VirtualPSU#

class VirtualPSU( num_channels: int = DEFAULT_NUM_CHANNELS, load_resistance: float | Mapping[int, float] = DEFAULT_LOAD_RESISTANCE, )[source]#

Bases: PSUDriverBase

PSU simulated in-process: no transport, server, or hardware.

Each channel drives its own resistive load. With the output on, a channel holds its voltage setpoint (constant voltage) until the load would draw more than the current limit, then holds the current limit (constant current). Readings carry 0.5% noise, the SCPI simulator’s level. The current limit starts at the channel maximum (10 A), so setting a voltage and enabling the output is enough to see it.

As on the SCPI simulator, voltages must lie within 0 to 60 V and currents within 0 to 10 A, or the setter raises ValueError. Unlike it, a setpoint may sit above its protection level, which is how a virtual channel trips: there is no external source to push the output past its setpoint.

Enabled overvoltage or overcurrent protection trips when the output exceeds its level, latching the output off until clear_protection and a new output_enable; output_enable alone also clears the latch, as on the SCPI simulator. As there, protection is checked after every change that can move the output (setpoints, protection settings, output enable, and the load), so a fault trips when it happens, and readings never change state. Remote sense and the overvoltage protection delay are stored and have no effect on readings. To exercise the VISA transport as well, use SimulatedPSU with the bundled SCPI simulator.

Create a virtual PSU.

Parameters:

num_channels (int)

Number of output channels, numbered from 1. Pass the same count to InstroPSU; a channel above it raises ValueError.
load_resistance (float | Mapping[int, float])

Resistance of each channel’s load, in ohms: one value for every channel, or a mapping from channel to value, with channels left out at 1000 ohms. 0 is a short and math.inf an open circuit. Change it at any time with set_load_resistance to move a channel between constant voltage and constant current.

Raises:

ValueError – num_channels is less than 1, or load_resistance is negative or names a channel that does not exist.

Example:

from instro.psu import InstroPSU
from instro.psu.drivers import VirtualPSU

driver = VirtualPSU(num_channels=2, load_resistance={1: 10.0, 2: 1.0})
with InstroPSU(name="psu", driver=driver, num_channels=2) as psu:
    for channel in (1, 2):
        psu.apply(current_limit=1.0, voltage=5.0, enable=True, channel=channel)
    print(psu.get_operating_mode(channel=1).latest)  # CV: 10 ohms draws 0.5 A
    print(psu.get_operating_mode(channel=2).latest)  # CC: 1 ohm would draw 5 A
    driver.set_load_resistance(100.0, channel=2)
    print(psu.get_operating_mode(channel=2).latest)  # CV

Methods

`clear_protection`	Clear every latched protection trip on `channel`.
`close`	Nothing to disconnect.
`get_current`	Query the measured output current (amperes) on `channel`.
`get_current_setpoint`	Query the configured current-limit setpoint (amperes) on `channel`.
`get_load_resistance`	Return the load resistance on `channel`, in ohms.
`get_operating_mode`	Query whether `channel` is regulating in constant voltage, constant current, unregulated, or off.
`get_output_status`	Query whether the output on `channel` is enabled.
`get_overcurrent_protection_enabled`	Query whether overcurrent protection is enabled on `channel`.
`get_overcurrent_protection_level`	Query the overcurrent protection threshold (amperes) on `channel`.
`get_overcurrent_protection_tripped`	Query whether overcurrent protection has tripped on `channel` and not been cleared.
`get_overvoltage_protection_delay`	Query the overvoltage protection trip delay (seconds) on `channel`.
`get_overvoltage_protection_enabled`	Query whether overvoltage protection is enabled on `channel`.
`get_overvoltage_protection_level`	Query the overvoltage protection threshold (volts) on `channel`.
`get_overvoltage_protection_tripped`	Query whether overvoltage protection has tripped on `channel` and not been cleared.
`get_remote_sense_enabled`	Query whether remote sense is enabled on `channel`.
`get_voltage`	Query the measured output voltage (volts) on `channel`.
`get_voltage_setpoint`	Query the configured voltage setpoint (volts) on `channel`.
`open`	Nothing to connect to.
`output_enable`	Enable or disable the output on `channel`.
`set_current_limit`	Set the current limit (amperes) on `channel`.
`set_load_resistance`	Set the load on `channel`, or on every channel when `channel` is `None`.
`set_overcurrent_protection_enabled`	Enable or disable overcurrent protection on `channel`.
`set_overcurrent_protection_level`	Set the overcurrent protection threshold (amperes) on `channel`.
`set_overvoltage_protection_delay`	Stored; protection trips without delay.
`set_overvoltage_protection_enabled`	Enable or disable overvoltage protection on `channel`.
`set_overvoltage_protection_level`	Set the overvoltage protection threshold (volts) on `channel`.
`set_remote_sense_enabled`	Stored; the virtual load has no lead resistance, so readings are unchanged.
`set_voltage`	Set the output voltage (volts) on `channel`.

