The U12 series is the original LabJack. The device is solid - the firmware hasn't changed in a decade, and it has a very long service record of reliability and customer satisfaction - all with an attractive price point. It can be used for measurement and control within simple analog and digital systems. We continue to produce and sell U12s because a large number of our customers have integrated them successfully into other products.
New applications should consider the U3 series over the U12 because the U3 is faster, more flexible, and is compatible with our wide array of LJTick accessories.
- 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.
- 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 overvoltage/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 datalogger 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.