Support for generic DMM and T&M instrument IEXTs

[ammaree]

Background

The above request comes from my effort to add support for the Keysight 34465A DMM using Clause AI.
The basic support is working but we came across the limitations below in the process of expanding functionality.# Feature Request:

Additional physical unit support for generic DMM and T&M instrument IEXTs

Summary

The UNITS object in packages/eez-studio-shared/units.ts currently covers electrical power and signal units well, but is missing several physical measurement units that are essential for bench DMMs, LCR meters, and general-purpose instruments. This causes the waveform renderer to crash (Error while rendering history item N!) when session.addChart() is called with a unit string that is not a key in UNITS.

Current state

UNITS keys as of the current codebase:

time, volt, voltage, amp, ampere, amperage, current,
watt, wattage, power, frequency, "sampling rate",
decibel, joule, unknown, unkn

Problem

A bench DMM — for example a Keysight 34465A or Rigol DM3058 — measures resistance, capacitance, temperature, and period in addition to voltage, current, and frequency. When an IEXT shortcut script calls session.addChart() with unit: "ohm" or unit: "celsius", the renderer looks up UNITS[unitName] and receives undefined. Any subsequent call to undefined.formatValue() throws, and the React error boundary catches it, displaying "Error while rendering history item N!" with no recovery path short of deleting the session entry.

The only current workaround is unit: "unknown", which silently drops axis labelling and SI prefix formatting for the user.

Requested additions

Resistance

ohm:     OHM_UNIT,      // Ω — SI prefix formatted: mΩ, Ω, kΩ, MΩ, GΩ

Needed for: 2-wire resistance, 4-wire (Kelvin) resistance, continuity threshold, diode forward voltage (secondary).

Capacitance

farad:       FARAD_UNIT,   // F — SI prefix formatted: pF, nF, µF, mF, F
capacitance: FARAD_UNIT,   // alias

Needed for: capacitance measurement on DMMs and LCR meters.

Temperature

celsius:    CELSIUS_UNIT,     // °C
fahrenheit: FAHRENHEIT_UNIT,  // °F
kelvin:     KELVIN_UNIT,      // K

Needed for: thermocouple, RTD, and thermistor measurements on DMMs and temperature loggers.

Period / time (sub-second)

time exists but the formatting and SI prefix support at sub-second resolution (ps, ns, µs, ms) would benefit from explicit aliases if the current TIME_UNIT formatter does not already handle them:

second: TIME_UNIT,   // s — alias to confirm SI prefix support for ps/ns/µs/ms
period: TIME_UNIT,   // alias for DMM period measurement context

Suggested implementation

Each new unit follows the same pattern as existing units. Example for resistance:

// units.ts

const OHM_UNIT: IUnit = {
    name: "ohm",
    color: "#4CAF50",
    colorInverse: "#2E7D32",
    label: "Ω",
    units: {
        "": { label: "Ω", conversion: 1 },
        m: { label: "mΩ", conversion: 1e-3 },
        k: { label: "kΩ", conversion: 1e3 },
        M: { label: "MΩ", conversion: 1e6 },
        G: { label: "GΩ", conversion: 1e9 }
    },
    formatValue(value: number, precision = 4) {
        // SI prefix selection identical to VOLTAGE_UNIT pattern
        ...
    }
};

// In UNITS:
ohm:         OHM_UNIT,
resistance:  OHM_UNIT,

const FARAD_UNIT: IUnit = {
    name: "farad",
    label: "F",
    units: {
        p: { label: "pF", conversion: 1e-12 },
        n: { label: "nF", conversion: 1e-9 },
        u: { label: "µF", conversion: 1e-6 },
        m: { label: "mF", conversion: 1e-3 },
        "": { label: "F",  conversion: 1 }
    },
    ...
};

// In UNITS:
farad:       FARAD_UNIT,
capacitance: FARAD_UNIT,

const CELSIUS_UNIT: IUnit = {
    name: "celsius",
    label: "°C",
    units: { "": { label: "°C", conversion: 1 } },
    formatValue(value, precision = 4) {
        return value.toPrecision(precision) + " °C";
    }
};

// Similarly for fahrenheit, kelvin.
// In UNITS:
celsius:    CELSIUS_UNIT,
fahrenheit: FAHRENHEIT_UNIT,
kelvin:     KELVIN_UNIT,

Impact

• Unblocks IEXT authors writing DMM, LCR meter, and temperature logger extensions from having to fall back to "unknown" for all non-electrical quantities
• Eliminates the renderer crash that currently occurs when an unsupported unit string is passed to session.addChart()
• Aligns EEZ Studio's unit support with the full measurement capability of general-purpose bench instruments

References

• packages/eez-studio-shared/units.ts — UNITS object and IUnit interface
• packages/eez-studio-ui/chart/value-accesor.ts — initValuesAccesor (unit consumed here)
• packages/eez-studio-ui/chart/WaveformFormat.tsx — WaveformFormat enum
• packages/instrument/window/script.ts — addChart() implementation (line ~169), unitName: config.unit.toLowerCase()
• packages/instrument/window/history/items/generic.tsx — isWaveform(), renderer entry point

Testing

A minimal reproduction with a generic SCPI instrument:

// In an IEXT shortcut JS script — currently crashes renderer with "ohm":
session.addChart({
    data: [new Uint8Array(new Float64Array([1000, 1001, 999, 1002]).buffer)],
    format: 8,          // FLOATS_64BIT
    unit: "ohm",        // CRASHES: UNITS["ohm"] === undefined
    samplingRate: 1,
    offset: 0,
    scale: 1,
    ...
});

// Workaround (loses axis label):
session.addChart({ ..., unit: "unknown" });

[mvladic]

Implemented. Thanks!

[ammaree]

Thanks for the quick response. When will this be available in a new release?

[mvladic]

Next release will be soon, within couple of weeks.

[ammaree]

Have the basic DMM working, just waiting for the additional support. In the process have come across a couple more items:

1. Mechanism for organising layout of "toaster" window, have tried "
   " and '\n" no luck. For use to display groups of data such as line 1: [Mode, resolution, sample count], Line 2 [RMS Min/Cur/Max], Line 3 [P-P Min/Cur/Max] on 3 separate lines
2. Support of 24hr time setting
3. Support for other date formats, mainly YY/MM/DD and/or CCYY/MM/DD

Also busy with Rigol MHO98 support.

[ammaree]

Initial Rigol MHO98 support working.

Have added support for old (2012) EA-PS2000 series PSU. Automatically detects the model and adjust accordingly. Uses python script in background to make available as local device on port.

Will soon create repo on Github for them, welcome to incorporate from there.

The toaster popup window obscures the "Stop" button for a live running script. Any chance to reorg the layout so the button can be accessed?

Also any way to enable 2 ( or maybe up to 4) column support in the dialog box. This will allow creation of menus for both PSU channels, both AWG channels or maybe even all 4 scope channels next to one another with rows below for each configurable value.