What is it?

A high-precision 4-wire ohmmeter designed for low-resistance measurements up to 100 mΩ full scale, with 2 µΩ resolution.

Why did you make it?

One of my clients needed a way to measure changes in the contact resistance of automotive connectors over a large number of insertion cycles. The challenge was that he needed a resolution of a few micro-ohms, and the device had to be small, robust, and inexpensive relative to its performance.

What makes it special?

• True 4-wire (Kelvin) measurement
• Full-scale: 100 mΩ, resolution: < 2 µΩ
• USB-C virtual COM port, 9600 baud
• SCPI-style command set
• Individually calibrated and verified before shipping

How to use it ?

Communication is handled via USB serial interface using standard SCPI-style commands, making it easy to automate measurements from Python or LabView. Supported commands:

• IDN?\n Returns the device name, version, and serial number.
• MEASURE\n Performs a resistance measurement, then returns the measured value in micro-ohms.

You must connect a DC power supply between 5 V and 24 V, capable of supplying at least 3 W. USB is not used to supply power to the resistor being measured.

[!] USB-C cable and power supply are not included