_value: Any

Note that this property will be deprecated soon. Use cache.raw_value instead.

Represents the cached raw value of the parameter.

Getter

Returns the cached raw value of the parameter.

restore_at_exit(allow_changes: bool = True) qcodes.instrument.parameter._SetParamContext

Use a context manager to restore the value of a parameter after a with block.

By default, the parameter value may be changed inside the block, but this can be prevented with allow_changes=False. This can be useful, for example, for debugging a complex measurement that unintentionally modifies a parameter.

Example

>>> p = Parameter("p", set_cmd=None, get_cmd=None)
>>> p.set(2)
>>> with p.restore_at_exit():
...     p.set(3)
...     print(f"value inside with block: {p.get()}")  # prints 3
>>> print(f"value after with block: {p.get()}")  # prints 2
>>> with p.restore_at_exit(allow_changes=False):
...     p.set(5)  # raises an exception
property root_instrument: Optional[InstrumentBase]

Return the fundamental instrument that this parameter belongs too. E.g if the parameter is bound to a channel this will return the fundamental instrument that that channel belongs to. Use instrument() to get the channel.

set_raw(value: Any) None

set_raw is called to perform the actual setting of a parameter on the instrument. This method should either be overwritten to perform the desired operation or alternatively for Parameter a suitable method is automatically generated if set_cmd is supplied to the parameter constructor. The method is automatically wrapped to provide a set method on the parameter instance.

set_to(value: Any, allow_changes: bool = False) qcodes.instrument.parameter._SetParamContext

Use a context manager to temporarily set a parameter to a value. By default, the parameter value cannot be changed inside the context. This may be overridden with allow_changes=True.

Examples

>>> from qcodes import Parameter
>>> p = Parameter("p", set_cmd=None, get_cmd=None)
>>> p.set(2)
>>> with p.set_to(3):
...     print(f"p value in with block {p.get()}")  # prints 3
...     p.set(5)  # raises an exception
>>> print(f"p value outside with block {p.get()}")  # prints 2
>>> with p.set_to(3, allow_changes=True):
...     p.set(5)  # now this works
>>> print(f"value after second block: {p.get()}")  # still prints 2
property settable: bool

Is it allowed to call set on this parameter?

property short_name: str

Short name of the parameter. This is without the name of the instrument or submodule that the parameter may be bound to. For full name refer to full_name().

snapshot(update: Optional[bool] = False) Dict[Any, Any]

Decorate a snapshot dictionary with metadata. DO NOT override this method if you want metadata in the snapshot instead, override snapshot_base().

Parameters

update – Passed to snapshot_base.

Returns

Base snapshot.

snapshot_base(update: Optional[bool] = True, params_to_skip_update: Optional[Sequence[str]] = None) Dict[Any, Any]

State of the parameter as a JSON-compatible dict (everything that the custom JSON encoder class qcodes.utils.helpers.NumpyJSONEncoder supports).

If the parameter has been initiated with snapshot_value=False, the snapshot will NOT include the value and raw_value of the parameter.

Parameters
  • update – If True, update the state by calling parameter.get() unless snapshot_get of the parameter is False. If update is None, use the current value from the cache unless the cache is invalid. If False, never call parameter.get().

  • params_to_skip_update – No effect but may be passed from superclass

Returns

base snapshot

property snapshot_value: bool

If True the value of the parameter will be included in the snapshot.

property source: Optional[qcodes.instrument.parameter.Parameter]

The source parameter that this DelegateParameter is bound to or None if this DelegateParameter is unbound.

Getter

Returns the current source.

Setter

Sets the source.

property step: Optional[float]

Stepsize that this Parameter uses during set operation. Stepsize must be a positive number or None. If step is a positive number, this is the maximum value change allowed in one hardware call, so a single set can result in many calls to the hardware if the starting value is far from the target. All but the final change will attempt to change by +/- step exactly. If step is None stepping will not be used.

Getter

Returns the current stepsize.

Setter

Sets the value of the step.

Raises
  • TypeError – if step is set to not numeric or None

  • ValueError – if step is set to negative

  • TypeError – if step is set to not integer or None for an integer parameter

  • TypeError – if step is set to not a number on None

sweep(start: float, stop: float, step: Optional[float] = None, num: Optional[int] = None) qcodes.instrument.sweep_values.SweepFixedValues

Create a collection of parameter values to be iterated over. Requires start and stop and (step or num) The sign of step is not relevant.

