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ohmSTAR Companion · Windows, macOS, Linux

Your decade box,on an ego trip.

The ohmSTAR Companion is the desktop app for the ohmSTAR and ohmSTAR+. It draws the box's own display and keypad on your screen, then takes over the work: sensor curves, sweeps, strain profiles, pass/fail sequences, logging, scripting and an AI assistant that runs the box from a sentence. Set it up once and it basically automates itself. Every clip on this page is a real session, recorded in the app.

Firmware

Works with firmware 7.x and later. On an older box? Send it in once: we upgrade it to the newest firmware, and a calibration includes the upgrade free. After that, every update comes through the app.

Send it in for an upgrade
Download for Windows Mac, Apple chip Mac, Intel chip Linux Legacy software (before Windows 10)

ALLOne app for the whole bench

Whatever your bench needs, it's already in here.

Sensor curves, sweeps, strain profiles, pass/fail sequences, logging, scripting, an AI assistant and a calibration bench, in one app that connects to the box by itself.

  • Ready when you plug in

    The app finds the box and reads in its 14 memories, settings and calibration record. No box yet? Mock ohmSTAR+ lets you learn the app first.

  • Hard to get wrong

    Type 4700, 10k or 1.5M. Every value is checked against your model before it's sent; out of range is refused, with the reason.

  • Runs the boring parts

    Sweeps, pass/fail sequences and CSV logging run unattended. The AI assistant runs the box from a sentence, and asks before it acts.

  • Calibrate it yourself

    Free, at your own bench, with a 34401A meter. The signed record goes into the box and the certificate is made for you. How it works

Missing something? We'll build it.

Tell us what your bench needs, and our in-house software team can add it.

Suggest a feature
Quick values and Box settings. The folded panels below the keypad are opened one at a time. Each button press shows up in the console as the command it sent.

01Device page

Full control of the ohmSTAR, with all your settings at your fingertips.

The Device page is the box itself, with a mouse. Type a value and the display answers; open the panels below it and the box's 14 memories, its settings and its calibration record read themselves in. Nothing to transcribe, nothing to remember. Switch to compact mode for a persistent ohmSTAR window on your desktop, with two-way communication.

Use it for

  • Bench work by hand
  • Setting I set before connecting a circuit
  • Checking the box's calibration record
  • Loading the 14 memories for a technician
Temperature to ohms. A Pt100 α0.00385, then a 10 kΩ NTC. The slider's colour runs cold blue to hot red; the curve on the right marks your point.

02Temperature to ohms

Think in degrees. The box outputs the ohms.

This is the page a controls engineer lives on. Pick the sensor the controller expects, type the temperature you want the controller to believe, and the box becomes that sensor at that temperature. The curve maths, the rounding, the range check: all done for you before anything is sent.

Use it for

  • Thermostat and PID set-point checks
  • HVAC and refrigeration controllers
  • Process alarms (high, low, open)
  • Teaching RTD vs thermistor curves
Temperature slider on the Device pageThe slider only writes when you let go, and only after Unlock is ticked. Dragged across −127 °C to 640 °C on a Pt100, then on a 10 kΩ NTC. The caption under it reports the exact ohms sent and the nearest step.
Sensor library. 128 curves: RTDs, thermistors, strain gauges and potentiometers, from the makers' published tables.

03Sensor library

128 sensors, searchable, plotted, and one click from the box.

The library is where every sensor feature starts. Search by name, type or maker; the curve, its range and its maker's document are right there. No tables to type in, ever: 128 sensors, already verified, one click from the box.

Use it for

  • Finding the exact curve a controller expects
  • Comparing sensor families
  • Checking a range before a test
Sensor to box: table upload. A Pt1000 goes into slot 9, is read back, and compared point by point.

Put the curve in the box, so it works without a computer.

The box can hold nine user tables. With one loaded and selected at the keypad, the box reads temperatures directly: a technician types 25 and the output becomes 109.74 Ω.

Sweeps. A Pt100 span check: 0 → 100 °C in quarters, 10 s each. The display reads SWEEP IN PROGRESS and shows the current °C.

