can sink or source up to 25 mA each (total sink or source current of 200 mA max for all 16). All
digital I/O are CMOS output and TTL input except for D13-D15, which are Schmitt trigger input.
DB25 Pinouts:
1: D0
6: D5
11: +5V
16: GND
21: D11
2: D1
7: D6
12: +5V
17: GND
22: D12
3: D2
8: D7
13: +5V
18: D8
23: D13
4: D3
9: NC
14: GND
19: D9
24: D14
5: D4
10: +5V
15: GND
20: D10
25: D15
•
CNT:
The input connection to the 32-bit counter is made at screw-terminal CNT. The counter is
incremented when it detects a falling edge followed by a rising edge, and is capable of counting
frequencies up to at least 1 MHz.
•
CAL & STB:
These terminals are used during testing and calibration. The CAL terminal is a 2.5
volt reference.
•
+5V:
The LabJack has a n5 volt internal power supply. Power can be drawn from this
power supply by connecting to the +5V screw-terminals, or the +5V pins on the DB25 connector.
The total amount of current that can be drawn from the +5V pins, analog outputs, and digital
outputs, is 450 mA for most desktop computers and self-powered USB hubs. Some notebook
computers and bus-powered hubs will limit this available current to about 50 mA.
•
GND:
The GND connections available at the screw-terminals and DB25 connector provide a
common ground for all LabJack functions.
LabJack Operation
The LabJack U12 CD installs 9 example applications: LJconfig, LJcounter, LJfg, LJlogger,
LJscope, LJstream, LJtest, LJSHT, and LJSHTmulti. The LabVIEW source code for most of
these is installed in the examples directory.
Also installed are high-level drivers (ljackuw.dll), an ActiveX interface to the high-level drivers
(ljackuwx.ocx), and LabVIEW VIs which call all the DLL functions. The DLL and OCX are
installed in the Windows System directory. If the installation program can determine the
LabVIEW directory, it copies the LabVIEW drivers into that directory (\vi.lib\addons\) so they
show up on the function palette. Otherwise, the LabVIEW drivers are copied into the LabJack
installation directory (c:\Program Files\LabJack)\drivers\labview, and can manually be
transferred to the LabVIEW directory.
Example Applications
•
LJconfig:
Sets the local ID of a particular LabJack. This is useful if multiple LabJacks are
connected to the USB. Every LabJack has a local ID and serial number. The local ID is a value
between 0 and 255 that can be changed by the user. The serial number is a value between 256
and 2,147,483,647. The serial number is unique among all LabJacks and cannot be changed by
the user.
•
LJcounter:
Reads the LabJack counter and provides the frequency or count.
•
LJfg:
Outputs basic waveforms on AO0 (analog output zero).
•
LJlogger:
Sends and receives data from all channels in command/response mode.
•
LJscope:
Simulates an oscilloscope by reading data from 2 AI channels in burst mode.
•
LJstream:
Uses stream mode to read, graph, and write to file, 4 AI channels.
•
LJtest:
Runs a sequence of tests on the LabJack itself. Users will generally leave “Test Fixture
Installed” unselected and execute the tests with nothing connected to the LabJack (except the
USB of course).
•
LJSHT:
Retrieves and records data from 1 or 2 EI-1050 digital temperature/humidity probes.
•
LJSHTmulti:
Displays data from up to 20 EI-1050 digital temperature/humidity probes.
Drivers
There are 37 functions exported by the LabJack DLL., and matching functions in the OCX and
LabVIEW VIs. All functions are command/response except for AIBurst and
