Electronic Load¤

Interface¤

electronic load instrument interface.

Defines InstroELoad.

Public API

InstroELoad

logger `module-attribute` ¤

logger = getLogger(__name__)

InstroELoad ¤

InstroELoad(
    name: str,
    driver: ELoadDriverBase,
    publishers: list[Publisher] | None = None,
    **kwargs,
)

Bases: Instrument

E-Load hardware abstraction to communicate with various models and vendor E-Loads.

Methods return Measurement and Command data types to be compatible with Nominal Instrumentation tools.

Parameters:

name ¤
(str) –

A name to identify this e-load instance. Used in channel naming and published data.
driver ¤
(ELoadDriverBase) –
Driver instance for the specific e-load vendor/model. Concrete drivers own their transport setup::
```
eload = InstroELoad(
    "main",
    driver=BK85XXB("ASRL19::INSTR"),
)
```
publishers ¤
(list[Publisher] | None, default: None ) –

List of publishers to send data to when executing methods. Defaults to None.
**kwargs ¤
–

Optional keyword arguments used as tags throughout the life of the instrument. These tags are applied to the Measurement and Command objects and can be utilized by publishers like NominalCorePublisher as added metadata.

Special keyword arguments: dataset_rid (str): If provided, automatically creates and adds a NominalCorePublisher with the specified dataset RID. Assumes a Nominal 'default' credential is stored on disk.

name `instance-attribute` ¤

name = name

data_handler `instance-attribute` ¤

data_handler = (
    None
    if connection_config is None
    else DataHandler(select(connection_config))
)

publishers `instance-attribute` ¤

publishers = publishers or []

default_tags `instance-attribute` ¤

default_tags: dict[str, str] = {}

background_interval `property` `writable` ¤

background_interval

Get the background worker interval setting.

Returns:

float –

The current interval in seconds between background worker iterations. The worker waits this duration between executing background daemon functions.

background_enable `property` `writable` ¤

background_enable

Get the background worker enable state.

Returns:

bool –

True if the background worker is enabled, False otherwise.

open ¤

open()

Establish connection to the device.

close ¤

close()

Disconnect from the device.

set_mode ¤

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

Set the operation mode for the selected channel.

Select from the following operation modes: CC (Constant Current), CR (Constant Resistance), CP (Constant Power), or CV (Constant Voltage). Note that not all modes are supported by all e-load models. Check your model's documentation.

Parameters:

mode ¤
(LoadMode) –

The operation mode to set (CC, CR, CP, or CV).
channel ¤
(int, default: 1 ) –

The target channel. Defaults to 1.
**kwargs ¤
–

Optional keyword arguments used as tags. These tags are applied to the Command object and can be utilized by publishers like NominalCorePublisher as added metadata.

Returns:

Command ( Command ) –

A Command object containing the channel name, mode value, timestamp, and tags. The command is automatically published to all configured publishers.

Raises:

ValueError –

If an unsupported mode is specified for this e-load model.

set_level ¤

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

Set the operation level of the selected channel.

The units depend on the current operation mode: - CC (Constant Current): amperes (A) - CV (Constant Voltage): volts (V) - CP (Constant Power): watts (W) - CR (Constant Resistance): ohms (Ω)

Parameters:

value ¤
(float) –

The operating level value in the units appropriate for the current mode.
channel ¤
(int, default: 1 ) –

The specified output channel. Defaults to 1.
curr_limit ¤
(float | None, default: None ) –

The optional current limit to set when operating mode is CV (Constant Voltage). Defaults to None.
**kwargs ¤
–

Optional keyword arguments used as tags. These tags are applied to the Command object and can be utilized by publishers like NominalCorePublisher as added metadata.

Returns:

Command ( Command ) –

A Command object containing the channel name, level value, timestamp, and tags. The command is automatically published to all configured publishers.

Raises:

ValueError –

If mode has not been set before calling this method.

short_output ¤

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

Enable or disable the e-load channel short.

Warning

This action occurs IMMEDIATELY when called and will short the channel output if enabled. Use with caution.

Parameters:

enable ¤
(bool) –

True to enable the channel short, False to disable.
channel ¤
(int, default: 1 ) –

The specified output channel. Defaults to 1.
**kwargs ¤
–

Optional keyword arguments used as tags. These tags are applied to the Command object and can be utilized by publishers like NominalCorePublisher as added metadata.

Returns:

Command ( Command ) –

A Command object containing the channel name, short enable state, timestamp, and tags. The command is automatically published to all configured publishers.

set_range ¤

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

Set the operation range setting of the e-load.

This method sets the appropriate range based on the expected maximum operation value for the current mode.

