Can I use my scale or balance with 232key?

Our free software 232key enables you to easily transfer the weight from your scale or balance to any application running on your PC (as simulated keystrokes). It contains a list of compatible devices that we are constantly expanding.

However, we cannot possibly test every scale or balance on the market. Using a practical example, this blog post will show you how to determine whether your balance is compatible with our software.

232key requirements

As of version 2018.1.0, the following requirements can be found on our 232key homepage (under “limitations”):

  • Data sent by your device has to be in ASCII format.
  • Your device has to send each line of data only once, not continuously (by pressing a key on the device or automatically).

These requirements may change in future version. We recommend that you always consult our 232key.com website first.

Step 1: Prerequisites

Scale or balance

You’ll need your scale, of course. For this example we used an Excell FD130 scale which we found among our samples:

Excell FD130 scale

At the time of the writing of this post, this scale did not have predefined device profile in 232key.

User manual

It’s a good idea to try to find or download the user manual for your scale. As you’ll see below, you’ll most likely need it.

Interface

Your scale must be equipped with an interface which can be connected to a COM port on your PC (or appears as a COM port when connected). The FD130 has a DB25F port:

Serial DB25F interface (RS-232)

Cables and converters

We used a straight (1:1) DB25M to DE9F RS-232 cable with an FTDI US232R-10 converter plugged into a USB port on our PC:

Scale connected to PC with RS-232 to USB converter

Your scale will probably require a different cable. If you’re lucky, the user manual contains further information. We’ll address the topic of finding the right serial cable in an upcoming post (it can be quite complicated).

Caution: Some scales use interfaces for other things than transferring data (e.g. for relay outputs or as a way to supply power to peripherals). Connecting such a scale to your PC with an incompatible cable could damage both devices.

Serial terminal program

We used HTerm, which you can download here. Simply unzip the downloaded file and start HTerm.exe (no installation required). There are many other (free) terminal programs which you could also use.

Step 2: Transfer the weight to a terminal program

Before using an unlisted device with 232key, it’s a good idea to get it to work with a terminal program. Just like 232key, a terminal program requires that you make a few settings before connecting to your scale:

HTerm interface parameters

  • COM port
  • Baud rate
  • Data bits
  • Stop bits
  • Parity

Only one COM port was shown on PC (created when the FTDI converter was plugged in). If you have the choice between multiple ports, consult the Windows Device Manager to determine the correct one.

We found the following interface parameters in the user manual of our FD130 scale:

  • 1200, 2400, 4800 or 9600 baud (no default value was specified)
  • 8 data bits
  • 1 stop bit
  • No parity

To determine the correct baud rate, we accessed the scale’s RS-232 configuration (we couldn’t have done this without the user manual):

Scale set to 9600 baud

After all settings were made, we pressed the “Connect” button in HTerm and immediately saw a lot of data coming from the scale:

Data from scale shown in HTerm

The data contained a stability and net weight indication, a polarity sign, the weight and the unit, then a carriage return and finally a line feed character:

ST,NT,+     0g\r\n

Setting “Newline at” to “LF” in HTerm made things a bit clearer:

Data from scale shown in HTERM

Concerning the requirements mentioned above, we confirmed that the data was sent in ASCII format. However, the scale was continuously sending 4 values per second, which is not suitable for use with 232key (as all these values would be typed).

We again consulted the manual and found that the setting could be changed from “rnP 2 – continuous transmission” to “rnP 4 – press the ⏎ key to transmit”.  As the description says, in this mode the user has to press the ⏎ key on the scale to send the weight to the connected PC (once).

Another mode suitable for use with 232key was “rnP 1 – stable transmission”. In this mode, the scale sent each (stable) weight once. This is often referred to as “auto print on stability”.

Your scale may or may not have several different transmission modes. Please refer to your manual for further information. Unfortunately, there are some scales which only support continuous transmission and are therefore not suitable for use with 232key (at this time).

Tip: Check whether your balance has a print button. If so, it can probably be used with 232key.

Troubleshooting

No output at all

Unfortunately, there can be many reasons. Please read our extensive troubleshooting section on 232key.com.

No readable output

If the output in the terminal program contains no human readable data, you’ll have to fix this before trying to use the scale with 232key. As an example, setting the baud rate in HTerm to a wrong value (e.g. 4800) resulted in the following output (with “Show errors” selected):

Wrong baud rate

If you’ve confirmed that all interface parameters in HTerm match those of your scale and still can’t read the output, the scale might not be sending data using the ASCII format. If no ASCII mode is available, it cannot be used with 232key.

Other values than the weight

Instead of sending only the weight as shown on the display, some scales send a lot of data to the connected PC. Below you can see the output when we set our scale to a ticket format meant to be used with a printer (“rnP 6”):

Scale ticket format

If the data sent by your scale contains numbers other than the weight, they will also be captured and typed by 232key. This is usually not what you want.

There are two ways you can try to fix this:

  1. Configure the scale. Refer to the manual to find out if it’s possible to change the output format to a more simple one that sends only the weight.
  2. If the line with the weight can be reliably identified (because it starts with or contains certain characters), you can use a custom regular expression in 232key Plus to capture the weight and ignore all other numbers.

Step 3: Use the scale with 232key

As we were able to read the output in HTerm and had fixed the continuous transmission issue, we proceeded to configure 232key for use with our Excell FD130 scale:Input tab in 232key with COM port and interface parametersWe selected “generic measuring instrument” as the device and set the COM port and all interface parameters to the same values as in HTerm. As the terminator, we selected “LF”, the last character in each line of data sent by the scale (as seen above).

In the output tab, we instructed 232key to send an enter key after typing the weight (this is of course up to you and your application).

We then pressed the start button and switched to Word for testing purposes. By pressing the ⏎ key on the scale, the weight was typed by 232key:

Weight from scale shown in Microsoft Word

Received data and captured/typed values could also be seen in the event log in 232key:

232key event log with data form FD130 scale

Further information and support

Please visit 232key.com to download our free software for scales and balances. Our website also contains an extensive documentation, FAQ and troubleshooting section.

Should you have any questions, please post them in our support forum. However, please keep in mind that the problem is not caused by 232key if you cannot see readable output in a terminal software.

We regularly publish blog posts with application examples. You can find all 232key posts here.

If a virtual keyboard wedge software like 232key is not what you need, please have a look at our other programs.

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