LabJackDAQ

LabJackDAQ

USB DAQ device

The LabJack U3-HV is a versatile DAQ device that is easy on the wallet/purse. It allows for visualization and recording of four analog inputs (12-bit, 50 ksamples/s, ±10V), two analog outputs (5V, 10-bits of resolution, 16 Hz), and up to twenty digital I/O (5V input, 3.3V output, and reads/writes 0.6-4.0 ms).

The documentation for LabJack is extensive, but we have a couple of pointers to get researchers going quickly; and special consideration for the typical neuro-researcher is given, providing a very cost effective solution to a lot of needs. We offer tips to get up and running quickly with the software, provide housing to protect the system and attach basic BNC Connectors, and show how to implement full 5V input and output of digital signals; all standards of biological research.

Further explanation can be found through our LabJack Example write up.


BNC Connectors

The U3-HV comes in either bare board or standard (with handy screw terminals) format. These are great, but researchers often use BNC Connectors and cables for their TTL signals. These outdated and bulky connectors are heavy, so simply going from bare wire to BNC Connectors creates all kinds of headaches. To solve this problem, we have created an FDM print to easily attach up to 8 BNC Connectors, and up to 12 smaller wires. The design files can be found here, and the STL files for printing and viewing the part can be found here. Both the bare board and the standard system can be used with this design: Simply unscrew the four screws on the underside of the LabJack, place the LabJack in the enclosure, and screw the screws back in.

We used 50 Ohm straight bulkhead BNC Connectors, such as the Amphenol B6651B1-NNYL3G-50.

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5V Output

The U3-HV can accept and read 5V inputs without issue (Pulse Width Modulation (PWM) at 5V is Transistor to Transistor (TTL) logic often used by researchers). In fact, the system is able to handle up to 10V. However, the U3-HV outputs its digital signals at 3.3V, not 5V. A simple Bi-Directional Logic Level Converter from SparkFun allows for easily sending a 3.3V signal out of the LabJack and bumping it up to the necessary 5V for the rest of your experimental setup. This can run over four channels. The wiring is simple. Tie all grounds together (to do so is safe and reasonable, but sloppy. Just don’t tell my EE Professor!). Then you can use four channels on the ‘high’ (5V) side that correspond to the ‘low’ (3.3V) on the other side.

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The final piece to consider is that you need to tell the logic converter what is high and what is low: Constant 5V and 3.3V. This is done with the HV and LV pins. The LabJack outputs a 5V high (HV) signal on its VS pin. However, it does not have a constant 3.3V pin. In order to achieve this, we will tell the LabJack to turn on a pin as high immediately when powered on. To do this (MS Windows only), click Start => Labjack => LabJack Control Panel. Click on your device (USB -1) and then ‘Config. Defaults’. Change the digital state of Pin 07 to ‘Output High’ and click ‘Write Values’.

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Side note: Setting a DIO to input will make the pin appear high at 3.3V at start-up, but this is only because of a weak pull up resistor.


Software

Download the software for your OS here. Currently, only MS Windows is supported for the easiest (and quickest) implementation of the C++ software that we will discuss here. Connect the LabJack and then go to Start => LabJack => LabjackStreamUD

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Note that to exit the software, click the red Exit button (there is no typical Windows exit). Keep the number of channels to four, set the scan rate to 2500, update the data prefix to “Neuropixel Camera Sync (Today’s Date)”, change the working directory, and set the maximum file size to near 5 MB (5242880 Bytes). When ready, start the stream. The data is saved as a .dat. There are many ways to view/plot/manipulate the data, including just renaming the file as .cvs and opening with a spreadsheet viewer (MS Excel), but man, that’s lazy. My kind of lazy. :)


ONE Core acknowledgment

Please acknowledge the ONE Core facility in your publications. An appropriate wording would be:

“The Optogenetics and Neural Engineering (ONE) Core at the University of Colorado School of Medicine provided engineering support for this research. The ONE Core is part of the NeuroTechnology Center, funded in part by the School of Medicine and by the National Institute of Neurological Disorders and Stroke of the National Institutes of Health under award number P30NS048154.”