Parameters:

value ¤
(float) –

Expected maximum operation value. The units depend on the current mode: - CC: maximum current in amperes (A) - CV: maximum voltage in volts (V) - CP: maximum power in watts (W) - CR: maximum resistance in ohms (Ω)
channel ¤
(int, default: 1 ) –

The specified output channel. Defaults to 1.
**kwargs ¤
–

Optional keyword arguments used as tags. These tags are applied to the Command object and can be utilized by publishers like NominalCorePublisher as added metadata.

Returns:

Command ( Command ) –

A Command object containing the channel name, range value, timestamp, and tags. The command is automatically published to all configured publishers.

Raises:

ValueError –

If mode has not been set before calling this method.

set_slewrate ¤

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

Set the slew rate in A/μs for the assigned channel.

The slew rate controls how quickly the current can change when transitioning between levels.

Parameters:

direction ¤
(SlewRateDirection) –

The edge direction to set the slew rate (RISING or FALLING).
rate ¤
(float) –

The slew rate in amperes per microsecond (A/μs).
channel ¤
(int, default: 1 ) –

The channel to set the slew rate. Defaults to 1.
**kwargs ¤
–

Optional keyword arguments used as tags. These tags are applied to the Command object and can be utilized by publishers like NominalCorePublisher as added metadata.

Returns:

Command ( Command ) –

A Command object containing the channel name, slew rate value, timestamp, and tags. The command is automatically published to all configured publishers.

output_enable ¤

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

Enable or disable the channel output.

Parameters:

enable ¤
(bool) –

True to enable the output, False to disable.
channel ¤
(int, default: 1 ) –

The specified output channel. Defaults to 1.
**kwargs ¤
–

Optional keyword arguments used as tags. These tags are applied to the Command object and can be utilized by publishers like NominalCorePublisher as added metadata.

Returns:

Command ( Command ) –

A Command object containing the channel name, enable state, timestamp, and tags. The command is automatically published to all configured publishers.

get_current ¤

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

Query the current that the e-load senses through its terminals.

Parameters:

channel ¤
(int, default: 1 ) –

The specified output channel. Defaults to 1.
**kwargs ¤
–

Optional keyword arguments used as tags. These tags are applied to the Measurement object and can be utilized by publishers like NominalCorePublisher as added metadata.

Returns:

Measurement | None –

Measurement | None: A Measurement object containing the channel name, current value, timestamp, and tags. The measurement is automatically published to all configured publishers. Returns None if the measurement could not be obtained.

get_voltage ¤

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

Query the voltage that the e-load senses is active on its terminals.

Parameters:

channel ¤
(int, default: 1 ) –

The specified output channel. Defaults to 1.
**kwargs ¤
–

Optional keyword arguments used as tags. These tags are applied to the Measurement object and can be utilized by publishers like NominalCorePublisher as added metadata.

Returns:

Measurement | None –

Measurement | None: A Measurement object containing the channel name, voltage value, timestamp, and tags. The measurement is automatically published to all configured publishers. Returns None if the measurement could not be obtained.

add_publisher ¤

add_publisher(publisher: Publisher)

Add a publisher to the list of publishers for this instrument.

Publishers receive all Measurement and Command objects that are published by this instrument. Multiple publishers can be added to send data to different destinations.

Parameters:

publisher ¤
(Publisher) –

The publisher instance to add.

publish ¤

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

Publish a Measurement or Command to all configured publishers.

This method sends the data to all publishers that have been added to this instrument. Additional keyword arguments are passed through to each publisher's publish method.

Parameters:

data ¤
(Measurement | Command) –

The measurement or command data to publish.
**kwargs ¤
–

Optional keyword arguments passed to each publisher's publish method.

get_identity ¤

get_identity() -> str

Query the instrument's identity string.

This method sends the SCPI "*IDN?" command to retrieve the instrument's identification information, which typically includes manufacturer, model number, serial number, and firmware version.

Returns:

str ( str ) –

The instrument's identity string.

Raises:

RuntimeError –

If no connection is configured for this instrument (data_handler is None).

open_and_get_identity `staticmethod` ¤

open_and_get_identity(connection_config: ConnectConfig) -> str

Convenience method to open a connection, query identity, and close.

This static method creates a temporary instrument instance, opens a connection, queries the identity, closes the connection, and returns the identity string. Useful for instrument discovery without maintaining a long-lived connection.

Parameters:

connection_config ¤
(ConnectConfig) –

The connection configuration for the instrument.

Returns:

str ( str ) –

The instrument's identity string.

Raises:

RuntimeError –

If the connection cannot be established or the identity cannot be queried.

send_arbitrary_command ¤

send_arbitrary_command(command: str)

Send an arbitrary command string to the instrument.

This method allows sending custom commands directly to the instrument without going through the instrument's high-level API. Useful for accessing instrument-specific features not exposed by the standard interface.

