Tag: RS-232

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

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

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 parsed, 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. Ideally, the weight should be the first numeric value sent and it should only be sent once (after you’ve pressed a key on the scale or on stability), not continuously.

The vast majority of scales and balances available on the market today fulfill these requirements. To give you a few examples, you should be able to use 232key with most or all scales and balances made by A&D, Mettler-Toledo, Ohaus, Sartorius 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 Set defaults to load the settings.
interface settings for weighing scales and other instruments

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

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.
output weight with dot or comma

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 Output tab.
Press Enter after weight

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. There you’ll also find the documentation, an extensive troubleshooting guide and FAQ. Should you still have questions or feature suggestions, please post them in our support forum or as a comment below.

Do you prefer to write the weight to a file instead?

232key is a great solution for sending the weight from your scale to an application running on your PC (as simulated keystrokes). In some cases, however, it makes more sense to record the weight to a file which is opened later (e.g. in Excel).

This is particularly true for unattended data logging applications running over long periods of time. Another example are applications with high data rates (several weight values per second) which would overwhelm your PC when sent as keyboard inputs.

For these use cases, we’ve created Simple Data Logger, an easy to use solution for recording the weight sent from your scale to a CSV file. You can read more about it on this blog or on www.smartlux.com/sdl.

Article last changed on November 19, 2020: Screenshots and some links updated.

RS-232 troubleshooting: fake chips

RS-232 is still the most popular interface for balances and scales. It is often described as “simple”, however, when things don’t work as expected, finding the cause can be difficult.

This article does not aim to be a comprehensive RS-232 troubleshooting guide (for this purpose, please refer to this PDF document from Agilent Technologies or the troubleshooting section on our 232key website). Instead, it is supposed to raise awareness of an issue that is often ignored: counterfeit ICs.

When you’ve tried everything and still can’t reliably communicate with your scale via RS-232, there’s a chance a fake chip may be the cause.

Just a few weeks ago, the thought of encountering counterfeit ICs in digital scales had not crossed my mind. Thanks to FTDI’s recent attempt to “brick” counterfeits via Windows Update, fake chips are now a hot topic on the web. While I don’t agree with the way FTDI tried to punish the end user, I wish the controversy had occurred a few weeks earlier. This would have saved me a lot of time.

Back then I was doing the final QC for several scales which were about to be shipped to a customer. The last item on my checklist was “bidirectional communication using RS-232”, something I had done many times before with this exact model. What should have taken a few minutes ended up taking me several days and nearly drove me crazy because the problems I encountered were difficult to replicate. Eventually, I arrived at the conclusion that something was very wrong with the MAX232CPE+ chips, which are responsible for converting TTL signals to RS-232 levels. After doing some research on the internet*, I started to suspect those chips were counterfeit. It seemed like a far-fetched idea** at the time, but I still desoldered them, took a few pictures and sent them to Maxim Integrated.

Fake MAX232CPE+ and MAX232EPE+

Counterfeit MAX232CPE+
Fake, fake and fake.

Thankfully, I received a reply in less than two hours:

“Yes these parts are counterfeit, they do not match markings of lots we manufactured.”

Now extremely suspicious of all MAX232s***, I disassembled a few more scales from 4 different vendors. 3 contained ICs belonging to the MAX232 family, so I sent the pictures to Maxim Integrated, too. In addition to the chips used by the scale manufacturer which had prompted me to start this investigation, one chip used by another manufacturer was also flagged as counterfeit.

Counterfeit MAX232EPE+
Counterfeit MAX232EPE+

To be fair, my sample size is too small to draw meaningful conclusions regarding the entire weighing industry. However, if you’re in the business of making weighing instruments and were blissfully unaware of this issue, I hope this article serves as a wake-up call.

* I found documents like this one (16 MB PDF presentation by SMT Corporation) or this one (100 KB PDF, University of Conneticut), this article by Maxim Integrated and even videos of YouTubers walking through huge electronic component malls in Shenzhen where almost everything is counterfeit.

** Though not quite as far-fetched as the manufacturer’s idea that “static build up from the polystyrene packaging in road transportation” was to blame.

*** And also seriously angry at having wasted so much time doing something the manufacturer should have done. I won’t do any naming and shaming here, though.

Update October 3, 2017: Several articles concerning this issue have appeared since I originally wrote this blog post.

Update October 15, 2020:

Update February 13, 2022: