Your instruments can do more than their front panel shows

A power supply without a watt readout

The Tenma 72-2540 on our test bench - the same design as the Korad KA3005P, Velleman PS3005D and RND 320-KA3005P - has two displays: volts and amps. No watts. When you test a converter, a heater, an LED string or a motor, power is often the number you actually want, so you multiply in your head or on a calculator.

The supply already measures both factors. BenchMesh reads them over USB and shows output power on the panel, next to voltage and current, calculated as P = V x I from the supply's own measurements. It is a reading like the others: you can record it, use it in a flow ("stop when the power exceeds 20 W") or read it from MATLAB and Python.

The Tenma is not an exception. Of the twelve power supply families we compared, from the cheapest to the professional, only seven measure power themselves. With BenchMesh all twelve show it - the Korad KA series and its rebrands, the OWON ODP, Siglent SPD3303X, Manson HCS, Hantek PPS and Juntek DPM86xx included. Where an instrument measures power itself, its own value is shown instead.

That is the general idea of this post: the value software adds is largest exactly where the instruments are cheapest.

Readings the instrument does not show

Power is the simplest case of a value calculated from what the instrument already reports. Others available today:

The OWON DGE2070 is a good example of the second row: its SCPI interface sets frequency, Vpp and offset only, so a period, a level in Vrms or dBm, or high and low levels have to be converted before they are sent. BenchMesh does the conversion, so you enter the value in the unit your circuit needs.

The same front-panel functions on every instrument

Multimeters are a different story. Almost all of them have relative mode, min / max and similar functions somewhere - but spelled seven different ways, behind different buttons, and mostly out of reach from a computer. BenchMesh gives every meter the same set on its panel, for example the OWON XDM1241 on our bench:

• MIN, MAX and AVG of the readings since you started, restarted when you change function.
• Hold to freeze a reading and Rel Δ to show the difference from a reference.
• A bar graph of the reading against the range, the analogue needle many bench meters lack.

Spectrum analyzers such as the tinySA Ultra get a max-hold trace and a peak readout on the BenchMesh screen, the same on every analyzer. And every instrument gets the same kind of panel whoever made it, plus a command console with history for the moments you want to talk to it directly.

A data logger for every instrument

Expensive instruments have a data logger built in: a top-end multimeter records thousands of readings with trend charts and statistics, a professional supply logs its output to internal memory or a USB stick. Budget instruments have nothing of the kind - and even the expensive ones record only themselves.

BenchMesh records any reading of any instrument on one shared timeline: the supply's voltage, current and calculated power, the meter's reading and the load's current, sampled on a common time grid and exported to CSV or loaded into pandas. A meter that cost less than a lunch for the team and a load that cost a few hundred logs side by side, as one data set. That is one feature where the cheap bench now does more than a single top-end instrument: the logger covers the whole experiment, not one box.

Sequences for instruments with only a knob

Professional supplies and loads have list mode, ramps, timers and built-in battery tests. The Tenma has a knob and a memory button. BenchMesh flows add the sequence on the computer side, so they work with any supply or load it controls:

• List and ramp: step the voltage from 1 V to 12 V in 0.5 V steps, holding each for ten seconds, and record the whole run.
• Repeat until: keep a step going until a reading crosses a value - the battery reaches 3.0 V, the meter reads 5 V.
• Battery discharge: draw a constant current with the OWON OEL1515, record the voltage and switch the input off at the cut-off.
• Decide and loop: repeat a test, branch on a result, sweep a second instrument.

You can build a flow by hand, or describe it in plain words and let a model of your choice assemble it. Every step that can switch an output on needs your confirmation before the run starts.

What software cannot add

Software works with the readings the instrument gives it, so a few things stay with the hardware:

• Accuracy and resolution. A calculated power is as accurate as the voltage and current behind it; statistics are as good as the readings.
• Speed. A serial supply answers a few times a second. Software statistics, logs and sequences work at that pace - fine for tests of minutes and hours, not for fast transients, where the instrument's own functions stay better.
• Protection. Hardware over-voltage and over-current protection reacts in microseconds; software reacts after the next reading and cannot act when the cable is pulled. Set the instrument's own OVP and OCP first.

Within those limits, the gap between what a budget instrument measures and what it shows is large - and software closes most of it.

Coming next

The next releases move the calculations onto the BenchMesh server, so every value is recorded, available to flows, MATLAB, Python and AI assistants, the same in every window, and labelled with where it comes from (instrument, calculated or software). Planned, in roughly this order:

The roadmap tracks what is in progress. If your instrument lacks a feature you need, tell us - the instruments with the fewest features are the ones that gain most.

Questions

Read more

Features need a connection first: why a USB or LAN port is worth paying for is in Do not buy instruments without connectivity means, and how to put a whole bench on the lab network is in Top-end instrument features for the instruments you already own.