Parameters:

command ¤
(str) –

The command string to send to the instrument.

Raises:

RuntimeError –

If no connection is configured for this instrument (data_handler is None).

query_arbitrary_command ¤

query_arbitrary_command(command: str) -> str

Send an arbitrary command string and return the instrument's response.

This method sends a command and waits for a response, useful for querying instrument state or configuration. The response is returned as a string.

Parameters:

command ¤
(str) –

The query command string to send to the instrument.

Returns:

str ( str ) –

The instrument's response to the query command.

Raises:

RuntimeError –

If no connection is configured for this instrument (data_handler is None).

add_background_daemon_function ¤

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

Adds a function (and its arguments) to be periodically called by the background worker daemon.

There may already be functions defined and this will add to the end of that list. Call define_background_daemon to clear and define a new function if you do not want the default functions to run.

Parameters:

method ¤
(Callable) –

The method/function to be invoked in the background thread.
*args ¤
–

Positional arguments to pass to the method.
**kwargs ¤
–

Keyword arguments to pass to the method.

start ¤

start()

Start the background worker thread.

This method creates and starts a daemon thread that periodically executes all registered background daemon functions. If the thread is already running, this method does nothing. The thread will continue running until stop() is called.

stop ¤

stop()

Stop the background worker thread.

This method signals the background worker thread to stop and waits for it to complete. If the thread is not running, this method does nothing.

get_channel ¤

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

Get most recent Measurement data for a specific channel from the buffer.

Parameters:

channel_name ¤
(str) –

The name of the channel from which to retrieve data.
length ¤
(int, default: 1 ) –

The number of most recent samples to return.
wait_for_latest ¤
(bool, default: False ) –

Block and wait for the next channel value(s).
timeout ¤
(float, default: 10.0 ) –

Timeout in seconds when waiting for channel or values. Defaults to 10.0 seconds. Only applies when wait_for_latest=True.

Returns:

Measurement ( Measurement ) –

A Measurement object containing the requested channel data and timestamps.

Raises:

RuntimeError –

No background buffer exists because start() was not called.
ChannelNotFoundTimeoutError –

If wait_for_latest=True and the channel does not appear within timeout.
ChannelValueTimeoutError –

If wait_for_latest=True and sufficient values are not available within timeout.

define_background_daemon ¤

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

Clear all background daemon functions and register a single custom method.

This method clears any previously registered background daemon functions and registers a new method to be called in the background daemon loop. This is useful when you want to replace the default background functions with a custom implementation.

Parameters:

method ¤
(Callable) –

The method to call as part of the background daemon.
*args ¤
–

Positional arguments to pass to the method when it is called.
**kwargs ¤
–

Keyword arguments to pass to the method when it is called.

Types & Configuration¤

electronic load instrument interface and helpers.

Defines LoadMode and related helpers. Public API: LoadMode, 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¤

electronic load driver base interface.

Defines ELoadDriverBase.

Public API

ELoadDriverBase

ELoadDriverBase ¤

Bases: ABC

Abstract base class for vendor E-Load drivers.

Concrete drivers own their transport setup and translate category-level calls into vendor-specific commands. The base declares only the category contract; transport choice and lifecycle live in the concrete driver.

open `abstractmethod` ¤

open() -> None

Open the driver's underlying transport.

close `abstractmethod` ¤

close() -> None

Close the driver's underlying transport.

short_output `abstractmethod` ¤

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

set_mode `abstractmethod` ¤

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

set_level `abstractmethod` ¤

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

set_range `abstractmethod` ¤

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

set_slewrate `abstractmethod` ¤

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

output_enable `abstractmethod` ¤

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

get_current `abstractmethod` ¤

get_current(channel: int) -> float

get_voltage `abstractmethod` ¤

get_voltage(channel: int) -> float

Vendor Drivers¤

BK 85XXB¤

B&K Precision 8500B-series driver for electronic loads.

Implements BK85XXB, which owns the SCPI/VISA transport for the B&K Precision 8500B family of electronic loads (8500B, 8502B, 8510B, 8514B, 8542B). All models in this family share the SCPI surface documented in the 8500B Series Programming Manual. Hardware-validated against the 8514B; other family members are expected to work but have not been bench-tested.

Public API

loadmode_to_unit, BK85XXB

BK85XXB ¤

BK85XXB(
    connection: str | VisaConnectionConfig,
    *,
    visa_backend: str = "@ivi",
    serial_config: SerialConfig | None = None,
    terminator: TerminatorConfig | None = None,
    timeout: TimeoutConfig | None = None,
)

Bases: ELoadDriverBase

Driver for the B&K Precision 8500B-series electronic loads.

