# InstroPSU

## class InstroPSU( name: str | None = None, driver: PSUDriverBase | None = None, num_channels: int | None = None, publishers: list[Publisher] | None = None, config: PSUConfig | dict | Path | str | None = None, autostart: bool = False, **kwargs, )[source]

Bases: [`Instrument`](https://dev.nominal.io/instro/ref/library/instro.lib.instrument.Instrument.md#instro.lib.instrument.Instrument "instro.lib.instrument.Instrument")

Power-supply instrument. Methods return Measurement/Command for publishing.

Initialize an InstroPSU.

Provide either `config` or `driver`/`num_channels` together, not both.

Parameters:
:   - **name**

      Channel-name prefix for published data. Falls back to
      `config.device.name` when `config` is given.
    - **driver**

      Concrete PSU driver; owns its own transport:

      ```
      psu = InstroPSU(
          name="main",
          driver=BK9115("USB0::0xFFFF::0x9115::SN::INSTR"),
          num_channels=1,
      )
      ```
    - **num_channels**

      Number of output channels on this PSU.
    - **publishers**

      Publishers that receive emitted Measurement/Command data.
      Combined with any publishers declared in `config`.
    - **config**

      A `PSUConfig`, a dict, or a path to a JSON config file.
    - **autostart**

      When True, open the connection and start background polling.
    - ****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).

Attributes

| [`background_interval`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.background_interval "instro.psu.InstroPSU.background_interval") | Seconds between background daemon iterations (0 = no wait). |
| --- | --- |
| [`channel_names`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.channel_names "instro.psu.InstroPSU.channel_names") | Return an insertion-ordered snapshot of all published channel names. |

