The LabJack data acquisition modules are flexible I/O modules for getting signals in to and out from your computer. The family features wide software support with drivers and code examples for a range of platforms and languages. The U12 was the first LabJack modules released and is very straight-forward to use. Many existing examples and much of the documentation is based on the U12.
The LabJack modules come with Windows software that allows you to be quickly up and logging and graphing data.
The LabJack U12 has 8 screw terminals for analog input signals (AI0-AI7). These can be configured individually as 8 single-ended channels, 4 differential channels, or combinations in between. Each input has a ±10 volt input range, 12-bit resolution, and an input bias current of ±90 microamps. Differential channels can make use of the low noise precision PGA to provide gains up to 20.
The LabJack U12 is capable of both software and hardware timed acquisition. When using software timed acquisition (also called command/response), the PC sends a command to the LabJack, and it responds with data. This mode can acquire 4 channels at up to 50 samples/second per channel, or 8 channels at up to 25 samples/second per channel. When using hardware timed acquisition, the PC sends a command to the LabJack telling it to start a burst or stream mode acquisition. Both burst and stream mode take advantage of the LabJack's precision timing crystal and high-speed sample buffer. In burst mode, up to 4,096 samples will be acquired from 1-4 channels at up to 8,192 samples/second and stored in the buffer. After the acquisition is complete, the data is transferred to the PC. A hardware trigger can be configured for burst mode that starts the acquisition when a digital input changes state. In stream mode, data is acquired from 1-4 channels at up to 1,200 samples/second and stored in the LabJack buffer. Simultaneously, the data is transferred from the LabJack buffer to the PC buffer, allowing the data to be streamed to disk continuously. Click here for more info on data rates.
The LabJack U12 has 2 screw terminals for analog output signals (AO0 & AO1). Each analog output can be set to a voltage between 0 and the supply voltage (+5 volts nominal) with 10-bits of resolution. The analog outputs are controlled in command/response mode at up to 50 Hz per channel.
The LabJack U12 has 20 digital I/O channels which can be individually configured as input or output.
Connections to 4 of the digital I/O are made with the built-in screw terminals (IO0-IO3). These 4 channels have built-in over voltage/short-circuit protection. As inputs or outputs, they are controlled/read in command/response mode at up to 50 Hz per bit. As inputs only, they can be read with the high-speed burst and stream modes.
The remaining 16 digital I/O are accessed through the DB-25 connector and controlled/read in command/response mode at up to 50 Hz per bit. These channels can sink or source up to 25 mA each (total sink or source current of 200 mA max for all 16), allowing direct interface to many relays.
There is one 32-bit counter available on the LabJack U12 (screw terminal CNT), capable of counting frequencies up to 1 MHz. The counter is read in command/response mode at up to 50 Hz or up to 300 Hz in hardware timed stream mode.
Watchdog Timer Function for Unattended Operation:
The LabJack U12 also has a watchdog timer function available which can change the states of digital I/O if the LabJack does not successfully communicate with the PC within a specified timeout period. This function could be used to reboot the PC allowing for reliable unattended operation.
Portable Data Acquisition and Control:
When used with a notebook PC, the LabJack U12 becomes a convenient portable data acquisition and control system. The watchdog timer function allows the development of a system which has the reliability of a data logger with the power of a PC. The low-power design of the LabJack U12 allows it to draw all it's power from the USB port. Also, no UPS is needed when using a LabJack U12 with a notebook PC. In the event of power loss, both the LabJack and the notebook will continue to operate.
High Channel Count Applications:
By using USB hubs, up to 80 LabJacks can be connected to a single USB host, providing an inexpensive solution for low-speed high channel count applications.
Free Example Application Software:
Includes various example applications, including LJlogger and LJscope. LJlogger provides data logger type functionality. It reads all inputs, controls all outputs, writes real time data to disk, and sends email when events are triggered. LJscope is a simple virtual oscilloscope program. This software is free and can be downloaded from the U12 Support page for evaluation.
Free Driver Software:
Drivers are provided as a DLL which can be called from most programming languages. Also included are an ActiveX wrapper and LabVIEW VIs which call all the functions in the DLL. Most driver functions have a demo input, so applications can be developed and tested without hardware.
Drivers and Examples:
The U12 Support Page has drivers and sample code. LabJack have drivers for the three major operating systems, and examples for most common programming languages.
This product comparison shows the different Labjack models and their features.