04Sweeps

A range and a step, in ohms or in degrees. Walk it, watch it.

A sweep is the Companion's workhorse, and the clearest case of the app doing the job for you. Set a range, a step and a hold, press Start, and walk away: up to 5,000 values a pass, looped up to 100,000 times, held from 0.3 s to 24 h each, every one logged. Resistance, temperature or strain; six shapes.

Use it for

  • Span and linearity checks
  • Alarm trip points
  • Thermal cycling (triangle, sine)
  • Ramps for ATE
  • Soak tests up to 24 h
Strain gauges. A 120 Ω, GF 2 gauge ramped 0 → 2000 µε and back. The display shows the ohms, with µε on its lower line.

05Strain gauges

Microstrain in, ohms out. The ohmSTAR+ was built for this.

A 120 Ω gauge at 1000 µε is 120.24 Ω: a quarter of an ohm. That's why the ohmSTAR+ steps in 0.01 Ω. This page takes a gauge resistance, a gauge factor and a lead resistance, turns a strain profile into those tiny steps, and runs it, ten cycles or ten thousand, while you do something else.

Use it for

  • Load-cell and strain-amplifier checks
  • Bridge-completion testing
  • Fatigue rigs: repeated cycles
  • Teaching the gauge equation
350 Ω gauge, 10 fatigue cycles±500 µε, 10 steps a loop, 10 loops: 100 values, about 1 min 40 s. The display counts STEP 9 OF 10, LOOP 1 OF 10; the graph shows the whole train of cycles. 349.65 Ω at −500 µε, 350.35 Ω at +500 µε.
Sequences and reports. “Heater controller check (Pt1000, 60 °C set point)”: seven steps, each with a reading and a verdict, then a PASS report.

06Sequences and reports

A test procedure that runs itself and writes the report.

A sequence is a test procedure that runs itself. Write the steps once: a resistance or a sensor value, a label, and what to check. The app sets each one, you type what the equipment showed and mark Pass, Fail or Skip, and the report writes itself, every run, every time.

Use it for

  • Incoming inspection
  • Controller acceptance tests
  • Graded lab exercises
  • Repeatable field checks
Custom tables. A fuel level sender, 240 Ω empty → 33 Ω full, run as 11 points. The display reads TABLE IN PROGRESS and the percent.

07Custom tables

Any resistive sensor, even one that isn't in a library.

A table is two columns: the sensor's unit and the ohms. Build one from a formula, load a two-column CSV, or start from a library sensor. Then run it from the app, or store it in the box so the box runs it with no computer at all.

Use it for

  • Fuel, level and position senders
  • Potentiometers and rheostats
  • Odd thermistors by Beta or Steinhart–Hart
  • RTDs by R0 (Callendar–Van Dusen)
CSV logging. Logging is on; a sweep runs on the Sweeps page; the log page shows every value as it arrives, as a graph or as the file itself.

08CSV logging

Every value sent, in a file you can open in Excel.

Switch logging on once and forget it. The app writes one file a day, ohmstar-YYYY-MM-DD.csv, with every value from every page: sweeps, sequences, the slider, the command line, the AI. Nothing to remember to start, nothing to export.

Use it for

  • Evidence for a test report
  • Correlating with a DAQ's own log
  • Audit trail of what a box was set to
Command-line tool. info, set 4.7k, temp pt100 25, sensors 10k. The same commands come as a separate ohmstar tool for scripts.

09Command line, network API, several boxes

For the engineer who'd rather type. Or script. Or both.

Three ways to put the box inside your own automation, all through the Companion's connection, so they never fight over the serial port. A test station, a LabVIEW rig or a cron job can own the box as easily as a person can.

Use it for

  • Shell scripts and test stations
  • LabVIEW, MATLAB, TestStand via HTTP
  • Several boxes from one script
Local network APIPress Start and the app serves HTTP on port 8765: GET /v1/state, POST /v1/resistance, POST /v1/sensor, GET /v1/sensors. A bearer token guards it; Allow AI control (MCP) adds the /mcp route. Setup lines for Terminal, PowerShell, Claude Code, Codex and Claude Desktop are ready to copy.
AI assistant. Claude reads the box, builds a thermistor from Steinhart–Hart coefficients, previews a sweep, asks before sending it, runs it, and explains the numbers.

