Dip Measurement Core Algorithm

Core 4-wire resistance measurement module using current reversal technique for high-accuracy offset-compensated measurements.

Instruments

• Keithley K2450 SourceMeter — programmable current source
• DAQ6510 with 7702 Multiplexer — multi-channel voltage measurement

Features

• Current reversal technique: V_true = (V+ − V−) / 2 to cancel thermal EMF
• 4-wire relay addressing on 7702 multiplexer (up to 20 channels)
• Dynamic per-channel current calibration to target 2 mV excitation
• PT100/PT1000 resistance-to-temperature conversion
• Support for PT1000, PT100, Thermistor, Diode, and Zirconium Oxynitride sensors

Installation

From PyPI (after publishing)

pip install dip-measurement-core

From GitHub

pip install git+https://github.com/YOUR_USERNAME/dip-measurement-core.git

Local development install

git clone https://github.com/YOUR_USERNAME/dip-measurement-core.git
cd dip-measurement-core
pip install -e .

Dependencies

• numpy
• ki488 — GPIB interface layer
• k2450-gpib — Keithley K2450 driver
• daq-gpib — DAQ6510 driver

Note: The ki488, k2450-gpib, and daq-gpib packages must also be pip-installable (either on PyPI or installable via pip install git+https://...).

Quick Start

from dip_measurement_core import DipMeasurement

dip = DipMeasurement()

# Connect to instruments via GPIB
success, msg = dip.connect(k2450_address=18, daq_address=20)

# Configure measurement
dip.configure(current_ma=0.1, sensor_type='ZIRCONIUM')

# Measure a single channel
result = dip.measure_channel(1)
print(f"Channel 1: {result['resistance']:.4f} Ω")

# Measure multiple channels
results = dip.measure_all_channels([1, 2, 3, 4, 5])
for ch, data in sorted(results.items()):
    print(f"  Ch {ch}: R={data['resistance']:.4f} Ω")

# Disconnect
dip.disconnect()

Dynamic Current Calibration

To automatically adjust excitation current per channel (targeting 2 mV):

dip.configure(current_ma=0.01, dynamic_current=True)
success, msg = dip.calibrate_currents(channels=[1, 2, 3, 4, 5])
print(msg)

# Subsequent measurements use calibrated currents
results = dip.measure_all_channels([1, 2, 3, 4, 5])

Publishing to PyPI

# Install build tools
pip install build twine

# Build the package
python -m build

# Upload to PyPI (you'll need a PyPI account and API token)
python -m twine upload dist/*

License

MIT