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Enumeration is the process where the PC’s operating system gathers information from a USB 
device that describes it and it’s capabilities.  The low-level drivers for the LabJack U12 come 
with Windows and enumeration will proceed automatically.  The first time a device is 
enumerated on a particular PC, it can take a minute or two, and Windows might prompt you 
about installing drivers.  Accept all the defaults at the Windows prompts, and reboot the PC if 
asked to do so.  The Windows Installation CD might also be needed at this point.  Make sure a 
CD with the correct version of Windows is provided.  Enumeration occurs whenever the USB 
cable is connected, and only takes a few seconds after the first time. 
 
When enumeration is complete, the LED will blink twice and remain on.  This means Windows 
has enumerated the LabJack properly.   
 
If the LabJack fails to enumerate: 

• 

Make sure you are running Windows OS version 4.10.2222 or higher, 

• 

If Win98SE, check out win98sehid.zip from our downloads page, 

• 

Try connecting the LabJack to another PC, 

• 

Try connecting a different USB device to the PC, 

• 

Check our online forum and/or contact LabJack. 

Software Installation 

Although, the low-level USB drivers for the LabJack are included with Windows, high-level 
drivers are needed to send and receive data.  The included LabJack CD installs the high-level 
drivers, example source code, and example applications. 
 
Close all open applications, especially LabJack related software, and insert the LabJack CD.  If 
autorun is enabled, the installation program should start automatically.  If the installation does 
not start, you will have to manually double-click on LabJackVXXX.exe. 
 
When the LabJack installation is finished, it will start the National Instruments LabVIEW Run-
Time Engine (LVRTE) setup.  The LVRTE is required for the example applications, such as 
LJtest.  If prompted to reboot after this installation, go ahead and do so.  Virus scanners can 
often interfere with the installation of the LVRTE.  If you have trouble running the example 
applications, repeat the LabJack software installation to make sure the LVRTE is installed. 
 
To test the installation, start LJtest by selecting 
 

Start => Programs => LabJack => LJtest.

 

 
Make sure “Test Fixture Installed” and “Continuous” are not selected, and press the “Run” 
button.  LJtest should step through and pass 8 separate tests.   

Hardware Description 

The external features of the LabJack U12 are: 

• 

USB connector 

• 

DB25 digital I/O connector (D lines) 

• 

Status LED 

• 

30 screw terminals. 

 
The USB connection provides power and communication.  No external power supply is needed.  
The +5 volt connections available at various locations are outputs, do not connect a power 
supply. 

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