10AI assistant

AI approved

Say what you want. It plans it, shows you, and asks.

This is where the app stops needing an expert at all. Describe the test; the assistant defines the sensor, plans the sweep, previews it and runs it. It's a language model with hands on the box, on a short leash: before anything changes, it shows exactly what it will send and waits for Allow. Stopping a sweep never asks.

Models

  • Claude
  • OpenAI
  • Gemini
  • DeepSeek
  • Mistral
  • xAI
  • Groq
  • Together
  • OpenRouter
  • Ollama
  • LM Studio
  • llama.cpp
  • vLLM
Settings and the calibration bench. The Cal lab preset switches the bench on. A unit is calibrated against a reference meter and the signed record is written into the box.

11Settings and the calibration bench

Switch on only what your bench needs. Including a cal lab.

Settings is where the side bar is shaped. Presets switch pages on and off in groups; one of them, Cal lab, adds a whole second tab for calibrating boxes against a reference multimeter, in Auto mode, with the certificate written and signed for you.

Use it for

  • In-house calibration, signed by your lab
  • A locked-down bench computer (Just the box)
  • A teaching bench (Standard)
Light and dark mode. Dark, Light, or Match this computer. Every page follows, including the drawn display's bezel.

12Light, dark and compact

Fits the room, and fits the corner of a screen.

Two small things that matter on a real bench: a light theme for a bright lab, and a compact window that stays on top of your DAQ software.

Use it for

  • Bright labs and classrooms
  • Projecting for a class
  • Night shifts
Compact window. Press Compact in the status bar.

The compact window: just the box, always on top.

A phone-shaped window with only the display, the keypad and Set resistance or temperature. Tick Keep on top and it floats over LabVIEW, a terminal or a browser while you work. Full window brings everything back.

FWohmSTAR and ohmSTAR+

Firmware 7.x

Firmware 7.x adds a bootloader: the last flash with a programmer. After it, every update goes over USB from the Companion, and a failed update can always be retried. It takes about 3–4 minutes. Calibration, serial and the stored record are never touched.

Stuck in update mode? Hold M at power-on, then press the repair button in the app.

Also in firmware 7.x

  • 7.xThe box reports what its output really is after each value, and whether a table is active. Serial and calibration dates stored on the box, shown under About. All 14 memories and quick keys readable and storable from the app without moving the output. Standby delay and display settings from the app. High efficiency (display-off) mode. USB firmware updates. Knob pickers on I set and Step. A memory list and a table list chosen by knob. Scrolling menus with a marker.
Box settings during a firmware update: firmware being written over USB at 46 percent, less than a minute left, with a reminder to keep the USB cable connected.
A firmware update over USB, from Box settings.

Guard rails

Smart, on a short leash.

An app that runs the box for you needs rules. These are hard limits on what any script or AI can do with it, and every AI action is logged in the app.

An AI or the HTTP API can never reach

  • Calibration
  • The calibration record and its signature
  • Serial and dates
  • Keys
  • Firmware
  • Raw commands
  • Factory reset

Limits on a sweep

Values per pass
5,000
Per step
0.3 s–24 h
Loops
100,000

AI sweeps are tighter: 1,000 values a pass, 100 loops, 10,000 values in all, 24 h. Refused while a calibration, a table upload or a firmware update has the box, or while a table is active on it.

Download the Companion

For ohmSTAR and ohmSTAR+. Firmware updates are built in and run themselves over USB. No box yet? The mock box lets you try every page.

Windows

ohmSTAR Companion for Windows

Windows 10 or later, x64. Not signed yet: choose More info, Run anyway.

Download for Windows

Closed-source. The installed app refuses debugging back doors, and its signing keys are sealed by the operating system.

Scripting, the HTTP API, Python and the short PDF guides: Resources. Questions: contact support.