Covers the 8500B, 8502B, 8510B, 8514B, and 8542B — all share the SCPI surface defined in the 8500B Series Programming Manual. Hardware-validated against the 8514B; other family members should work but have not been bench-tested.

The driver owns the SCPI/VISA transport. Users provide connection parameters for the instrument, and the driver handles VisaDriver construction internally.

Parameters:

connection ¤
(str | VisaConnectionConfig) –

VISA resource string, or a full VisaConnectionConfig when the caller needs to pass a prebuilt config object.
visa_backend ¤
(str, default: '@ivi' ) –

pyvisa backend specifier. Ignored when connection is already a VisaConnectionConfig.
serial_config ¤
(SerialConfig | None, default: None ) –

Optional serial-line settings for ASRL resources.
terminator ¤
(TerminatorConfig | None, default: None ) –

Optional read/write terminator settings.
timeout ¤
(TimeoutConfig | None, default: None ) –

Optional operation timeout settings.

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

Electronic Load¤

Interface¤

logger module-attribute ¤

InstroELoad ¤

name ¤

driver ¤

publishers ¤

**kwargs ¤

name instance-attribute ¤

data_handler instance-attribute ¤

publishers instance-attribute ¤

default_tags instance-attribute ¤

background_interval property writable ¤

background_enable property writable ¤

open ¤

close ¤

set_mode ¤

mode ¤

channel ¤

**kwargs ¤

set_level ¤

value ¤

channel ¤

curr_limit ¤

**kwargs ¤

short_output ¤

enable ¤

channel ¤

**kwargs ¤

set_range ¤

value ¤

channel ¤

**kwargs ¤

set_slewrate ¤

direction ¤

rate ¤

channel ¤

**kwargs ¤

output_enable ¤

enable ¤

channel ¤

**kwargs ¤

get_current ¤

channel ¤

**kwargs ¤

get_voltage ¤

channel ¤

**kwargs ¤

add_publisher ¤

publisher ¤

publish ¤

data ¤

**kwargs ¤

get_identity ¤

open_and_get_identity staticmethod ¤

connection_config ¤

send_arbitrary_command ¤

command ¤

query_arbitrary_command ¤

command ¤

add_background_daemon_function ¤

method ¤

*args ¤

**kwargs ¤

start ¤

stop ¤

get_channel ¤

channel_name ¤

length ¤

wait_for_latest ¤

timeout ¤

define_background_daemon ¤

method ¤

*args ¤

**kwargs ¤

Types & Configuration¤

LoadMode ¤

CC class-attribute instance-attribute ¤

CR class-attribute instance-attribute ¤

CP class-attribute instance-attribute ¤

logger `module-attribute` ¤

`name` ¤

`driver` ¤

`publishers` ¤

`kwargs`** ¤

name `instance-attribute` ¤

data_handler `instance-attribute` ¤

publishers `instance-attribute` ¤

default_tags `instance-attribute` ¤

background_interval `property` `writable` ¤

background_enable `property` `writable` ¤

`mode` ¤

`channel` ¤

`kwargs`** ¤

`value` ¤

`channel` ¤

`curr_limit` ¤

`kwargs`** ¤

`enable` ¤

`channel` ¤

`kwargs`** ¤

`value` ¤

`channel` ¤

`kwargs`** ¤

`direction` ¤

`rate` ¤

`channel` ¤

`kwargs`** ¤

`enable` ¤

`channel` ¤

`kwargs`** ¤

`channel` ¤

`kwargs`** ¤

`channel` ¤

`kwargs`** ¤

`publisher` ¤

`data` ¤

`kwargs`** ¤

open_and_get_identity `staticmethod` ¤

`connection_config` ¤

`command` ¤

`command` ¤

`method` ¤

**`*args`** ¤

`kwargs`** ¤

`channel_name` ¤

`length` ¤

`wait_for_latest` ¤

`timeout` ¤

`method` ¤

**`*args`** ¤

`kwargs`** ¤

CC `class-attribute` `instance-attribute` ¤

CR `class-attribute` `instance-attribute` ¤

CP `class-attribute` `instance-attribute` ¤

CV `class-attribute` `instance-attribute` ¤

RISE `class-attribute` `instance-attribute` ¤

FALL `class-attribute` `instance-attribute` ¤

BOTH `class-attribute` `instance-attribute` ¤

open `abstractmethod` ¤

close `abstractmethod` ¤

short_output `abstractmethod` ¤

set_mode `abstractmethod` ¤

set_level `abstractmethod` ¤

set_range `abstractmethod` ¤

set_slewrate `abstractmethod` ¤

output_enable `abstractmethod` ¤

get_current `abstractmethod` ¤

get_voltage `abstractmethod` ¤

`connection` ¤

`visa_backend` ¤

`serial_config` ¤

`terminator` ¤

`timeout` ¤