200 years of legal metrology in Luxembourg

Did you know that Luxembourg’s law of August 21st 1816 made the metric system obligatory for all commercial transactions? I didn’t, until I was invited to the 200 year celebration “Bicentenaire de la Métrologie Légale”, which took place in Belval yesterday. The most prominent speaker, Luxembourg’s Deputy Prime Minister and Minister of the Economy Étienne Schneider, took this opportunity to announce that Luxembourg has decided to acquire an atomic clock.

Deputy Prime Minister and Minister of the Economy Étienne Schneider

Deputy Prime Minister and Minister of the Economy Étienne Schneider

Other speakers included ILNAS director Jean-Marie Reiff, BLM director Philippe Kadok, Professor Olivier Francis from the University of Luxembourg and Dr. Martin Milton, director of the BIPM. Mr. Kadok’s presentation contained a slide a few interesting facts about the Service de Métrologie Légale: In 2015, this relatively small sub-organization of the BLM verified 2861 petrol pumps and more than 1450 weighing instruments of all types throughout the country.

BLM director Philippe Kadok

BLM director Philippe Kadok

Several organizations with ties to the field of metrology had set up stands in the conference hall. The Service de Métrologie Légale’s stand showcased balances, weights and other measurement instruments. Sadly, recently retired director John Kirchen was nowhere to be seen.

Service de Métrologie Légale

Service de Métrologie Légale

A&D EK-610i balance used for density determination

A&D EK-610i balance used for density determination

Visitors were also invited to take a tour of ILNAS’ recently inaugurated EMC lab (used only for market surveillance purposes, not for product certification).



Free software for scales and balances with RS-232 and USB

Are you still manually entering weight readings from your scale or balance on your PC? Is your scale equipped with a RS-232 or USB (virtual COM port) interface? If yes, you can eliminate manual data entry by connecting your scale to your computer and using our free software 232key.

232key automatically types the weight into any application

Our software runs in the background, listens to the COM port (serial port) your scale is connected to and waits for measurement values sent by the scale. Those values are then filtered, formatted and typed into the application running in the foreground at the current cursor position as simulated keystrokes. This means that 232key can be used to transfer the weight (or other measurement values) into any application that accepts keyboard inputs, e.g. Microsoft Excel, OpenOffice / LibreOffice Calc, Google Docs, a form on a website, etc.

In the following example, I used A&D’s FG-60KBM scale with an optional RS-232 interface (FG-OP-23). I connected it to my laptop with A&D’s serial cable (AX-PC09-SCA) and an inexpensive converter to USB (as my laptop doesn’t have a serial port). Upon pressing the “PRINT” key on the scale, the weight was typed directly into an input field on a website:
Transferring the weight from a scale to a website

Compatibility with scales and balances

To use 232key, you’ll need a scale with a RS-232 interface (aka. serial port, COM port, EIA-232) or an interface which appears as a (virtual) COM port when the scale is connected to your PC. This is the case for many (but not all) scales with a USB interface and for scales which support the Bluetooth Serial Port Profile.

Your scale or balance also has to send the weight in ASCII format. The weight has to be the first numeric value sent* and it should only be sent once (after you’ve pressed a key on the scale), not continuously.

The vast majority of scales and balances available on the market today fulfills these requirements. Just to give you a few examples, you should be able to use 232key with most or all scales and balances made by A&D (RS-232 only), Adam Equipment (RS-232 and USB), Ohaus** (RS-232 and USB), Kern**, MyWeigh (RS-232 only) and other well-known brands. New device profiles are constantly added!

Finally, an easy way to transfer data from your scale to your PC

We designed 232key to make your life easier. No complicated configuration is required. If your scale manufacturer or model is included in the list of predefined devices, you don’t even have to manually enter the interface parameters: Simply select your scale and click on “Default” to load the settings.
Interface settings

Not sure which COM port you scale is connected to? Press the “Auto” button and 232key will try to detect the port automatically (works with all devices which have some sort of hardware handshaking functionality, e.g. scales and balances made by A&D and MyWeigh’s popular HD series).

