Using Ohaus Defender 3000 Scales with BarTender

In this article, I’ll show you how to capture the weight (and tare weight) from an Ohaus Defender 3000 scale using BarTender while avoiding an issue that would otherwise lead to the scale showing only “Print” on its display.


This guide applies to the new generation of Ohaus Defender 3000 scales launched at the end of 2021/beginning of 2022. The picture below shows the new indicator on the right and its predecessor on the left.

Ohaus Defender 3000 indicators: Old model on the left, new one on the right.

It was created using Bartender Designer 2022 R8 and version 1.04 of the Ohaus Defender 3000 firmware. Future versions might make things easier (or more difficult, as seems to be the general trend).

Can you use existing Ohaus scales defined in BarTender?

Let’s try it out. In the menu, go to Administer > Weighing Scale Setup:

BarTender Weighing Scale Setup

If no scale has been defined yet, this will launch the Add Scale Wizard (otherwise, click on Add Scale in the windows that appears):

BarTender Add Scale Wizard

After clicking next, you’ll be able to select “Ohaus” as the manufacturer and you’ll see a number of supported models. Select “Ohaus 3000 Series” (as this sounds most similar to “Ohaus Defender 3000 series”):

BarTender Add Scale Wizard Ohaus scales

Continue by specifying the connection method. If your scale is connected via USB or RS-232, you’ll also have to choose the COM port and confirm the interface parameters (Flow Control is set to XON/XOFF by default, it doesn’t really matter):

Click next on all further steps of the wizard. After completing it, we can now test the scale. Select it and click on Properties:

In the window that opens, switch to the Connection tab, then click on Test Connection:

Bartender will start sending the “IP” (Immediate Print) command to the scale to request the weight. It does so multiple times per seconds (4 times by default). It seems to capture the net weight correctly (5.005 kg in the screenshot below):

However, there are at least two issues with this method.

1. The scale shows “Print” all the time

When the scale receives the “IP” command, not only does it reply by sending the weight, but it also shows “Print” on its display. As BarTender sends this command multiple times per second, “Print” is all that you’ll see:

My opinion: Displaying “Print” when the user presses the Print button on the scale is useful (it gives the user feedback). Displaying it when the “P” command is received can be justified by saying that the scale should behave just as if the user had pressed the physical button. However, displaying it when the scale receives “IP” does not make much sense to me. I’m hoping Ohaus will reconsider this and change it in a firmware update. Until then, you can use the solution described below.

2. You cannot use a tare weight

The second issue I found is that once you’ve used the scale’s tare function, BarTender is no longer able to capture the net weight (and it also can’t capture the tare weight):

Solution: Define a new scale that uses the MT-SICS protocol

Unlike its predecessor, the new Defender 3000 supports (some) MT-SICS commands. The MT-SICS equivalent to the “IP” (Immediate Print) command is the “SI” (send immediately) command1. Fortunately, the scale replies to this command without displaying “Print”. Moreover, it also supports the “TA” command that BarTender uses with MT-SICS Level 1 scales to request the tare weight.

Note: You can explicitly set the scale to “SICS” by going into the “Print” menu (for RS-232) or “Print1” (for USB or Ethernet) and setting “Assignment” to “SICS”, but this was not necessary in my tests.

Let’s start the Add Scale Wizard again, but this time, you don’t select an existing model. Instead, choose Define a model not listed above:

Define a new scale model

Then, select Ohaus as the manufacturer and enter a name for your new model, e.g. “Ohaus Defender 3000 SICS”. Under Protocols Supported by this Scale, select “Mettler Toledo (MT-SICS Level 1)”:

Continue with the Wizard as before.

I used this opportunity to test the optional Ethernet interface of the new Ohaus Defender 3000. I set it to acquire an IP address via DHCP (which is out of the scope of this tutorial), connected it to our network and then copied its IP address from the menu under Ethernet/IP Address. The port (which is also displayed by the scale) is alway 9761:

Specify scale connection in Bartender: TCP/IP Network Port

You can – of course – still connect to the scale using a COM port.

After completing the Add Scale Wizard, it is again time to test the connection. Click on Properties:

Installed Scales: Ohaus Defender 3000 SICS

In the new window, switch to the Connections tab and click on Test Connection:

You’ll now see that the net weight and tare weight are acquired correctly:

Ohaus Defender 3000 current weight shown in BarTender

Futhermore, the scale’s display now shows the weight instead of just “Print”.


