qcodes.instrument.base
Instrument base class.
- class qcodes.instrument.base.Instrument(*args: Any, **kwargs: Any)[source]
Bases:
qcodes.instrument.base.InstrumentBase
Base class for all QCodes instruments.
- Parameters
name – an identifier for this instrument, particularly for attaching it to a Station.
metadata – additional static metadata to add to this instrument’s JSON snapshot.
- get_idn() Dict[str, Optional[str]] [source]
Parse a standard VISA
*IDN?
response into an ID dict.Even though this is the VISA standard, it applies to various other types as well, such as IPInstruments, so it is included here in the Instrument base class.
Override this if your instrument does not support
*IDN?
or returns a nonstandard IDN string. This string is supposed to be a comma-separated list of vendor, model, serial, and firmware, but semicolon and colon are also common separators so we accept them here as well.- Returns
A dict containing vendor, model, serial, and firmware.
- connect_message(idn_param: str = 'IDN', begin_time: Optional[float] = None) None [source]
Print a standard message on initial connection to an instrument.
- Parameters
idn_param – Name of parameter that returns ID dict. Default
IDN
.begin_time –
time.time()
when init started. Default isself._t0
, set at start ofInstrument.__init__
.
- close() None [source]
Irreversibly stop this instrument and free its resources.
Subclasses should override this if they have other specific resources to close.
- classmethod close_all() None [source]
Try to close all instruments registered in
_all_instruments
This is handy for use with atexit to ensure that all instruments are closed when a python session is closed.Examples
>>> atexit.register(qc.Instrument.close_all())
- classmethod record_instance(instance: qcodes.instrument.base.Instrument) None [source]
Record (a weak ref to) an instance in a class’s instance list.
Also records the instance in list of all instruments, and verifies that there are no other instruments with the same name.
This method is called after initialization of the instrument is completed.
- Parameters
instance – Instance to record.
- Raises
KeyError – If another instance with the same name is already present.
- classmethod instances() List[qcodes.instrument.base.Instrument] [source]
Get all currently defined instances of this instrument class.
You can use this to get the objects back if you lose track of them, and it’s also used by the test system to find objects to test against.
- Returns
A list of instances.
- classmethod remove_instance(instance: qcodes.instrument.base.Instrument) None [source]
Remove a particular instance from the record.
- Parameters
instance – The instance to remove
- classmethod find_instrument(name: str, instrument_class: Optional[Type[qcodes.instrument.base.T]] = None) qcodes.instrument.base.T [source]
Find an existing instrument by name.
- Parameters
name – Name of the instrument.
instrument_class – The type of instrument you are looking for.
- Returns
The instrument found.
- Raises
- static exist(name: str, instrument_class: Optional[type] = None) bool [source]
Check if an instrument with a given names exists (i.e. is already instantiated).
- Parameters
name – Name of the instrument.
instrument_class – The type of instrument you are looking for.
- static is_valid(instr_instance: qcodes.instrument.base.Instrument) bool [source]
Check if a given instance of an instrument is valid: if an instrument has been closed, its instance is not longer a “valid” instrument.
- Parameters
instr_instance – Instance of an Instrument class or its subclass.
- __getitem__(key: str) Union[Callable[[...], Any], qcodes.instrument.parameter.Parameter]
Delegate instrument[‘name’] to parameter or function ‘name’.
- 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 yourInstrument
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[InstrumentModule, ChannelTuple]) 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. They should either be an instance of an
InstrumentModule
or aChannelTuple
.- 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
- 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 ofself
.
- 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 toself
.
- 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.
- invalidate_cache() None
Invalidate the cache of all parameters on the instrument. Calling this method will recursively mark the cache of all parameters on the instrument and any parameter on instrument modules as invalid.
This is useful if you have performed manual operations (e.g. using the frontpanel) which changes the state of the instrument outside QCoDeS.
This in turn means that the next snapshot of the instrument will trigger a (potentially slow) reread of all parameters of the instrument if you pass update=None to snapshot.
- load_metadata(metadata: Mapping[str, Any]) None
Load metadata into this classes metadata dictionary.
- Parameters
metadata – Metadata to load.
- property name: str
Name of the instrument This is equivalent to full_name for backwards compatibility.
- 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. IfFalse
, 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.
- 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. IfFalse
, 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
- 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.
- write(cmd: str) None [source]
Write a command string with NO response to the hardware.
Subclasses that transform
cmd
should override this method, and in it callsuper().write(new_cmd)
. Subclasses that define a new hardware communication should instead overridewrite_raw
.- Parameters
cmd – The string to send to the instrument.
- Raises
Exception – Wraps any underlying exception with extra context, including the command and the instrument.
- 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['InstrumentModule', 'ChannelTuple']] = {}
All the submodules of this instrument such as channel lists or logical groupings of parameters. Usually populated via
add_submodule()
.
- instrument_modules: Dict[str, 'InstrumentModule'] = {}
All the instrument_modules of this instrument Usually populated via
add_submodule()
.
- write_raw(cmd: str) None [source]
Low level method to write a command string to the hardware.
Subclasses that define a new hardware communication should override this method. Subclasses that transform
cmd
should instead overridewrite
.- Parameters
cmd – The string to send to the instrument.
- ask(cmd: str) str [source]
Write a command string to the hardware and return a response.
Subclasses that transform
cmd
should override this method, and in it callsuper().ask(new_cmd)
. Subclasses that define a new hardware communication should instead overrideask_raw
.- Parameters
cmd – The string to send to the instrument.