Parameters
  • start – The starting value of the sequence.

  • stop – The end value of the sequence.

  • step – Spacing between values.

  • num – Number of values to generate.

Returns

Collection of parameter values to be iterated over.

Return type

SweepFixedValues

Examples

>>> sweep(0, 10, num=5)
 [0.0, 2.5, 5.0, 7.5, 10.0]
>>> sweep(5, 10, step=1)
[5.0, 6.0, 7.0, 8.0, 9.0, 10.0]
>>> sweep(15, 10.5, step=1.5)
>[15.0, 13.5, 12.0, 10.5]
property underlying_instrument: Optional[InstrumentBase]

Returns an instance of the underlying hardware instrument that this parameter communicates with, per this parameter’s implementation.

This is useful in the case where a parameter does not belongs to an instrument instance that represents a real hardware instrument but actually uses a real hardware instrument in its implementation (e.g. via calls to one or more parameters of that real hardware instrument). This is also useful when a parameter does belong to an instrument instance but that instance does not represent the real hardware instrument that the parameter interacts with: hence root_instrument of the parameter cannot be the hardware_instrument, however underlying_instrument can be implemented to return the hardware_instrument.

By default it returns the root_instrument of the parameter.

validate(value: Any) None

Validate the value supplied.

Parameters

value – value to validate

Raises
  • TypeError – If the value is of the wrong type.

  • ValueError – If the value is outside the bounds specified by the validator.

label: str = ()

Label of the data used for plots etc.

unit = ()

The unit of measure. Use '' for unitless.

class qcodes.instrument.delegate.grouped_parameter.GroupedParameter(name: str, group: qcodes.instrument.delegate.grouped_parameter.DelegateGroup, unit: Optional[str] = None, label: Optional[str] = None, **kwargs: Any)[source]

Bases: qcodes.instrument.parameter._BaseParameter

The GroupedParameter wraps one or more DelegateParameter s, such that those parameters can be accessed as if they were one parameter.

The GroupedParameter uses a DelegateGroup to keep track of the DelegateParameter s. Mainly, this class is a thin wrapper around the DelegateGroup, and mainly exists in order to allow for it to be used as a _BaseParameter.

This class can be seen as the opposite of a GroupParameter, which is a class to create parameters that are set with a single get and set string command on the same instrument but need to be accessed separately. In contrast, the GroupedParameter allows grouped access to parameters that are normally separate, and can be associated with different instruments.

Parameters
  • name – Grouped parameter name.

  • group – Group that contains the target parameter(s).

  • unit – The unit of measure. Use '' for unitless.

  • label – Optional label, defaults to parameter name.

  • method (default set) –

property group: qcodes.instrument.delegate.grouped_parameter.DelegateGroup

The group that contains the target parameters.

property parameters: Dict[str, qcodes.instrument.group_parameter.GroupParameter]

Get delegate parameters wrapped by this GroupedParameter

property source_parameters: Tuple[Optional[qcodes.instrument.parameter.Parameter], ...]

Get source parameters of each DelegateParameter

get_raw() Union[Any, Mapping[str, Any]][source]

Get parameter raw value

__str__() str

Include the instrument name with the Parameter name if possible.

property abstract: Optional[bool]
property full_name: str

Name of the parameter including the name of the instrument and submodule that the parameter may be bound to. The names are separated by underscores, like this: instrument_submodule_parameter.

get_ramp_values(value: Union[float, Sized], step: Optional[float] = None) Sequence[Union[float, Sized]]

Return values to sweep from current value to target value. This method can be overridden to have a custom sweep behaviour. It can even be overridden by a generator.

Parameters
  • value – target value

  • step – maximum step size

Returns

List of stepped values, including target value.

property gettable: bool

Is it allowed to call get on this parameter?

property instrument: Optional[InstrumentBase]

Return the first instrument that this parameter is bound to. E.g if this is bound to a channel it will return the channel and not the instrument that the channel is bound too. Use root_instrument() to get the real instrument.

property inter_delay: float

Delay time between consecutive set operations. The actual time will not be shorter than this, but may be longer if the underlying set call takes longer.

