Electronic Load

Interface

Bases: Instrument

Electronic-load instrument. Methods return Measurement/Command for publishing.

Parameters:

• name

  (str) –

  Channel-name prefix for published data.

• driver

  (ELoadDriverBase) –

  Concrete E-Load driver; owns its own transport::

  eload = InstroELoad( "main", driver=BK85XXB("ASRL19::INSTR"), )

• publishers

  (list[Publisher] | None, default: None ) –

  Publishers that receive emitted Measurement/Command data.

• **kwargs

  –

  Default tags applied to every emitted Measurement/Command. Pass dataset_rid="<rid>" to auto-create a NominalCorePublisher (uses the on-disk 'default' Nominal credential).

name instance-attribute

name = name

legacy_naming instance-attribute

legacy_naming = legacy_naming

publishers instance-attribute

publishers = publishers or []

default_tags instance-attribute

default_tags: dict[str, str] = {}

background_interval property writable

background_interval

Seconds between background daemon iterations (0 = no wait).

background_enable property writable

background_enable

Whether the background daemon is enabled (must still be start()-ed).

add_publisher

add_publisher(publisher: Publisher)

Register a publisher to receive this instrument's Measurement/Command data.

publish

publish(data: Measurement | Command, **kwargs)

Fan data out to every configured publisher; kwargs pass through.

add_background_daemon_function

add_background_daemon_function(method: Callable, *args, **kwargs)

Append method to the daemon's call list. Use define_background_daemon to replace instead.

start

start()

Start the background daemon thread. No-op if already running.

stop

stop()

Signal the background daemon to stop and join it. No-op if not running.

get_channel

get_channel(
    channel_name: str,
    length: int = 1,
    wait_for_latest: bool = False,
    timeout: float = 10.0,
) -> Measurement

Return the most recent length samples for channel_name from the in-memory buffer.

Parameters:

• channel_name

  (str) –

  Name of the channel to retrieve.

• length

  (int, default: 1 ) –

  Number of trailing samples to return.

• wait_for_latest

  (bool, default: False ) –

  Block until at least length new values arrive.

• timeout

  (float, default: 10.0 ) –

  Seconds to wait when wait_for_latest=True.

Raises:

• RuntimeError –

  No background buffer; start() was not called.

• ChannelNotFoundTimeoutError –

  wait_for_latest=True and channel did not appear within timeout.

• ChannelValueTimeoutError –

  wait_for_latest=True and values did not arrive within timeout.

define_background_daemon

define_background_daemon(method: Callable, *args, **kwargs)

Replace all daemon functions with a single method (called with the given args).

open

open()

Open the underlying driver.

close

close()

Close the underlying driver and stop the daemon.

set_mode

set_mode(mode: LoadMode, channel: int = 1, **kwargs) -> Command

Set the channel's operation mode: CC, CR, CP, or CV. Not all models support every mode.

set_level

set_level(
    value: float,
    channel: int = 1,
    curr_limit: float | None = None,
    **kwargs,
) -> Command

Set the operating level in the active mode's units (CC: A, CV: V, CP: W, CR: Ω).

curr_limit applies only in CV mode. Raises ValueError if no mode has been set.

short_output

short_output(enable: bool, channel: int = 1, **kwargs) -> Command

Enable or disable the channel short.

Warning

Takes effect IMMEDIATELY. enable=True shorts the channel output.

set_range

set_range(value: float, channel: int = 1, **kwargs) -> Command

Set the range from the expected maximum operating value in the active mode's units (CC: A, CV: V, CP: W, CR: Ω).

Raises ValueError if no mode has been set.

set_slewrate

set_slewrate(
    direction: SlewRateDirection,
    rate: float,
    channel: int = 1,
    **kwargs,
) -> Command

Set the per-edge current slew rate (A/μs) for direction (RISE/FALL/BOTH).

output_enable

output_enable(enable: bool, channel: int = 1, **kwargs) -> Command

Enable or disable the output on channel.

get_current

get_current(channel: int = 1, **kwargs) -> Measurement | None

Measure the current (amperes) sensed on channel. Returns None if unavailable.

get_voltage

get_voltage(channel: int = 1, **kwargs) -> Measurement | None

Measure the voltage (volts) sensed on channel. Returns None if unavailable.