- Returns
response
- Raises
Exception – Wraps any underlying exception with extra context, including the command and the instrument.
- class qcodes.instrument.base.InstrumentBase(name: str, metadata: Optional[Mapping[Any, Any]] = None)[source]
Bases:
qcodes.utils.metadata.Metadatable
,qcodes.utils.helpers.DelegateAttributes
Base class for all QCodes instruments and instrument channels
- Parameters
name – an identifier for this instrument, particularly for attaching it to a Station.
metadata – additional static metadata to add to this instrument’s JSON snapshot.
- 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['InstrumentModule', 'ChannelTuple']] = {}
All the submodules of this instrument such as channel lists or logical groupings of parameters. Usually populated via
add_submodule()
.
- instrument_modules: Dict[str, 'InstrumentModule'] = {}
All the instrument_modules of this instrument Usually populated via
add_submodule()
.
- add_parameter(name: str, parameter_class: type = <class 'qcodes.instrument.parameter.Parameter'>, **kwargs: Any) None [source]
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_function(name: str, **kwargs: Any) None [source]
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 yourInstrument
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_submodule(name: str, submodule: Union[InstrumentModule, ChannelTuple]) None [source]
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. They should either be an instance of an
InstrumentModule
or aChannelTuple
.- 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
- snapshot_base(update: Optional[bool] = False, params_to_skip_update: Optional[Sequence[str]] = None) Dict[Any, Any] [source]
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. IfFalse
, 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
- print_readable_snapshot(update: bool = False, max_chars: int = 80) None [source]
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. IfFalse
, 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.
- invalidate_cache() None [source]
Invalidate the cache of all parameters on the instrument. Calling this method will recursively mark the cache of all parameters on the instrument and any parameter on instrument modules as invalid.
This is useful if you have performed manual operations (e.g. using the frontpanel) which changes the state of the instrument outside QCoDeS.
This in turn means that the next snapshot of the instrument will trigger a (potentially slow) reread of all parameters of the instrument if you pass update=None to snapshot.
- 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.
- 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.
- property root_instrument: qcodes.instrument.base.InstrumentBase
- property name: str
Name of the instrument This is equivalent to full_name for backwards compatibility.
- 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 ofself
.
- __getitem__(key: str) Union[Callable[[...], Any], qcodes.instrument.parameter.Parameter] [source]
Delegate instrument[‘name’] to parameter or function ‘name’.
- set(param_name: str, value: Any) None [source]
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.
- get(param_name: str) Any [source]
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.
- call(func_name: str, *args: Any) Any [source]
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.
- validate_status(verbose: bool = False) None [source]
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.
- 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 toself
.
- load_metadata(metadata: Mapping[str, Any]) None
Load metadata into this classes metadata dictionary.
- Parameters
metadata – Metadata to load.
- omit_delegate_attrs: List[str] = []
A list of attribute names (strings) to not delegate to any other dictionary or object.
- 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.
- class qcodes.instrument.base.InstrumentMeta(name, bases, namespace, **kwargs)[source]
Bases:
abc.ABCMeta
Metaclass used to customize Instrument creation. We want to register the instance iff __init__ successfully runs, however we can only do this if we customize the instance initialization process, otherwise there is no way to run register_instance after __init__ but before the created instance is returned to the caller.
Instead we use the fact that __new__ and __init__ are called inside type.__call__ (https://github.com/python/cpython/blob/main/Objects/typeobject.c#L1077, https://github.com/python/typeshed/blob/master/stdlib/builtins.pyi#L156) which we will overload to insert our own custom code AFTER __init__ is complete. Note this is part of the spec and will work in alternate python implementations like pypy too.
We inherit from ABCMeta rather than type for backwards compatibility reasons. There may be instrument interfaces that are defined in terms of an ABC. Inheriting directly from type here would then give TypeError: metaclass conflict: the metaclass of a derived class must be a (non-strict) subclass of the metaclasses of all its bases for a class that inherits from ABC
- __call__(*args: Any, **kwargs: Any) Any [source]
Overloads type.__call__ to add code that runs only if __init__ completes successfully.
- __instancecheck__(instance)
Override for isinstance(instance, cls).
- __subclasscheck__(subclass)
Override for issubclass(subclass, cls).
- mro()
Return a type’s method resolution order.
- register(subclass)
Register a virtual subclass of an ABC.
Returns the subclass, to allow usage as a class decorator.
- class qcodes.instrument.base.InstrumentProtocol(*args, **kwargs)[source]
Bases:
Protocol
Protocol that is useful for defining mixin classes for Instrument class
- log: InstrumentLoggerAdapter = ()
- qcodes.instrument.base.find_or_create_instrument(instrument_class: Type[qcodes.instrument.base.T], name: str, *args: Any, recreate: bool = False, **kwargs: Any) qcodes.instrument.base.T [source]
Find an instrument with the given name of a given class, or create one if it is not found. In case the instrument was found, and recreate is True, the instrument will be re-instantiated.
Note that the class of the existing instrument has to be equal to the instrument class of interest. For example, if an instrument with the same name but of a different class exists, the function will raise an exception.
This function is very convenient because it allows not to bother about which instruments are already instantiated and which are not.
If an instrument is found, a connection message is printed, as if the instrument has just been instantiated.
- Parameters
instrument_class – Class of the instrument to find or create.
name – Name of the instrument to find or create.
recreate – When
True
, the instruments gets recreated if it is found.
- Returns
The found or created instrument.