Analog Inputs
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.
Analog
Outputs
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.
Digital
I/O
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.
Counter
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.
Free
Example Application Software
Includes
various example
applications, including LJlogger and LJscope. LJlogger provides
datalogger 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 labjack.com 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.
Includes
Everything for Out-of-the-Box Operation
Everything
needed (software,
screwdriver, and USB cable) is included with the LabJack U12. Installation
is very simple and takes just a few minutes:
- Connect
to the USB port on a PC running Windows 98SE/ME/2000/XP using the
included cable. The low-level drivers, which come with Windows, will
be installed automatically.
- Run the
LabJack installation program to install the high-level
drivers and example applications.
There
are 2 OEM board-only versions of the U12 available for customers
interested in designing the U12 into another product.
LabJack
U12-PH (OEM Version)
This -PH board has pin-headers installed (component side) instead of
screw-terminals, and the LED is mounted on the component side.
LabJack
U12-NTH (OEM Version)
This -NTH board does not have any through-hole components installed
(screw-terminals, pin-headers, LED, USB connector, and DB25 connector).
The OEM
versions do not include anything besides the board itself. Dimensional
drawings and software are available on the U12
downloads page.
Optional
Accessories
The
LabJack U12 comes complete, but we do offer a few optional
accessories.
-
The
CB25
provides screw-terminal connections and short-circuit/overvoltage
protection for the 16 I/O which are accessed through the DB25
connector.
-
The
RB16
provides sockets for industry standard miniature I/O modules (solid
state relays).
-
The
EI-1022
is an inexpensive and easy to use temperature probe.
-
The
EI-1040
is a single-supply dual instrumentation amp that provides high
impedance and high gain.
-
The EI-1050 Digital
Temperature/Humidity Probe.
The EI-1050 uses two digital lines on the LabJack U12 (IO0 and IO1) to retrieve
temperature and relative humidity measurements.
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