Typically used in conjunction with step to create an effective ramp rate, but can also be used without a step to enforce a delay between sets.

Getter

Returns the current inter_delay.

Setter

Sets the value of the inter_delay.

Raises
load_metadata(metadata: Dict[Any, Any]) None

Load metadata into this classes metadata dictionary.

Parameters

metadata – Metadata to load.

property name: str

Name of the parameter. This is identical to short_name().

property name_parts: List[str]

List of the parts that make up the full name of this parameter

property post_delay: float

Delay time after start of set operation, for each set. The actual time will not be shorter than this, but may be longer if the underlying set call takes longer.

Typically used in conjunction with step to create an effective ramp rate, but can also be used without a step to enforce a delay after every set. One might think of post_delay as how long a set operation is supposed to take. For example, there might be an instrument that needs extra time after setting a parameter although the command for setting the parameter returns quickly.

Getter

Returns the current post_delay.

Setter

Sets the value of the post_delay.

Raises
property raw_value: Any

Note that this property will be deprecated soon. Use cache.raw_value instead.

Represents the cached raw value of the parameter.

Getter

Returns the cached raw value of the parameter.

restore_at_exit(allow_changes: bool = True) qcodes.instrument.parameter._SetParamContext

Use a context manager to restore the value of a parameter after a with block.

By default, the parameter value may be changed inside the block, but this can be prevented with allow_changes=False. This can be useful, for example, for debugging a complex measurement that unintentionally modifies a parameter.

Example

>>> p = Parameter("p", set_cmd=None, get_cmd=None)
>>> p.set(2)
>>> with p.restore_at_exit():
...     p.set(3)
...     print(f"value inside with block: {p.get()}")  # prints 3
>>> print(f"value after with block: {p.get()}")  # prints 2
>>> with p.restore_at_exit(allow_changes=False):
...     p.set(5)  # raises an exception
property root_instrument: Optional[InstrumentBase]

Return the fundamental instrument that this parameter belongs too. E.g if the parameter is bound to a channel this will return the fundamental instrument that that channel belongs to. Use instrument() to get the channel.

set_raw(value: Union[Any, Mapping[str, Any]]) None[source]

Set parameter raw value

Parameters

value – Parameter value to set

Returns

Returns the parameter value

Return type

float

set_to(value: Any, allow_changes: bool = False) qcodes.instrument.parameter._SetParamContext

Use a context manager to temporarily set a parameter to a value. By default, the parameter value cannot be changed inside the context. This may be overridden with allow_changes=True.

Examples

>>> from qcodes import Parameter
>>> p = Parameter("p", set_cmd=None, get_cmd=None)
>>> p.set(2)
>>> with p.set_to(3):
...     print(f"p value in with block {p.get()}")  # prints 3
...     p.set(5)  # raises an exception
>>> print(f"p value outside with block {p.get()}")  # prints 2
>>> with p.set_to(3, allow_changes=True):
...     p.set(5)  # now this works
>>> print(f"value after second block: {p.get()}")  # still prints 2
property settable: bool

Is it allowed to call set on this parameter?

property short_name: str

Short name of the parameter. This is without the name of the instrument or submodule that the parameter may be bound to. For full name refer to full_name().

snapshot(update: Optional[bool] = False) Dict[Any, Any]

Decorate a snapshot dictionary with metadata. DO NOT override this method if you want metadata in the snapshot instead, override snapshot_base().

Parameters

update – Passed to snapshot_base.

Returns

Base snapshot.

snapshot_base(update: Optional[bool] = True, params_to_skip_update: Optional[Sequence[str]] = None) Dict[Any, Any]

State of the parameter as a JSON-compatible dict (everything that the custom JSON encoder class qcodes.utils.helpers.NumpyJSONEncoder supports).

If the parameter has been initiated with snapshot_value=False, the snapshot will NOT include the value and raw_value of the parameter.

Parameters
  • update – If True, update the state by calling parameter.get() unless snapshot_get of the parameter is False. If update is None, use the current value from the cache unless the cache is invalid. If False, never call parameter.get().

  • params_to_skip_update – No effect but may be passed from superclass

Returns

base snapshot

property snapshot_value: bool

If True the value of the parameter will be included in the snapshot.

property step: Optional[float]

Stepsize that this Parameter uses during set operation. Stepsize must be a positive number or None. If step is a positive number, this is the maximum value change allowed in one hardware call, so a single set can result in many calls to the hardware if the starting value is far from the target. All but the final change will attempt to change by +/- step exactly. If step is None stepping will not be used.

Getter

Returns the current stepsize.

Setter

Sets the value of the step.

Raises
  • TypeError – if step is set to not numeric or None

  • ValueError – if step is set to negative

  • TypeError – if step is set to not integer or None for an integer parameter

  • TypeError – if step is set to not a number on None

property underlying_instrument: Optional[InstrumentBase]

Returns an instance of the underlying hardware instrument that this parameter communicates with, per this parameter’s implementation.

This is useful in the case where a parameter does not belongs to an instrument instance that represents a real hardware instrument but actually uses a real hardware instrument in its implementation (e.g. via calls to one or more parameters of that real hardware instrument). This is also useful when a parameter does belong to an instrument instance but that instance does not represent the real hardware instrument that the parameter interacts with: hence root_instrument of the parameter cannot be the hardware_instrument, however underlying_instrument can be implemented to return the hardware_instrument.

By default it returns the root_instrument of the parameter.

validate(value: Any) None

Validate the value supplied.

Parameters

value – value to validate

Raises
  • TypeError – If the value is of the wrong type.

  • ValueError – If the value is outside the bounds specified by the validator.

class qcodes.instrument.delegate.instrument_group.InstrumentGroup(name: str, station: Station, submodules_type: str, submodules: Mapping[str, Mapping[str, List[str]]], initial_values: Mapping[str, Mapping[str, Any]], set_initial_values_on_load: bool = False, **kwargs: Any)[source]

Bases: qcodes.instrument.base.InstrumentBase

InstrumentGroup is an instrument driver to represent a series of instruments that are grouped together. This instrument is mainly used as a wrapper for sub instruments/submodules and particularly built for use with grouping multiple DelegateInstrument s.

Parameters
  • name – Name referring to this group of items

  • station – Measurement station with real instruments

  • submodules_type – Class to use for creating the instruments.

  • submodules – A mapping between an instrument name and the values passed to the constructor of the class specified by submodules_type.

  • initial_values – A mapping between the names of parameters and initial values to set on those parameters when loading this instrument.

  • set_initial_values_on_load – Set default values on load. Defaults to False.

__getitem__(key: str) Union[Callable[[...], Any], qcodes.instrument.parameter.Parameter]

Delegate instrument[‘name’] to parameter or function ‘name’.

__getstate__() None

Prevent pickling instruments, and give a nice error message.

add_function(name: str, **kwargs: Any) None

Bind one Function to this instrument.

Instrument subclasses can call this repeatedly in their __init__ for every real function of the instrument.

This functionality is meant for simple cases, principally things that map to simple commands like *RST (reset) or those with just a few arguments. It requires a fixed argument count, and positional args only. If your case is more complicated, you’re probably better off simply making a new method in your Instrument subclass definition.

Parameters
  • name – How the Function will be stored within instrument.Functions and also how you address it using the shortcut methods: instrument.call(func_name, *args) etc.

  • **kwargs – constructor kwargs for Function

Raises

KeyError – If this instrument already has a function with this name.

add_parameter(name: str, parameter_class: type = <class 'qcodes.instrument.parameter.Parameter'>, **kwargs: Any) None

Bind one Parameter to this instrument.

Instrument subclasses can call this repeatedly in their __init__ for every real parameter of the instrument.

In this sense, parameters are the state variables of the instrument, anything the user can set and/or get.

Parameters
  • name – How the parameter will be stored within instrument.parameters and also how you address it using the shortcut methods: instrument.set(param_name, value) etc.

  • parameter_class – You can construct the parameter out of any class. Default parameter.Parameter.

  • **kwargs – Constructor arguments for parameter_class.

Raises
  • KeyError – If this instrument already has a parameter with this name and the parameter being replaced is not an abstract parameter.

  • ValueError – If there is an existing abstract parameter and the unit of the new parameter is inconsistent with the existing one.

add_submodule(name: str, submodule: Union[InstrumentBase, ChannelList]) None

Bind one submodule to this instrument.

Instrument subclasses can call this repeatedly in their __init__ method for every submodule of the instrument.

