QCoDeS [UNRELEASED DRAFT] (2026-08-07)

Breaking Changes:

• Legacy backwards-compatibility aliases across the instrument_drivers module that were deprecated in QCoDeS 0.57.0 have been removed. This includes deprecated class aliases and deprecated module shims for AlazarTech, Basel, Galil, HP, Ithaco, Keithley, Keysight, Mini-Circuits, Oxford Instruments, Rigol, Rohde & Schwarz, Signal Hound, Stanford Research Systems, Tektronix, Weinschel, and Yokogawa drivers. Users should migrate to the canonical class names listed in the 0.57.0 changelog. (#8060)

• Several module-level TypeVar definitions and type aliases that are no longer used internally have been deprecated. Importing them will emit a QCoDeSDeprecationWarning. They will be removed in a future version. (#8096)

• Removed deprecated VISA-related APIs from VisaInstrument: the _address property (use address instead) and the visalib property (use visabackend instead). The unused and deprecated MockAMI430 mocker class has also been removed. (#8103)

• Importing the short hand aliases (such as Parameter, Measurement, Instrument, Monitor and Station) from the top level qcodes namespace is now deprecated and emits a QCoDeSDeprecationWarning. Import these names from their respective submodules (for example qcodes.parameters, qcodes.dataset or qcodes.station) instead. The submodules themselves (such as qcodes.dataset and qcodes.instrument) remain accessible from the top level qcodes namespace and are not deprecated.

  Similarly, importing the parameter classes (such as Parameter, ManualParameter and DelegateParameter) from qcodes.instrument is now deprecated and emits a QCoDeSDeprecationWarning. Import these names from qcodes.parameters instead. The names remain available from qcodes.instrument at runtime for backwards compatibility but are hidden from static type checkers, so importing them from qcodes.instrument is reported as an unknown attribute. (#8252)

• The default format of DataSetProtocol.run_timestamp, DataSetProtocol.completed_timestamp and qcodes.dataset.sqlite.queries.raw_time_to_str_time changed from "%Y-%m-%d %H:%M:%S" to "%Y-%m-%d %H:%M:%S%z", i.e. the rendered timestamps now include the UTC offset of the local timezone, e.g. "2026-07-31 10:27:25+0200".

  Timestamps are stored in the QCoDeS database as POSIX timestamps, which do not capture the timezone in which the measurement was performed. They are therefore still rendered in the local timezone of the machine reading the dataset, but the resulting string is no longer ambiguous. This also applies to the run_timestamp and completed_timestamp attributes written when exporting a dataset to NetCDF or xarray.

  Pass an explicit fmt argument to restore the previous behaviour.

  Parameter cache timestamps are now timezone aware. ParameterBase.cache.timestamp (and therefore Parameter.get_latest.get_timestamp()) returns a datetime with tzinfo set to the local timezone rather than a naive datetime. Code that compares these timestamps to naive datetime objects will raise TypeError and must be updated to use timezone aware datetimes.

  Consequently the "ts" field of a parameter snapshot changed from "%Y-%m-%d %H:%M:%S" to ISO 8601 format including the UTC offset, e.g. "2026-07-31 10:27:25+02:00". Snapshots can be parsed with datetime.datetime.fromisoformat. (#8345)

• The default value of the update argument of snapshot, snapshot_base and print_readable_snapshot (on every Metadatable, including instruments, channels and parameters) is now "Only_invalid". Previously calling e.g. instrument.snapshot() or parameter.snapshot() without an argument effectively defaulted to the equivalent of "Never" and never refreshed anything. As a result, snapshot() (and print_readable_snapshot()) will now call get() on parameters whose cache is invalid, which may query the underlying instrument. Pass update="Never" explicitly to restore the previous “do not update” behavior, or update="All" to force a full update.

  Relatedly, the station snapshot that Measurement stores before a measurement starts is now taken with update="Only_invalid" (previously the equivalent of "Never"), so parameters with an invalid cache are refreshed via a single get while parameters with a valid cache keep their cached value.

