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Datasheets and User Guides

App Notes

Software & Driver


LJControlPanel - Windows Only

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.


It would be nice if the control panel would also work with the 64bit driver.

There shouldn't be any issues with LJControlPanel and installing the 64-bit driver.

LJControlPanel is a 32-bit application, and runs fine on 64-bit systems using the 32-bit driver (LabJackUD.dll, the low level driver is 64-bit but that should work fine as well).  If it is not working for you then there could be another issue.  If you email us at [email protected] and let us know how it is not working we can likely help you figure it out.

For some reason when I click "Find Devices (F3)" in LJControPanel, a new branch in the device tree appears

-Already Open


         |_> 1 U3

I can't do anything beyond that!

It worked before I updated the firmware.

That seems to suggest that some other software has the U3 open.  If you can't find any suspect software to close, try rebooting your PC.

I have installed the latest build on both windows XP and 7 machines and find that the logging applications don't work.

They start by asking for a directory, but the selection pane is transparent and the mouse click acts on the app behind. I have to drag the pane to open desktop to select.

When I have selected a working directory the app immediately responds with error 56 and freezes.

I have tried this with UE9 connected by USB and ethernet, the test app works and finds it through both interfaces.

I have successfully updated the UE9 firmware.

Please what could possibly be wrong?

49.99 MB
2014-10-14 11:45

This the LJControlPanel page.  Sounds like you are saying that LJCP works fine, but perhaps LJLogUD and LJStreamUD are both giving the problems you describe?

Yes right, I'm on the wrong page. As ever.

Correct, LJLogUD and LJStreamUD are the problems.

I used the current installer which you referenced (2014-10-14) which gives me UD V3.45 (from main screen of LJControlPanel) and LJLogUD V1.18.  My machine is Windows 7.

1.  Transparent Working Directory Selection Window:  I'm not seeing this, and have not heard of this behavior before.  Perhaps related to some Windows setting?  If you click "Change Working Directory" in LJLogUD do you see this every time?

2.  Error 56:  Not sure on this either, but sounds like a LabVIEW TCP error.  Try connecting the UE9 by USB only and make sure all other related software (e.g. LJControlPanel) is closed.  Also, before running LJLogUD, find LJlogUD.cfg and LJlogUD_open.cfg (should be the working directory you have chosen) and delete them, which will put LJLogUD back to default conditions.

Note that with the UE9, when LJLogUD opens in the default condition you will get an invalid range error because the range on every channel is set to +/-10V, but +/-5V is the max range available on the UE9.