U3 Quickstart Tutorial | LabJack
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U3 Quickstart Tutorial

U3 Quickstart for Windows Overview

1. Install the appropriate LabJack driver and software bundle.
The utility application referenced in the following steps (LJControlPanel) is only available in the Windows Installer. The package for Linux and Mac will allow communication to the U3, but no similar application is available for Mac and Linux at this time.

The installer covers UD devices (U3, U6, UE9) and LJM devices (T-series, Digit), so not all installed applications will work with the U3.  The following applications work with the U3:

  • LJControlPanel,
  • LJSelfUpgrade,
  • LJLogUD, and
  • LJStreamUD.

Only run 1 application at a time.

If there is an installation problem, see the Windows Installer Troubleshooting (App Note)

2. Connect the U3 to the computer or hub.
The status LED should blink at power up and then stay solid on. If Windows asks about installing new hardware accept the defaults.
3. Run LJControlPanel.
LJControlPanel is a free application installed along with the driver. You should be able to find it in the Start Menu links.
4. Click "Find Devices".
5. Select the connection (i.e. "USB - 1").
The right hand side of the screen will change.
6. Click "Test".
 This brings up the test panel where you can read all inputs and write all outputs. This test panel is a great tool to use often and lets you check out basic hardware operation before trying more complex software.
7. Connect jumper wire from DAC0 to AIN0/FIO0.

DAC stands for "Digital to Analog Converter", AIN stands for "Analog Input", FIO stands for "Flexible I/O". On the U3, Flexible I/O lines can be configured as either analog inputs, or digital I/O.

For a guaranteed valid connection, a conductor must be clamped in the screw-terminal, not just touching some part of the screw-terminal.

8. Control Panel will read the voltage level of AIN0.
Adjust the DAC0 analog output voltage, you will see AIN0 follow DAC0 if the jumper wire is secured.
9. Connect one end of the jumper wire to GND, touching the other end inside the FIO4 terminal.
GND stands for Ground. Try connecting and disconnecting the FIO4 end of the jumper wire.
10. Control Panel will read the digital input as changing.
The FIO4 checkbox will change from selected to unselected showing that there is a voltage change.

Moving forward from here...

Basic Functionality Examples:

Software Options:

See the U3 Software Options.

Getting Support:





SPI stands for Serial Peripheral Interface.  See Section 4.3.10 of the U3 User's Guide.  The link you sent says "Data Output: Yes", but they will have to tell us how the data is output.

Also see our Range and Depth Sensors app note.

Good morning

       We purchased your U3-HV. I installed the driver software and I believe everything is OK. When I try to run your example program (LJM_VBA_efunctions) I get an compile error message (can't find project or library). The high lighted part of the program is in the sub ErrorMessage     Str$. I went through the object browser and I think everything is OK. I have done a little program in the past but consider myself a newbie with a lot to learn. I am using the U3-HV to record voltage (0-10 volts) from an encoder. Then I will format it to degrees (0-360) so I can take readings from an HP analyzer every 5-degrees. Thank you in advance for any help.


In an email you mention you are using Excel 2010. Make sure to add the LabJackUD_VB.bas file to your spreadsheet's VBA project so it can find the UD driver functions. Also, take a look at the U3\VBA_U3\ljud_vba_u3_simple.xls Excel example in the UD Visual Basic examples download to help get you started in Excel:


The LJM_VBA_efunctions example is an LJM driver example. The LJM Visual Basic Excel example and the LJM driver in general does not support the UD series devices (UE9/U3/U6) or the U12. Download and install the UD driver from this page and use the UD Visual Basic examples I linked to previously for a U3 Excel example.


i am new to labjack

i want to measure 8 thermocouples readings in labview

and i also want two analog outputs that i can control with labview

which Labjack product fulfill my requirement ,  is U3 H is good for this ?

See the Thermocouple App Note for general information.  Make sure you avoid complication #5 if at all possible.

To acquire 8 thermocouple signals with the U3, you would need 4 LJTick-Amps, but that would cost more than a U6.  The best solution for 8 thermocouples is something from the U6/T7 families.  The least expensive option would be a U6 with CB37, and I would also recommend an LM34CAZ (digikey.com) for CJC.

ok with U6/T7 we will required just one CB37 ?

and ADC module is built in this system ?