Do you know which decimal separator (point or comma) your scale is using? Why should you! 232key understands both input formats and lets you choose which output format you want.
Decimal separator

Would you like 232key to press an additional key after typing the weight, e.g. the “Enter” key to jump to the next row in a spreadsheet? No problem, simply specify the desired key in the “Format” tab.
Additional key

All of these useful and user-friendly features are available for free! Additional functionality is available in the paid “Plus” version of 232key.

Download and documentation

Please visit our product website 232key for further information and to download our free software. Should you have any questions or suggestions, please don’t hesitate to post them in our support section or as a comment below.

* We’ve added an exception to this rule for scales and balances made by Adam Equipment.
** Affiliate links.

How accurate are smart scales?

Are smart scales accurate weighing instruments or just simple bathroom scales with expensive connectivity features? To find out, I tested the Withings WS-30, Fitbit Aria and A&D UC-324NFC using class M1 weights.


Each of the scales had not been used before and was configured as instructed by the manufacturer. This included signing up for an account with Withings and Fitbit. In the case of A&D’s UC-324NFC, I took advantage of a function available in the Wellness Connected  app which let me “calibrate” the scale by entering the local gravitational acceleration.

The scales were tested under similar conditions with a stable temperature of around 22°C and were placed on a flat, hard surface. The Withings and Fitbit scales were left alone for a night after the initial configuration as I wasn’t quite sure how they determine the zero value: unlike older electronic scales, you don’t have to switch them on and wait for them to show ‘zero’, instead, you step right on (the UC-324NFC determines the zero point after you step off).

Test procedure

I used 20kg weights to test the scales at 40, 60, 80, 100 and 120 kg. This procedure was repeated 3 times for each scale (I did a lot of weight lifting that day).


The first column gives you the nominal weight (in kg) and the next three are the values as shown by the scales.

Withings WS-30

40 40.2 40.2 40.2
60 60.3 60.3 60.3
80 80.4 80.3 80.3
100 100.3 100.4 100.4
120 120.4 120.4 120.4

Fitbit Aria

40 40.2 40.2 40.1
60 60.2 60.2 60.2
80 80.2 80.2 80.2
100 100.3 100.3 100.3
120 120.3 120.3 120.4


40 39.95 39.95 39.95
60 60.00 59.95 60.00
80 80.00 80.00 79.95
100 100.00 100.00 100.00
120 120.00 120.00 120.00

As you can see, A&D’s UC-324NFC was the most accurate scale, never deviating by more than 50g from the true value. Its 50g resolution and gravity compensation function certainly paid off.

However, the Fibit and Withings scales did a great job, too. Looking at the measurement results in each row, you’ll see that they are either identical or off by just one scale interval (100g). We can therefore say that these scales were slightly less accurate, but still very precise* (or that their repeatability was still excellent). As far as your body weight is concerned, you’ll generally be less interested in absolute values and more in tracking changes (“am I loosing or gaining weight”) and these scales would be perfectly suitable for this purpose. Nevertheless, I was a bit surprised that Fitbit and Withings didn’t use the location I had entered during account creation to adjust the scale for the local gravity acceleration. This would most likely have improved their accuracy.

Overall, the results are very good. As far as I can tell from this test, you’re not just paying for the “smart” features, you get accurate scales, too.

Further information / where to buy:


  • Some links above are affiliate links.
  • My company used to sell A&D’s UC-324NFC in our German scales shop, but we don’t anymore. The Withings WS-30 and Fitbit Aria were purchased at retail prices, A&D’s UC-324NFC was purchased with a dealer discount.

*Meaning of accuracy and precision (as used in this article):
Accuracy and precision explained

New Scales and Balances coming in 2014


A&D has confirmed that the SJ-WP series of compact bench scales is going on sale in Europe in the first quarter of 2014.