set_load_resistance( resistance: float, channel: int | None = None, ) → None[source]#

Set the load on channel, or on every channel when channel is None.

Parameters:

resistance (float)

Load resistance in ohms. 0 is a short and math.inf an open circuit.
channel (int | None)

Target channel (1-indexed), or None for every channel.

Raises:

ValueError – resistance is negative, or channel does not exist.

get_load_resistance(channel: int) → float[source]#: Return the load resistance on channel, in ohms.

open() → None[source]#: Nothing to connect to.

close() → None[source]#: Nothing to disconnect.

set_voltage(voltage: float, channel: int) → None[source]#: Set the output voltage (volts) on channel.

get_voltage(channel: int) → float[source]#: Query the measured output voltage (volts) on channel. Output may vary from voltage setpoint outside of constant voltage mode.

set_current_limit(current_limit: float, channel: int) → None[source]#: Set the current limit (amperes) on channel.

get_current(channel: int) → float[source]#: Query the measured output current (amperes) on channel. Output may vary from current-limit setpoint outside of constant current mode.

output_enable(enable: bool, channel: int) → None[source]#: Enable or disable the output on channel.

get_output_status(channel: int) → bool[source]#: Query whether the output on channel is enabled.

get_voltage_setpoint(channel: int) → float[source]#: Query the configured voltage setpoint (volts) on channel. Output may vary from actual measured voltage outside of constant voltage mode.

get_current_setpoint(channel: int) → float[source]#: Query the configured current-limit setpoint (amperes) on channel. Output may vary from actual measured current outside of constant current mode.

get_operating_mode( channel: int, ) → OperatingMode[source]#: Query whether channel is regulating in constant voltage, constant current, unregulated, or off.

set_overvoltage_protection_level( voltage: float, channel: int, ) → None[source]#: Set the overvoltage protection threshold (volts) on channel.

get_overvoltage_protection_level(channel: int) → float[source]#: Query the overvoltage protection threshold (volts) on channel.

set_overvoltage_protection_enabled( enabled: bool, channel: int, ) → None[source]#: Enable or disable overvoltage protection on channel.

get_overvoltage_protection_enabled(channel: int) → bool[source]#: Query whether overvoltage protection is enabled on channel.

set_overvoltage_protection_delay( delay: float, channel: int, ) → None[source]#: Stored; protection trips without delay.

get_overvoltage_protection_delay(channel: int) → float[source]#: Query the overvoltage protection trip delay (seconds) on channel.

set_overcurrent_protection_level( current: float, channel: int, ) → None[source]#: Set the overcurrent protection threshold (amperes) on channel.

get_overcurrent_protection_level(channel: int) → float[source]#: Query the overcurrent protection threshold (amperes) on channel.

set_overcurrent_protection_enabled( enabled: bool, channel: int, ) → None[source]#: Enable or disable overcurrent protection on channel.

get_overcurrent_protection_enabled(channel: int) → bool[source]#: Query whether overcurrent protection is enabled on channel.

clear_protection(channel: int) → None[source]#: Clear every latched protection trip on channel. The output stays off until re-enabled.

get_overvoltage_protection_tripped(channel: int) → bool[source]#: Query whether overvoltage protection has tripped on channel and not been cleared.

get_overcurrent_protection_tripped(channel: int) → bool[source]#: Query whether overcurrent protection has tripped on channel and not been cleared.

set_remote_sense_enabled(enabled: bool, channel: int) → None[source]#: Stored; the virtual load has no lead resistance, so readings are unchanged.

get_remote_sense_enabled(channel: int) → bool[source]#: Query whether remote sense is enabled on channel.