Methods

| [`add_background_daemon_function`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.add_background_daemon_function "instro.psu.InstroPSU.add_background_daemon_function") | Append `method` to the daemon's call list. |
| --- | --- |
| [`add_publisher`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.add_publisher "instro.psu.InstroPSU.add_publisher") | Register a publisher to receive this instrument's Measurement/Command data. |
| [`apply`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.apply "instro.psu.InstroPSU.apply") | Set the current limit, then the voltage, then the output state on `channel`. |
| [`clear_protection`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.clear_protection "instro.psu.InstroPSU.clear_protection") | Clear every latched protection trip on `channel`. |
| [`close`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.close "instro.psu.InstroPSU.close") | Disconnect from the device. |
| [`define_background_daemon`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.define_background_daemon "instro.psu.InstroPSU.define_background_daemon") | Replace all daemon functions with a single `method` (called with the given args). |
| [`get_channel`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_channel "instro.psu.InstroPSU.get_channel") | Return the most recent `length` samples for `channel_name` from the in-memory buffer. |
| [`get_current`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_current "instro.psu.InstroPSU.get_current") | Measure the current (amperes) flowing through `channel`. |
| [`get_current_setpoint`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_current_setpoint "instro.psu.InstroPSU.get_current_setpoint") | Query the configured current-limit setpoint (amperes) on `channel`. |
| [`get_operating_mode`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_operating_mode "instro.psu.InstroPSU.get_operating_mode") | Query whether `channel` is regulating in constant voltage, constant current, unregulated, or off (published as a string). |
| [`get_output_status`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_output_status "instro.psu.InstroPSU.get_output_status") | Query whether the output on `channel` is enabled. |
| [`get_overcurrent_protection_enabled`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_overcurrent_protection_enabled "instro.psu.InstroPSU.get_overcurrent_protection_enabled") | Query whether overcurrent protection is enabled on `channel`. |
| [`get_overcurrent_protection_level`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_overcurrent_protection_level "instro.psu.InstroPSU.get_overcurrent_protection_level") | Query the overcurrent protection threshold (amperes) on `channel`. |
| [`get_overcurrent_protection_tripped`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_overcurrent_protection_tripped "instro.psu.InstroPSU.get_overcurrent_protection_tripped") | Query whether overcurrent protection has tripped on `channel` and not been cleared. |
| [`get_overvoltage_protection_delay`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_overvoltage_protection_delay "instro.psu.InstroPSU.get_overvoltage_protection_delay") | Query the overvoltage protection trip delay (seconds) on `channel`. |
| [`get_overvoltage_protection_enabled`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_overvoltage_protection_enabled "instro.psu.InstroPSU.get_overvoltage_protection_enabled") | Query whether overvoltage protection is enabled on `channel`. |
| [`get_overvoltage_protection_level`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_overvoltage_protection_level "instro.psu.InstroPSU.get_overvoltage_protection_level") | Query the overvoltage protection threshold (volts) on `channel`. |
| [`get_overvoltage_protection_tripped`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_overvoltage_protection_tripped "instro.psu.InstroPSU.get_overvoltage_protection_tripped") | Query whether overvoltage protection has tripped on `channel` and not been cleared. |
| [`get_remote_sense_enabled`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_remote_sense_enabled "instro.psu.InstroPSU.get_remote_sense_enabled") | Query whether remote sense is enabled on `channel`. |
| [`get_single_channel_value`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_single_channel_value "instro.psu.InstroPSU.get_single_channel_value") | Return the most recent sample for `channel_name` from the in-memory buffer. |
| [`get_voltage`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_voltage "instro.psu.InstroPSU.get_voltage") | Measure the voltage (volts) sensed at `channel` terminals. |
| [`get_voltage_setpoint`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.get_voltage_setpoint "instro.psu.InstroPSU.get_voltage_setpoint") | Query the configured voltage setpoint (volts) on `channel`. |
| [`open`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.open "instro.psu.InstroPSU.open") | Establish connection to the device. |
| [`output_enable`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.output_enable "instro.psu.InstroPSU.output_enable") | Enable or disable the output on `channel`. |
| [`publish`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.publish "instro.psu.InstroPSU.publish") | Fan `data` out to every configured publisher; `kwargs` pass through. |
| [`set_current_limit`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.set_current_limit "instro.psu.InstroPSU.set_current_limit") | Set the current limit (amperes) on `channel`. |
| [`set_overcurrent_protection_enabled`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.set_overcurrent_protection_enabled "instro.psu.InstroPSU.set_overcurrent_protection_enabled") | Enable or disable overcurrent protection on `channel`. |
| [`set_overcurrent_protection_level`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.set_overcurrent_protection_level "instro.psu.InstroPSU.set_overcurrent_protection_level") | Set the overcurrent protection threshold (amperes) on `channel`. |
| [`set_overvoltage_protection_delay`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.set_overvoltage_protection_delay "instro.psu.InstroPSU.set_overvoltage_protection_delay") | Set the overvoltage protection trip delay (seconds) on `channel`. |
| [`set_overvoltage_protection_enabled`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.set_overvoltage_protection_enabled "instro.psu.InstroPSU.set_overvoltage_protection_enabled") | Enable or disable overvoltage protection on `channel`. |
| [`set_overvoltage_protection_level`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.set_overvoltage_protection_level "instro.psu.InstroPSU.set_overvoltage_protection_level") | Set the overvoltage protection threshold (volts) on `channel`. |
| [`set_remote_sense_enabled`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.set_remote_sense_enabled "instro.psu.InstroPSU.set_remote_sense_enabled") | Enable or disable remote sense on `channel`. |
| [`set_voltage`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.set_voltage "instro.psu.InstroPSU.set_voltage") | Set the output voltage (volts) on `channel`. |
| [`start`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.start "instro.psu.InstroPSU.start") | Start the background daemon thread. |
| [`stop`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.stop "instro.psu.InstroPSU.stop") | Signal the background daemon to stop and join it. |

### property background_interval

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

### open()[source]

Establish connection to the device.

### close()[source]

Disconnect from the device.

### apply( *, current_limit: float, voltage: float, enable: bool = False, channel: int, **kwargs, ) → list[Command][source]

Set the current limit, then the voltage, then the output state on `channel`.