A&D SJ-30KWP Food Scale

To understand what’s so ingenious about this scale, you should know that until now, compact scales were either fast or they had a high degree of ingress protection. It was not possible to have both a very short stabilization time (<1s) and resistance to dust and liquids in a compact instrument. The reason for this is that the air pressure inside the housing of the scale changes when a load is applied (or removed). For accurate measurements, the air pressure inside and outside has to be equalized. Of course, this could be achieved by simply building a few holes into the housing, but then you would allow dust and liquids to enter. The conventional solution has been to use selectively permeable membranes which let air through and block water. However, air diffusion through these membranes takes time, slowing down the measurement process.

A&D’s new approach is remarkably simple and effective: By mounting the load cell outside of the housing, the SJ-WP scale achieves a stabilization time of 0.5s or less in combination with IP67 protection (dust tight and water proof up to 1m):

A&D SJ-WP externally mounted load cell

Fast, compact, resistant to harsh environments and easy to clean, A&D’s SJ-WP could be a game changer in the food industry.

You can already find further information on A&D’s website.

Adam Equipment

While I have no information on new products coming in 2014 yet, I was told that Adam is planning to add USB host functionality to a number of balances. This would allow weighing data to be written directly on a memory stick, greatly simplifying data logging and data transfer to a computer. This functionality is already available on Adam’s PMB moisture analyzer:

PMB Moisture Analyser


The first pages of the 2014 catalog show Kern’s continued focus on touchscreen scales. The new models include analytical and precision balances as well as platform scales. While Kern does not indicate who the ODM is, I’m pretty sure these devices are made by Radwag in Poland.

Kern Touchscreen Scales

A cooperation between the two companies would make sense: Kern’s strengths are sales and marketing, while Radwag is good at actually developing and manufacturing weighing instruments.

Further information will soon be available on Kern’s website.


The new Valor 2000 and 4000 are aimed at the food industry and are meant to improve productivity even in harsh environments. There are still some inconsistencies in the available documents but it appears that Ohaus is claiming a stabilization time of 0.5s with an IPX8 rating (no dust ingress protection; protected against submersion beyond 1m).

Ohaus Valor 4000 XW

If you’ve read this post from the very beginning, you might be wondering how Ohaus has been able to achieve this with a load cell that’s placed inside the housing. The answer is called “Flow-Through Design” and simply means that there are indeed some holes in the housing which allow air and liquids to enter and exit relatively unhindered. The electronic components are silicon sealed to protect them from fluids and condensation:

Ohaus Valor 4000 flow through design

I’m looking forward to comparing this approach with A&D’s external load cell solution.

Update March 2014: Ohaus has released a video featuring the new scales:

Smartlux (my company)

I want to take this opportunity to announce that our RS-232 communication software “232key” is going to be released this year:

Rs232 Software

Our software is designed to make it easier to transfer measurement values from any instrument with an RS-232 interface to any application which accepts keyboard input. It receives data from a scale, balance or other device via RS-232 (COM port), extracts the numeric value, formats it and “types” it into another program (“keyboard wedge”-functionality). I’ll announce the release on this blog.

A look inside the HC-i counting scale

One of the interesting features of A&D’s HC-i counting scale is its modular construction. The indicator can be separated from the base:
A&D HC-i counting scale

The following image lets you have a look inside the base of the scale. You can click on the tabs to highlight different elements and read a short description:

HC-i counting scale inside base
HC-i load cellThe load cell is attached to the bottom plate on one end and to the top plate on the other. It will slightly bend when a load is applied.
Strain gagesThe deformation of the load cell is measured by tiny sensors called strain gauges. If you look closely (or click on the image to see it in full size), you can see two of them on top of the load cell while two more are located on the bottom side.
Overload stopsThe overload stops prevent the load cell form deforming too far when a load beyond its capacity is applied. The two screws on the top are used to slightly tilt the top plate in order to adjust the overload gap between the plate and the 4 corner stops.

Please don’t hesitate to leave a comment and let me know if you’d like to see more interactive images.