The new Ohaus Defender 3000 scales are compatible with BarTender, but initial setup is not quite as straightforward as one might expect. You’ll get the best results by defining a new scale that uses the MT-SICS protocol (which the new Defender 3000 supports, unlike its predecessor).

I hope this tutorial is helpful. Please don’t hesitate to leave a comment, but please note that I am in no way a BarTender expert and that answering BarTender-related questions is not something I particularly enjoy. I suggest using the BarTender’s Online Help system or contacting Seagull Scientific if you need support with their software.

  1. Well actually, the equivalent would be “SIU” (send immediately in display unit), but this article is long enough and “SI” is the better choice anyway. ↩︎

Using verified Ohaus SJX scales with our software

Most class I and II weighing instruments use what is called an “auxiliary indicating device” with a “differentiated scale division”1: On the display, the final digit or digits are visually distinct from the others. This is also the case with Ohaus SJX scales that have been verified (e.g. the SJX6201M):

Note how the scale division (d) is one tenth of the verification scale division (e) when weighing in g

This digit is enclosed in square brackets when the weight is sent over one of the optional interfaces (such as RS-232, USB, or Ethernet). Example:

   1234.[5]     g

By default, our software does not capture a digit that comes after a non-numeric character. This can be easily fixed in two steps. We’ll use screenshots from Simple Data Logger as an example, but the procedure is basically the same for our 232key virtual keyboard wedge software2.

1. Change the regular expression used to capture the weight

In the Input tab, click the Customize button and replace the regular expression with the following one:


This will ensure that the opening square bracket and the last digit are also captured (shown in blue in the Event Log):

Remove the bracket

The string we’ve now captured is not a number because it contains a bracket. Writing it to a file like this would make things complicated when processing the data later.

Fortunately, you can easily remove the bracket: Go to the Process tab, check Enable Editing, and enter the opening square bracket “[” in the Remove characters field:

SDL will now properly write the complete weight as a number to the CSV file, which can be opened in Excel or other programs:

Important: If you are utilizing our software in connection with a verified scale, please ensure that such usage is compliant with the regulations and requirements of your local jurisdiction.

1: See OIML R76 (PDF) for further information
2: For an example that uses 232key, see this article

How to connect your Ohaus Valor 7000 scale to a PC and transfer the weight into any application

I’ve made a short, but comprehensive walkthrough video on connecting an Ohaus Valor 7000 scale to a PC. It uses the standard RS-232 port, a suitable data cable, an RS-232-to-USB converter and our free 232key virtual keyboard wedge software.

This will enable you to transfer the weight directly into a variety of applications as simulated keystrokes, such as Excel, a LIMS, or any other application of your choice. It even works with browser-based applications!

This guide can also be used for the very similar scales from the popular Ohaus Ranger 3000 series.

Ohaus Valor 7000 with 232key software

Video transcript


This video will show you how to connect your Ohaus Valor 7000 scale to a PC and configure the 232key Virtual Keyboard Wedge software.

Connect the RS-232 cable to the scale

To prevent accidental overloading of the scale, remove the weighing pan and pan support. Then turn the scale upside down.

Open the compartment on the bottom. Connect the serial cable and secure it with the thumb screws.

Remove the cable breakaway tab

Before closing the compartment, break the middle tab on the cover. Turn the balance back over and put the weighing pan back in its place.

Connect the USB converter to the RS232 cable

Connect the USB converter to the other end of the cable and secure it with the thumb screws.

Connect the USB converter to your PC

Plug the converter into a USB port on your PC. The driver should install automatically. If not, see the video description for download links.

After the device is recognized by Windows, a new COM port will appear. You can find this port in the Windows Device Manager under “Ports (COM & LPT)”. In our case it is called COM9, but the number will probably be different on your system.

Configuring 232key

Download and install 232key, then launch the application.

In the “Input” tab, select the new COM port.

Set the “Device” to Ohaus and press the “Set defaults” button to set the serial interface parameters.

In the “Output” tab, select your keyboard type and, if necessary, a key that should be “pressed” after the weight is entered.

Go to the “Start” tab and press the “Start” button. 232key will now start listening for incoming data on the specified COM port and output it as simulated keystrokes.

Switch to the target application, e.g. Excel or a LIMS. For testing purposes we’ll just use Notepad.

Transfer the weight

Turn the scale on. Place an object on the weighing pan and press the PRINT button.

The weight is entered into the target application.

For more information, please visit our website at