Yes, the U6/T7 and one CB37 setup will be able to acquire data from up to 14 thermocouples and output 2 analog signals.  We recommend the T7 over the U6 for thermocouple readings as it has built in CJC conversion features.


i still have a confusion about T seriese

as i have to measure 8 thermocouples which have double ended wires

so i think there will be need of 8 differential inputs or 16 analog inputs but T7 " have 14 analog inputs which are enough for 7 thermocouples not for 8 i think..... kindly guide me

Do you mean that the thermocouples have 2 wires?  Usually you connect the + to AINx and the - to GND.  See related discussion in the Thermocouple App Note, and make sure you avoid complication #5 from that app note.  If you need more help, I suggest you continue this discussion on our forum rather than here on the U3 Support Homepage.

Hi, I am new to Labjack. We heard that your U3 machine can help measure video streaming latency and lip syn, but when I see the features, I can' t tell those functions. Could you help me on that?

Thank you

The LabJack U3 is a USB based data acquisition and control device that is great for acquiring analog & digital values at various rates.  Depending on how your system is set up a U3 can likely help but it will probably require some electrical circuitry to do so.  The U3 doesn't have any direct abilities to stream video or detect lip syn unless you can convert those metrics to analog or digital voltages that can be sampled and further analyzed on a PC.

I recently purchased a U3 HV to interface alarm signals from a generator to a PC. Which is the best way of getting alarm signals from U3 software out to other PC,s or phones so I know when generator has problem from a remote location?.

I would suggest running some software on the local PC that sends email/sms when your event is detected.  The programming options above that should all have that capability, or post on AzeoTech's forum to see what they say about doing that through DAQFactory (and perhaps also DAQConnect).


I am carrying out a college project in which i have to measure the displacement using sensors and display them using PC. I've decided to go ahead with LABJACK U3 ADC module and LABVIEW software. The problem is I am in a fix as to how/wat type of sensor should I use for measuring. What should be the output of the sensor and to which port of LABJACK U3 should I connect. It would be really helpful If u could tell me as to technical specification of the displacement sensor that i should buy. My mail id - [email protected]


Thanks & regards.

Hi, i am planning to buy a U3HV and read an encoder signal which has 3600 pulses per circle, decode and display in matlab. I am not sure, is U3 HV able to read the signal from this encoder? the vlotage is 5V.  thanks in advance.

I bought a LabJack U3-LV and downloaded and installed the software. It immediately crashed with a Common Run Time Library Error  80004005 the program will now terminate. I have submitted a support question and have not heard anything for two days. Not a good start.

Sorry but I searched our support box (including spam trap) using your name and also domain, but don't find anything except a couple emails from last night.

In your email you mentioned that the crash was from LJControlPanel.  I have never heard about that type of crash, so someone else will have to follow up later today.

The error could be related to your .NET installation which LJControlPanel uses. Try running LJSelfUpgrade and see if you run into this error as it also uses .NET.

As for resolving the issue, try installing .NET from the download here (if it is already installed, choose the repair option):


If that doesn't resolve the issue, please provide a screenshot of the error message and send it to [email protected] .

I was used the labjack U3-HV and it was worked properly, now I want to use it with the same program but there are an errors appear in the statement "  dblDriverVersion = GetDriverVersion() " the error is ( compile error sub or function not defined) please advice......

Hey there LabJack,

I'm running Windows 8.1 and attempted to install the most recent drivers from the installation utility. The file was labeled 'LabJack-2015-02-02', and the driver's date is 12/15/2014, version

The driver isn't digitally signed, so Windows was having a fit with the installation.  I had to boot Windows with signed driver verification disabled in order to install it correctly.

Just thought I would let you know.

Hi Nathan,

Thanks for your comment. We are in the process of fixing this issue.

Thanks also for your patience!


I am reading features of U3-LV.

In features section, 'The first 8 flexible I/O lines (FIO0-FIO7) appear on built-in screw terminals. The other 8 flexible I/O lines (EIO0-EIO7) are available on the DB15 connector.'

But If I see image of U3-LV, I see from FI04 to FI07 only.

Where are first four ports?



When we connect our LabJack U3-HV to the computer through an USB port and open the LJControlPanel. The LJControlPanel detects the device, but when we try to write values the button won’t work. Also none of the other programs detect the device, Kipling says no devices were found and other programs give back errors like:





LabVIEW ERROR #1007 Error 1007 occurred at OpenAny

Keep in mind that the U3 is a UD device.  Kipling is for LJM devices (T7), and your "LJM" errors also suggest programs talking to the LJM library.


I installed labjack newversion software for U3-LV. My test panel is showing analogue voltage data into any ADC channel. But I cannot see the graphs using LJSTREAMUD. When I click on start stream, it says

LabVIEW Error #1007:  Error 1007 occurred at OpenAny. Please help me. Thank you.


That error means that LJStreamUD could not find any available UD devices (U3, U6, UE9).  The most likely problem is that your U3 is not available because some other program (e.g. LJControlPanel) has it open.