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Datasheets and User Guides

App Notes

Software & Driver


1.1 - Control Panel Application (LJControlPanel)

The application LJControlPanel is included with the Windows installation package.

The LabJack Control Panel application (LJCP) handles configuration and testing of the UD series hardware (U3, U6 and UE9). Click on the “Find Devices” button to search for connected devices.

Figure 1-1. LJControlPanel Main Window

Figure 1-1 shows the results from a typical search. The application found two devices. The USB connection for a U3 has been selected in Figure 1-1, bringing up the configuration window on the right side.

  • Refresh: Reload the window using values read from the device.
  • Write Values: Write the Local ID from the window to the device.
  • Config Defaults: Opens the window shown in Figure 1-2.
  • Reset: Click to reset the selected device.
  • Test: Opens the window shown in Figure 1-3.

Config Defaults:

This option provides control over the condition of the device at power-up or reset.  Figure 1-2 shows a U3-HV with the factory default power-up configuration, which means AIN0-AIN3 set to analog input, FIO4 to CIO3 set to digital input, analog outputs set to minimum voltage (near 0), and timers/counters/watchdog disabled.

Figure 1-2. LJControlPanel U3 Configure Defaults Window
  • Write Factory Values: Clicking this will set everything back to the factory defaults and write those factory defaults to nonvolatile memory.
  • Write Values:  Change any desired settings, and then click this to write the new settings to nonvolatile memory.


Test Panel:

Figure 1-3 shows the test window for a U3 device. This window continuously (once per second) writes to and reads from the selected LabJack.

Figure 1-3. LJControlPanel U3 Test Window

Any configuration done on this screen is not written to nonvolatile memory.  These settings just affect the current condition of the device, not the reset/power-up condition.

When the test panel first loads it sets everything to factory default, so previous settings (or reset/power-up settings) will not be shown.


LJCP Settings:

Selecting Options=>Settings from the main LJControlPanel menu brings up the window shown in Figure 1-4. This window allows some features to of the LJControlPanel application to be customized.

Figure 1-4. LJControlPanel Settings Window

Search for USB devices: If selected, LJControlPanel will include USB when searching for devices.
Search for Ethernet devices using UDP broadcast packet: Only applies to UE9 device.
Search for Ethernet devices using specified IP addresses: Only applies to UE9 device.


Couldnt find this IP window. is it disabled since mine is USB??

I assume you are talking about the IP addresses in the settings window. Having a USB connection will not disable the IP window, and settings can be accessed by Options->Settings in the menu or by F2 on your keyboard. The picture on the page looks old. There is now an additional setting, minor layout changes and "LabJack IP Addresses" was renamed "Device IP Addresses".

Is there any way to set the default/start-up settings programmatically?

I would like to be able to run LabView code that detects a LabJack U3 and then write my standard settings automatically. I use a fair amount of LabJacks and setting each one up using the Config Defaults manually is a bit tedious.


Yes.  There is no high-level support, but the low-level packet is documented in Section 5.2.21.  Use normal commands to get the device set up the way you want, then use the Raw Output/Input functionality to send the SetDefaults command.  The command is the same for the U3, U6, or UE9.  You send 8 bytes {0xE8, 0xF8, 0x01, 0x0E, 0xE0, 0x00, 0xBA, 0x26} and if there is no error get back 8 bytes {0x08, 0xF8, 0x01, 0x0E, 0x00, 0x00, 0x00, 0x00}.  Start with a VI such as "LJUD U3RAW Watchdog.vi" which is in the LabVIEW_LJUD archive under "U3 Raw OutIn VIs", or email [email protected] and we can send you a VI.

eric.dauth's picture



is the source to this app LJCP available? It would help in replicating some behaviors in my own application.


LabJack Support's picture

No. The source code for our LJControlPanel application is not open or public. Is there some functionality in the application you have questions about? I can provide some functionality details and possibly code snippets. LJControlPanel is written in Visual Studios and uses the C# language. We provide C# examples here:


eric.dauth's picture

No worries, I did find the API call I was looking for used in the samples.

Thank you,