The output stays off unless `enable=True` is passed, and on the default
path it is disabled before the new setpoints are written, so setpoints are
never applied to a live output. Every argument is keyword-only, so a value
can’t land on the wrong setpoint and the output can’t be energized without
`enable=True` spelled out at the call site.

Holds the resource lock across all steps so nothing observes a half-applied
channel, and publishes only after releasing it so publisher I/O never blocks
the background daemon or other threads waiting on the instrument.

Not atomic on the instrument: if a step raises, earlier steps have already
been committed and the channel is left in an unknown state. Commands for the
steps that did land are still published before the exception propagates.

### set_voltage( voltage: float, channel: int, **kwargs, ) → Command[source]

Set the output voltage (volts) on `channel`.

### get_voltage( channel: int, **kwargs, ) → Measurement | None[source]

Measure the voltage (volts) sensed at `channel` terminals. Output may vary from voltage setpoint outside of constant voltage mode. Returns `None` if unavailable.

### set_current_limit( current_limit: float, channel: int, **kwargs, ) → Command[source]

Set the current limit (amperes) on `channel`.

### get_current( channel: int, **kwargs, ) → Measurement | None[source]

Measure the current (amperes) flowing through `channel`. Output may vary from current-limit setpoint outside of constant current mode. Returns `None` if unavailable.

### output_enable( enable: bool, channel: int, **kwargs, ) → Command[source]

Enable or disable the output on `channel`.

### get_output_status( channel: int, **kwargs, ) → Measurement | None[source]

Query whether the output on `channel` is enabled. Returns `None` if unavailable.

### get_voltage_setpoint( channel: int, **kwargs, ) → Measurement | None[source]

Query the configured voltage setpoint (volts) on `channel`. Output may vary from actual measured voltage outside of constant voltage mode. Returns `None` if unavailable.

### get_operating_mode( channel: int, **kwargs, ) → Measurement | None[source]

Query whether `channel` is regulating in constant voltage, constant current, unregulated, or off (published as a string).

### get_current_setpoint( channel: int, **kwargs, ) → Measurement | None[source]

Query the configured current-limit setpoint (amperes) on `channel`. Output may vary from actual measured current outside of constant current mode. Returns `None` if unavailable.

### set_overvoltage_protection_level( voltage: float, channel: int, **kwargs, ) → Command[source]

Set the overvoltage protection threshold (volts) on `channel`.

### get_overvoltage_protection_level( channel: int, **kwargs, ) → Measurement | None[source]

Query the overvoltage protection threshold (volts) on `channel`. Returns `None` if unavailable.

### set_overvoltage_protection_enabled( enabled: bool, channel: int, **kwargs, ) → Command[source]

Enable or disable overvoltage protection on `channel`.

### get_overvoltage_protection_enabled( channel: int, **kwargs, ) → Measurement | None[source]

Query whether overvoltage protection is enabled on `channel`. Returns `None` if unavailable.

### set_overvoltage_protection_delay( delay: float, channel: int, **kwargs, ) → Command[source]

Set the overvoltage protection trip delay (seconds) on `channel`.

### get_overvoltage_protection_delay( channel: int, **kwargs, ) → Measurement | None[source]

Query the overvoltage protection trip delay (seconds) on `channel`. Returns `None` if unavailable.

### set_overcurrent_protection_level( current: float, channel: int, **kwargs, ) → Command[source]

Set the overcurrent protection threshold (amperes) on `channel`.

### get_overcurrent_protection_level( channel: int, **kwargs, ) → Measurement | None[source]

Query the overcurrent protection threshold (amperes) on `channel`. Returns `None` if unavailable.

### set_overcurrent_protection_enabled( enabled: bool, channel: int, **kwargs, ) → Command[source]

Enable or disable overcurrent protection on `channel`.

### get_overcurrent_protection_enabled( channel: int, **kwargs, ) → Measurement | None[source]

Query whether overcurrent protection is enabled on `channel`. Returns `None` if unavailable.