Submodules can effectively be considered as instruments within the main instrument, and should at minimum be snapshottable. For example, they can be used to either store logical groupings of parameters, which may or may not be repeated, or channel lists.

Parameters
  • name – How the submodule will be stored within instrument.submodules and also how it can be addressed.

  • submodule – The submodule to be stored.

Raises
  • KeyError – If this instrument already contains a submodule with this name.

  • TypeError – If the submodule that we are trying to add is not an instance of an Metadatable object.

property ancestors: List[qcodes.instrument.base.InstrumentBase]

Returns a list of instruments, starting from the current instrument and following to the parent instrument and the parents parent instrument until the root instrument is reached.

call(func_name: str, *args: Any) Any

Shortcut for calling a function from its name.

Parameters
  • func_name – The name of a function of this instrument.

  • *args – any arguments to the function.

Returns

The return value of the function.

delegate_attr_dicts: List[str] = ['parameters', 'functions', 'submodules']

A list of names (strings) of dictionaries which are (or will be) attributes of self, whose keys should be treated as attributes of self.

delegate_attr_objects: List[str] = []

A list of names (strings) of objects which are (or will be) attributes of self, whose attributes should be passed through to self.

property full_name: str
get(param_name: str) Any

Shortcut for getting a parameter from its name.

Parameters

param_name – The name of a parameter of this instrument.

Returns

The current value of the parameter.

load_metadata(metadata: Dict[Any, Any]) None

Load metadata into this classes metadata dictionary.

Parameters

metadata – Metadata to load.

property name: str

Name of the instrument

property name_parts: List[str]
omit_delegate_attrs: List[str] = []

A list of attribute names (strings) to not delegate to any other dictionary or object.

property parent: Optional[qcodes.instrument.base.InstrumentBase]

Returns the parent instrument. By default this is None. Any SubInstrument should subclass this to return the parent instrument.

print_readable_snapshot(update: bool = False, max_chars: int = 80) None

Prints a readable version of the snapshot. The readable snapshot includes the name, value and unit of each parameter. A convenience function to quickly get an overview of the status of an instrument.

Parameters
  • update – If True, update the state by querying the instrument. If False, just use the latest values in memory. This argument gets passed to the snapshot function.

  • max_chars – the maximum number of characters per line. The readable snapshot will be cropped if this value is exceeded. Defaults to 80 to be consistent with default terminal width.

property root_instrument: qcodes.instrument.base.InstrumentBase
set(param_name: str, value: Any) None

Shortcut for setting a parameter from its name and new value.

Parameters
  • param_name – The name of a parameter of this instrument.

  • value – The new value to set.

property short_name: str

Short name of the instrument

snapshot(update: Optional[bool] = False) Dict[Any, Any]

Decorate a snapshot dictionary with metadata. DO NOT override this method if you want metadata in the snapshot instead, override snapshot_base().

Parameters

update – Passed to snapshot_base.

Returns

Base snapshot.

snapshot_base(update: Optional[bool] = False, params_to_skip_update: Optional[Sequence[str]] = None) Dict[Any, Any]

State of the instrument as a JSON-compatible dict (everything that the custom JSON encoder class qcodes.utils.helpers.NumpyJSONEncoder supports).

Parameters
  • update – If True, update the state by querying the instrument. If None update the state if known to be invalid. If False, just use the latest values in memory and never update state.

  • params_to_skip_update – List of parameter names that will be skipped in update even if update is True. This is useful if you have parameters that are slow to update but can be updated in a different way (as in the qdac). If you want to skip the update of certain parameters in all snapshots, use the snapshot_get attribute of those parameters instead.

Returns

base snapshot

Return type

dict

validate_status(verbose: bool = False) None

Validate the values of all gettable parameters

The validation is done for all parameters that have both a get and set method.

Parameters

verbose – If True, then information about the parameters that are being check is printed.

parameters: Dict[str, _BaseParameter] = {}

All the parameters supported by this instrument. Usually populated via add_parameter().

functions: Dict[str, Function] = {}

All the functions supported by this instrument. Usually populated via add_function().

submodules: Dict[str, Union['InstrumentBase', 'ChannelList']] = {}

All the submodules of this instrument such as channel lists or logical groupings of parameters. Usually populated via add_submodule().