  The legacy True / None / False values of the update argument are now deprecated aliases for "All" / "Only_invalid" / "Never". They keep working (no runtime warning is raised), but type checkers will flag their use; prefer the string values instead. (#8354)

Improved:

• Instrument.close_all() gained an only_subclasses keyword argument. When set to True, only instruments that are instances of the class (or its subclasses) on which close_all is called are closed, leaving other registered instruments open. The log_status and only_subclasses arguments are now keyword-only. (#8312)

Improved Drivers:

• Fixed three bugs in qcodes.instrument_drivers.QuantumDesign.DynaCoolPPMS.DynaCool.DynaCool that prevented the driver from instantiating and from updating the temperature_setpoint cache:

  • block_while_ramping_temperature is now created with set_cmd=None / get_cmd=None so it behaves as a settable cache-only parameter, instead of set_cmd=False / get_cmd=False which made it read-only and rejected the supplied initial_value.

  • Removed the duplicate instrument=self argument from the blocking_t_state_check_interval parameter creation, which is supplied automatically by add_parameter and was raising on construction.

  • Fixed an AttributeError when setting the temperature: the cache update in _set_temperature_and_state now correctly references self.temperature_setpoint rather than the non-existent self.setpoint. (#8097)

• Correct the lower bound of the span parameter validator of the KeysightPNABase driver to 0 Hz. (#8195)

• Referring to the:

  • Keysight Trueform Series Operating and Service Guide

  • Agilent 33210A 10 MHz Function / Arbitrary Waveform Generator User’s Guide

  • Agilent 33250A 80 MHz Function / Arbitrary Waveform Generator

  Improvements:

  • Expanded the list of supported devices for the KeysightAgilent_33XXX driver

  • Added implementations of SCPI commands for working with: ARB signals, edges of Pulse function, output termination, voltage autoranging

  • Created tests for new commands and update sim file

• Fixed the timezone offset written into the waveform and sequence files generated by the Tektronix AWG70000A drivers. The offset was computed manually from time.timezone, which gave the offset the wrong sign and ignored daylight saving time, so e.g. a machine in UTC+02:00 wrote -02:00. The offset is now taken from the local timezone of the timestamp itself. (#8345)

• The QDev QDac driver now honors the "Only_invalid" snapshot update mode: when snapshotting, the bulk status read that refreshes the channel v/i/irange/vrange caches is only performed for update="All", or for update="Only_invalid" when one of those channel caches is actually invalid. Previously the bulk read was performed on every snapshot that was not "Never", which made repeated snapshots unnecessarily expensive even when the channel caches were already valid. (#8354)

New:

• Added qcodes.dataset.get_db_overview(), a fast way to list the runs in a QCoDeS database. It fetches run metadata (experiment/sample names, timestamps, record counts and guids) via a single JOIN query on the runs and experiments tables, without instantiating a DataSet object per run, making it possible to list databases with many thousands of runs almost instantly. The returned qcodes.dataset.RunOverviewDict is also exported on the public qcodes.dataset namespace. The function does not return snapshots as they can be large and slow down building the database overview. The number of results in each dataset is taken from shape information when available, and otherwise falls back to a best-effort count of the rows in the so-called results table that exists for every dataset, which may NOT be as precise as DataSet.number_of_results. (#8266)

• The update argument of snapshot and snapshot_base (available on every Metadatable, including instruments, channels and parameters) now accepts the explicit string values "All", "Only_invalid" and "Never":

  • "All" forces an update of every value (calls get() on each parameter).

  • "Only_invalid" only refreshes parameters whose cache is invalid, via a single get (cache.get(get_if_invalid=True)), and uses the cached value for everything else.

  • "Never" never updates and uses the latest values already in memory.

  The new public helper qcodes.metadatable.normalize_snapshot_update() and the qcodes.metadatable.SnapshotUpdate type are exported for drivers that override snapshot_base and need to interpret the update argument. (#8354)

Under the hood:

• Importing the top level qcodes namespace no longer eagerly imports the dataset, instrument, parameters, monitor, station and validators submodules. The discouraged short hand aliases (such as qcodes.Parameter and qcodes.Measurement) as well as qcodes.validators are still available at runtime via a lazy module level __getattr__, but they are intentionally hidden from static type checkers and are now reported as unknown attributes rather than typed as Any; import the names from their respective submodules to retain type information. This breaks a large import cycle spanning the parameters, dataset and instrument packages that triggered an internal error in mypy 2.2. (#8252)