### clear_protection( channel: int, **kwargs, ) → Command[source]

Clear every latched protection trip on `channel`. Publishes `True` on the `protection.clear` command channel.

The output stays off after the clear; re-enable it with [`output_enable`](https://dev.nominal.io/instro/ref/instruments/instro.psu.InstroPSU.md#instro.psu.InstroPSU.output_enable "instro.psu.InstroPSU.output_enable") once the cause is fixed.

### get_overvoltage_protection_tripped( channel: int, **kwargs, ) → Measurement | None[source]

Query whether overvoltage protection has tripped on `channel` and not been cleared.

Raises `NotImplementedError` if the driver does not implement the query, or
`FeatureNotSupportedError` if the supply has no overvoltage protection.

### get_overcurrent_protection_tripped( channel: int, **kwargs, ) → Measurement | None[source]

Query whether overcurrent protection has tripped on `channel` and not been cleared.

Raises `NotImplementedError` if the driver does not implement the query, or
`FeatureNotSupportedError` if the supply has no overcurrent protection.

### set_remote_sense_enabled( enabled: bool, channel: int, **kwargs, ) → Command[source]

Enable or disable remote sense on `channel`.

### get_remote_sense_enabled( channel: int, **kwargs, ) → Measurement | None[source]

Query whether remote sense is enabled on `channel`. Returns `None` if unavailable.

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

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

### add_publisher( publisher: Publisher, )

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

### property channel_names: tuple[str, ...]

Return an insertion-ordered snapshot of all published channel names.

Names are complete after one full daemon iteration: {name}.loop_time publishes
every iteration, so call get_channel(“loop_time”, wait_for_new_samples=True)
then read channel_names to ensure the complete set has arrived.

Raises:
:   [**RuntimeError**](https://docs.python.org/3/builtins/exceptions.html#RuntimeError "(in Python v3.15)") – No background buffer; `start()` was not called.

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

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

### get_channel( channel_name: str, length: int = 1, wait_for_new_samples: bool = False, timeout: float = 10.0, ) → Measurement

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

If the channel does not exist yet, or no sample is available, the code will always block until `timeout` expires.

Parameters:
:   - **channel_name**

      Name of the channel to retrieve.
    - **length**

      Number of trailing samples to return.
    - **wait_for_new_samples**

      Block until at least `length` new values arrive.
    - **timeout**

      Seconds to wait when insufficient data exists or `wait_for_new_samples=True`.

Raises:
:   - [**RuntimeError**](https://docs.python.org/3/builtins/exceptions.html#RuntimeError "(in Python v3.15)") – No background buffer; `start()` was not called.
    - [**ChannelNotFoundError**](https://dev.nominal.io/instro/ref/library/instro.lib.publishers.channel_buffer.ChannelNotFoundError.md#instro.lib.publishers.channel_buffer.ChannelNotFoundError "instro.lib.publishers.channel_buffer.ChannelNotFoundError") – channel had no values and no data appeared before `timeout`.
      `wait_for_new_samples=True` and channel did not appear within `timeout`.
    - [**ChannelValueTimeoutError**](https://dev.nominal.io/instro/ref/library/instro.lib.publishers.channel_buffer.ChannelValueTimeoutError.md#instro.lib.publishers.channel_buffer.ChannelValueTimeoutError "instro.lib.publishers.channel_buffer.ChannelValueTimeoutError") – `wait_for_new_samples=True` and values did not arrive within `timeout`.

### get_single_channel_value( channel_name: str, ) → float | str | None

Return the most recent sample for `channel_name` from the in-memory buffer.

This will not wait, if data is not available then `None` is returned.

Parameters:
:   **channel_name**

    Name of the channel to retrieve.

Raises:
:   [**RuntimeError**](https://docs.python.org/3/builtins/exceptions.html#RuntimeError "(in Python v3.15)") – No background buffer; `start()` was not called.

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

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

### start()

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

### stop()

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