emeas — self-contained electrical measurement toolkit

Control a benchtop electrical measurement setup (Yokogawa GS200 source meters and HP/Agilent 34401A multimeters) over GPIB. Each instrument is represented by its own named object, so measurement scripts stay easy to read:

Y1.get_name()   # -> "source-drain bias"
HP1.read()      # -> gain-corrected reading

emeas has been validated against real Yokogawa GS200 and HP 34401A instruments in a live lab environment over the course of several years.

Quickstart (dummy mode)

from emeas import YokogawaGS200, HP34401A, DummyTransport, linear_sweep
from emeas.dummy import ResistorModel

dut = ResistorModel(resistance=1e6)
Y1 = YokogawaGS200(DummyTransport(dut), name="source-drain bias")
HP1 = HP34401A(DummyTransport(dut), name="drain reading", gain=1.0)

df = linear_sweep(Y1, HP1, start=-1, stop=1, points=51)
print(df.head())

A 2D current map with the side gate held fixed:

from emeas import map_2d
import numpy as np

df = map_2d(
    Y_bias,
    Y_gate,
    HP1,
    x_vals=np.linspace(-1, 1, 51),
    y_vals=np.linspace(-2, 2, 41),
    fixed={Y_sidegate: 0.5},
)

grid = df.pivot(
    index=Y_gate.get_name(),
    columns=Y_bias.get_name(),
    values=HP1.get_name(),
)

Live GUI and HDF5 storage

A PyQt6 + pyqtgraph GUI streams measurements into a live plot while saving every point to an HDF5 database together with the instrument settings used for that run.

uv sync --extra gui          # or: pip install -e .[gui]
emeas-gui                    # writes ./emeas_data.h5
emeas-gui my_fridge.h5       # custom database path

The GUI has three tabs:

• Instruments — Used to keep track of instruments. Can be discovered automatically by sweeping the network for GPIB devices, or by manually defining them.

• Measure — Run either a 1D sweep or a 2D map, configure the sweep parameters, add an optional label and tags, then start or stop the measurement. Acquisition runs in a background QThread, keeping the interface responsive, while each point is written to the HDF5 file as soon as it's collected.

• Browse — View saved runs in a sortable, filterable table. Selecting a run replots the data and displays the complete instrument settings snapshot. You can filter by label, measurement type, or tags, rename runs, edit tags, export data to CSV, or switch databases via File ▸ Open database.... For 1D data, the viewer also supports x-axis selection, per-trace visibility toggles, and a rolling-average overlay.

Streaming measurements from scripts

The generators used by the GUI can also be used directly:

from emeas import iter_linear_sweep
from emeas.storage import H5Store

with H5Store("data.h5") as store:
    run = store.new_run(
        "1d",
        "first cooldown",
        params={"start": -1, "stop": 1, "points": 51},
        instruments={"source": Y1, "meter": HP1},
    )

    for point in iter_linear_sweep(Y1, HP1, -1, 1, 51):
        run.append(point)

    run.close()

HDF5 layout

/                       attrs: emeas_version, next_run_number
/runs/run_00001/        attrs: run_number, label, kind, created_iso,
                                params(JSON), notes, tags
        data/           resizable datasets, appended one point at a time
        settings/<role>/ attrs: instrument settings() snapshots

Using real hardware

from emeas import VisaTransport

Y1 = YokogawaGS200(
    VisaTransport("GPIB0::3::INSTR"),
    name="source-drain bias",
)

Command syntax, operating ranges, and data accuracy have been validated against real instruments on a live GPIB bus — Yokogawa GS200 and HP 34401A.

The 34401A defaults to a 10 MΩ DC-voltage input impedance. For measurements on the 100 mV, 1 V, or 10 V ranges, pass high_impedance=True to enable the instrument's >10 GΩ input mode.

Per-instrument corrections

Calibration and measurement corrections belong to the instrument objects and are applied automatically.

Instrument	Parameters
VoltageSource	voltage_range, series_resistance
Multimeter	gain, series_resistance, input_impedance, voltage_range

• meter.read_raw() returns the instrument reading.
• meter.read() removes the configured amplifier gain.
• meter.read_current() converts a shunt voltage into current.

Development

uv sync --extra dev      # or: pip install -e .[dev]
uv run pytest            # or: pytest

QT_QPA_PLATFORM=offscreen pytest

Docker - not for PyQt based GUI

docker build -t emeas .
docker run --rm emeas

To use GPIB hardware inside a container, the host's VISA backend and USB-GPIB device need to be made available to the container.