Types & Configuration

E-Load shared types: LoadMode and SlewRateDirection.

LoadMode

Bases: Enum

CC class-attribute instance-attribute

CC = 'CC'

CR class-attribute instance-attribute

CR = 'CR'

CP class-attribute instance-attribute

CP = 'CP'

CV class-attribute instance-attribute

CV = 'CV'

SlewRateDirection

Bases: Enum

RISE class-attribute instance-attribute

RISE = 'RISE'

FALL class-attribute instance-attribute

FALL = 'FALL'

BOTH class-attribute instance-attribute

BOTH = 'BOTH'

Driver Interface

Bases: ABC

Vendor E-Load driver contract. Concrete drivers own their transport and lifecycle.

open abstractmethod

open() -> None

Open the underlying transport and put the load in remote mode.

close abstractmethod

close() -> None

Close the underlying transport. Idempotent.

short_output abstractmethod

short_output(enable: bool, channel: int) -> None

Apply or release the load's short on channel. Takes effect immediately.

set_mode abstractmethod

set_mode(mode: LoadMode, channel: int) -> None

Set the operating mode on channel: CC, CV, CP, or CR.

Not every model supports every mode; drivers should raise NotImplementedError for unsupported combinations.

set_level abstractmethod

set_level(
    mode: LoadMode, value: float, channel: int, curr_limit: float | None
) -> None

Set the operating level on channel in the units appropriate for mode.

Parameters:

• mode

  (LoadMode) –

  Active load mode — caller passes it explicitly so the driver doesn't need to track state. Units: CC → amperes, CV → volts, CP → watts, CR → ohms.

• value

  (float) –

  Operating level in mode's units.

• channel

  (int) –

  Target channel (1-indexed).

• curr_limit

  (float | None) –

  Optional current limit; only meaningful in CV mode. Drivers may ignore it in other modes.

set_range abstractmethod

set_range(mode: LoadMode, value: float, channel: int) -> None

Set the operating range on channel from the expected maximum.

value is the maximum operating value in mode's units (see :meth:set_level). Drivers typically snap to the closest hardware range that covers value.

set_slewrate abstractmethod

set_slewrate(
    direction: SlewRateDirection, rate: float, channel: int
) -> None

Set the per-edge current slew rate on channel.

Parameters:

• direction

  (SlewRateDirection) –

  RISE, FALL, or BOTH — which edge(s) the rate applies to.

• rate

  (float) –

  Slew rate in amperes per microsecond (A/μs).

• channel

  (int) –

  Target channel (1-indexed).

output_enable abstractmethod

output_enable(enable: bool, channel: int) -> None

Enable or disable load draw on channel.

get_current abstractmethod

get_current(channel: int) -> float

Measure the current the load is sinking on channel (amperes).

get_voltage abstractmethod

get_voltage(channel: int) -> float

Measure the voltage at channel's terminals (volts).

Vendor Drivers

BK 85XXB

B&K Precision 8500B-series E-Load driver. Covers 8500B/8502B/8510B/8514B/8542B (shared SCPI surface).

Hardware-validated against the 8514B; other family members are expected to work but have not been bench-tested.

BK85XXB

BK85XXB(visa_resource: str | VisaConfig)

Bases: ELoadDriverBase

B&K Precision 8500B-series E-Load (8500B/8502B/8510B/8514B/8542B).

Hardware-validated against the 8514B; others share the SCPI surface but have not been bench-tested.

open

open() -> None

close

close() -> None

short_output

short_output(enable: bool, channel: int) -> None

set_mode

set_mode(mode: LoadMode, channel: int) -> None

set_level

set_level(
    mode: LoadMode, value: float, channel: int, curr_limit: float | None
) -> None

set_range

set_range(mode: LoadMode, value: float, channel: int) -> None

set_slewrate

set_slewrate(
    direction: SlewRateDirection, rate: float, channel: int
) -> None

output_enable

output_enable(enable: bool, channel: int) -> None

get_current

get_current(channel: int) -> float

get_voltage

get_voltage(channel: int) -> float

loadmode_to_unit

loadmode_to_unit(mode: LoadMode) -> str