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Control electronic loads to sink current in various modes for testing power systems.

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Import

from lager import Net, NetType

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Methods

The Net-based API provides methods that can either get or set values. When called without a value parameter, methods read and return the current value. When called with a value, they set it.
MethodDescription
mode(mode_type)Set or read operation mode (CC/CV/CR/CW)
current(value)Set or read constant current (A)
voltage(value)Set or read constant voltage (V)
resistance(value)Set or read constant resistance (ohms)
power(value)Set or read constant power (W)
enable()Enable electronic load input
disable()Disable electronic load input
print_state()Print comprehensive state
measured_voltage()Read measured voltage (returns float)
measured_current()Read measured current (returns float)
measured_power()Read measured power (returns float)

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Method Reference

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Net.get(name, type=NetType.ELoad)

Get an electronic load net by name. 
from lager import Net, NetType

eload = Net.get('LOAD', type=NetType.ELoad)
Parameters:
ParameterTypeDescription
namestrName of the electronic load net
typeNetTypeMust be NetType.ELoad
Returns: Electronic load Net instance

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mode(mode_type=None)

Set or read the operation mode. 
# Set mode
eload.mode('CC')  # Constant Current
eload.mode('CV')  # Constant Voltage
eload.mode('CR')  # Constant Resistance
eload.mode('CW')  # Constant Power (also 'CP')

# Read current mode
current_mode = eload.mode()
print(f"Mode: {current_mode}")
Parameters:
ParameterTypeDescription
mode_typestr or None’CC’, ‘CV’, ‘CR’, or ‘CW’/‘CP’. If None, reads current mode.
Returns: Current mode string if mode_type is None

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current(value=None)

Set or read the constant current setting. 
# Set CC mode current
eload.mode('CC')
eload.current(0.5)  # Set to 500mA

# Read current setting
i = eload.current()
print(f"Current setting: {i}A")
Parameters:
ParameterTypeDescription
valuefloat or NoneCurrent in amps. If None, reads current setting.
Returns: Current setting in amps if value is None

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voltage(value=None)

Set or read the constant voltage setting. 
# Set CV mode voltage
eload.mode('CV')
eload.voltage(5.0)  # Set to 5V

# Read voltage setting
v = eload.voltage()
print(f"Voltage setting: {v}V")

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resistance(value=None)

Set or read the constant resistance setting. 
# Set CR mode resistance
eload.mode('CR')
eload.resistance(100.0)  # Set to 100 ohms

# Read resistance setting
r = eload.resistance()
print(f"Resistance setting: {r} ohms")

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power(value=None)

Set or read the constant power setting. 
# Set CW mode power
eload.mode('CW')
eload.power(5.0)  # Set to 5W

# Read power setting
p = eload.power()
print(f"Power setting: {p}W")

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enable() / disable()

Enable or disable the electronic load input. 
eload.enable()   # Start sinking current
eload.disable()  # Stop sinking current
Print comprehensive electronic load state. 
eload.print_state()
# Prints: mode, current/voltage/resistance/power settings, measured values, input state

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measured_voltage() / measured_current() / measured_power()

Read actual measured values (return floats, for use in code). 
v = eload.measured_voltage()  # Returns measured voltage
i = eload.measured_current()  # Returns measured current
p = eload.measured_power()    # Returns measured power

print(f"V={v:.2f}V, I={i:.3f}A, P={p:.3f}W")
Returns: float - Measured value

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Load Modes

ModeCodeDescription
Constant CurrentCCSinks a fixed current regardless of voltage
Constant VoltageCVMaintains a fixed voltage across the load
Constant ResistanceCRBehaves as a fixed resistance
Constant PowerCW or CPDissipates a fixed power

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Examples

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Constant Current Test

from lager import Net, NetType

eload = Net.get('LOAD', type=NetType.ELoad)

# Configure constant current mode at 500mA
eload.mode('CC')
eload.current(0.5)

eload.enable()

# Read measurements
print(f"Voltage: {eload.measured_voltage():.2f}V")
print(f"Current: {eload.measured_current():.3f}A")
print(f"Power: {eload.measured_power():.3f}W")

eload.disable()

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Battery Discharge Test

from lager import Net, NetType
import time

eload = Net.get('LOAD', type=NetType.ELoad)

# Configure constant resistance load
eload.mode('CR')
eload.resistance(10.0)

eload.enable()

# Monitor discharge
for i in range(30):
    v = eload.measured_voltage()
    i_curr = eload.measured_current()
    print(f"V={v:.2f}V, I={i_curr:.3f}A")

    if v < 3.0:
        print("Discharge cutoff reached")
        break

    time.sleep(1)

eload.disable()

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Power Efficiency Test

from lager import Net, NetType

# Input power supply
psu = Net.get('INPUT', type=NetType.PowerSupply)
psu.voltage(12.0)
psu.current(2.0)
psu.enable()

# Output load
eload = Net.get('OUTPUT', type=NetType.ELoad)
eload.mode('CC')
eload.current(0.5)
eload.enable()

# Measure efficiency
p_in = 12.0 * psu.measured_current()  # Input power
p_out = eload.measured_power()         # Output power
efficiency = (p_out / p_in) * 100 if p_in > 0 else 0

print(f"Input: {p_in:.2f}W")
print(f"Output: {p_out:.2f}W")
print(f"Efficiency: {efficiency:.1f}%")

eload.disable()
psu.disable()

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Supported Hardware

ManufacturerModelFeatures
RigolDL3000 seriesCC/CV/CR/CP modes

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Notes

  • Use mode() to set the operation mode before setting the corresponding value
  • Methods like current(), voltage(), resistance(), power() can get or set values
  • measured_voltage(), measured_current(), measured_power() return actual measurements
  • print_state() prints state (for debugging), measurement methods return values (for code)
  • Always call enable() to start sinking current
  • Always call disable() when finished