MeasurementLink Support for Python v1.3.0-dev0 🎃👻

What's Changed

• Simplified session management (#386 #389 #402 #426 #429 #432 #433 #436 #438 #440 #442 #446 #466 #469 #480 #481 #482)
  • The MeasurementContext class now provides reserve_session(s) methods, eliminating the need to explicitly instantiate a SessionManagementClient and pass measurement_service.context.pin_map_context to it. Example:

    with measurement_service.context.reserve_sessions(pin_names) as reservation:
        ...

  • The reserve_session(s) methods now accept a single pin name in addition to a list of pin names.
  • The reservation classes now provide initialize_${driver}_session(s) methods for initializing modular instrument sessions. These methods are designed to be used in a with block. They yield one or multiple SessionInformation objects, which now contain a reference to the session object.
    Example:

    with reservation.initialize_nidcpower_sessions() as session_infos:
        for session_info in session_infos:
            session_info.session.channels[session_info.channel_list].initiate()

  • The reservation classes now provide get_${driver}_connection(s) methods for querying connections between pins and instrument channels. These methods return one or multiple Connection objects, which also contain a reference to the instrument session object.
    Example:

    vdd_connection = reservation.get_nidcpower_connection("Vdd")
    measurement = vdd_connection.session.channels[vdd_connection.channel_name].measure_multiple()

  • The reservation classes also provide:
    • create_nidaqmx_task(s) and get_nidaqmx_connection(s) methods for NI-DAQmx.
    • Generic initialize_session(s) and get_connection(s) methods for custom session types, such as instrument drivers based on VISA.
  • The new reservation methods have type hints, which enable LSP-enabled text editors such as VS Code and PyCharm to auto-complete references to driver-specific session objects. For example, reservation.get_nidmm_connection(pin).session. should auto-complete by displaying the methods for the nidmm.Session class. To support these type hints, the new methods use generic protocol classes TypedSessionInformation[TSession] and TypedConnection[TSession].
  • The reservation.session_info property now includes the session object(s) in the returned SessionInformation objects, if they have been created. However, clients are encouraged to use the type-safe TypedSessionInformation[TSession] objects returned from reservation.initialize_${driver}_session(s).
  • TestStand code modules can also use the new initialize_${driver}_sessions methods. These methods accept an optional initialization_behavior enum parameter, which has INITIALIZE_SESSION_THEN_DETACH and ATTACH_TO_SESSION_THEN_CLOSE enum values designed for this use case.
  • The example measurements and TestStand code modules have been updated to use the new session management API. As such, most of the examples now require ni-measurementlink-service version 1.3.0-dev0 or later. For example measurements that work with previous versions, use the examples zip file provided with that release on GitHub.
• Configuration via .env files (#421 #425 #441)
  • You can now configure ni-measurementlink-service settings by setting environment variables or creating a .env file.
    • A .env file is a text file containing environment variables in the form VAR=value.
    • The .env may be located in the measurement service's current working directory or one of its parent directories. For example, you can place a .env file at the root of this GitHub repo, in the examples/nidcpower_source_dc_voltage directory, or in C:\ProgramData\National Instruments\MeasurementLink for configuring statically registered services.
    • If the current working directory and its parents do not contain a .env file, the search falls back to the script/EXE path (if there is one) or the path of the Python module calling into ni-measurementlink-service (to support TestStand code modules).
    • Support for parsing the .env file is implemented by the 3rd party python-decouple package.
  • The modular instrument initialize_${driver}_sessions(s) methods allow you to use .env settings to override the IVI option string and specify simulation options.
    Example:

    # Add this to your .env file to enable NI-DCPower simulation with PXIe-4141 instruments.
    MEASUREMENTLINK_NIDCPOWER_SIMULATE=1
    MEASUREMENTLINK_NIDCPOWER_BOARD_TYPE=PXIe
    MEASUREMENTLINK_NIDCPOWER_MODEL=4141
    

  • The example measurements no longer have a hardcoded USE_SIMULATION constant that you must edit to enable/disable simulation. To enable simulation for all example measurements, copy .env.simulation to .env in the root of this Git repo.
  • The VISA example measurements use python-decouple directly to read MEASUREMENTLINK_VISA_DMM_SIMULATE from the .env file.
  • There are a few other .env settings for overriding the NI gRPC Device Server configuration and enabling feature toggles. For a complete reference, see .env.sample in the root of this Git repo.
• Python 3.12 support (#427)
  • ni-measurementlink-service is now tested with Python 3.12.
  • No code changes were required, so previous releases should work with Python 3.12 as well.
• Example improvements
  • The VISA examples now have a visa_dmm instrument driver rather than using VISA directly. (#439, #447)
  • The reservation timeout and instrument type ID parameters have been removed from the examples because the defaults are sufficient. (#393)
  • The example TestStand code modules have been split into teststand_pin_map.py, teststand_nidcpower.py, teststand_nidmm.py etc. to faciliate reuse and make it easier to mix and match code modules in the same sequence. (#460 #461 #465)
• Documentation improvements (#430)
  • The API reference documentation now includes more accurate type information with hyperlinks.
  • The API reference documentation now includes hyperlinks to the documentation for nimi-python, nidaqmx-python, and the Python standard library.

  Note These improvements will not be visible on https://ni.github.io/measurementlink-python/ until version 1.3 is officially released.

• Bug fixes
  • Some cosmetic issues with example measurement UI panels have been fixed. (#420 #424 #435)
  • Copying an example measurement into a separate Git repo no longer causes ni-python-styleguide to reorder its import directives. (#374 #443)
  • ServerCallLogger no longer incorrectly logs OK when the call is canceled. (#370 #462)
  • Fixed several APIs that leak internal types. (#375 #394 #396 #437)
    • The DiscoveryClient class is now publicly available via the ni_measurement_service.discovery sub-package.
    • The DiscoveryClient.register_measurement_service method has been deprecated in favor of a more general register_service API that supports other service types and registering multiple services.
    • In several public and internal classes, attributes and properties that should not be public have been deprecated and will be removed in a future release.
    • Deprecated attributes, methods, and properties generate deprecation warnings, which are enabled by default for pytest tests but not for standalone Python scripts.
  • In the examples and generator templates, start.bat now assumes you are using an in-project virtualenv. (#416 #417)
  • The DiscoveryClient class now reads the MeasurementLink installation directories from the Windows registry instead of environment variables, eliminating the need to use passenv when testing with Tox. (#483 )
• Development workflow improvements
  • We are now using Mend Renovate to update dependencies. (#444 #445 #470 #471)
  • We now have a self-hosted GitHub runner for running system tests. (#479)
• Miscellaneous minor improvements and fixes

New Contributors

• @Avinash2Suresh made their first contribution in #439
• @renovate made their first contribution in #474
• @jayaseelan-james made their first contribution in #466

Full Changelog: 1.2.0...1.3.0-dev0