labjack-unified

Classes with unified methods to interact with LabJacks U3, U6 and T7.

labjack-unified is implemented upon LabJackPython and labjack-ljm-python and provides classes to interact with any of the LabJack devices listed above, through a set of methods that are device-independent. labjack-unified was developed for the MS Windows platform.

Classes & Methods

Three classes are available (LabJackU3, LabJackU6, and LabJackT7) which have the common methods listed below. These should cover the majority of LabJack applications. There are also device specific methods as well.

Install

py -m pip install labjack-unified

Installing labjack-unified will install its dependencies: LabJackPython and labjack-ljm. Plotly will also be installed so graphs can be displayed when running the examples.

Documentation

Comprehensive documentation for labjack-unified is available here.

Examples

Nine examples are available in the documentation, with four of them requiring only a pair of wires to be executed successfully. Below is the code for lj_io_analog.py:

""" lj_io_analog.py 

Uses analog input and output channels.

This example shows how to use analog inputs and outputs in a data acquisition
loop. Accurate time execution of output events can be achieved by the use of a
timer logic in the loop. The voltage measurements are executed as fast as
possible. The main latency source is the LabJack I/O times.

Setup:
    Connect DAC0 to AIN0
    Connect DAC1 to AIN1

The LabJack unified methods in this example are:
    set_analog ....... Writes analog value to specified port(s)
    get_analog ....... Reads analog value from specified port(s)
    close ............ Closes the LabJack device 

"""
import time
import numpy as np
from labjack_unified.utils import plot_line
from labjack_unified.devices import LabJackU3, LabJackU6, LabJackT7

# To use a LabJack U6 or a T7, change the device name
# from LabJackU3 below to either LabJackU6 or LabJackT7
lj = LabJackU3()

# Assigning parameters
tstep = 0.5 # Interval between step changes (s)
t = [] # Output time array
v1 = [] # Output sampled voltage 1 array
v2 = [] # Output sampled voltage 2 array

# Initializing timers and starting main clock
tprev = 0
tcurr = 0
tstart = time.perf_counter()
# Executing acquisition loop
print('Running code for 5 seconds ...')
while tcurr <= 5:
    # Updating analog output every `tstep` seconds
    # with random voltages between 0 and 5 V
    if (np.floor(tcurr/tstep) - np.floor(tprev/tstep)) == 1:
        lj.set_analog('DAC0', 5*np.random.rand())
        lj.set_analog('DAC1', 5*np.random.rand())
    # Updating previous time and getting current time (s)
    tprev = tcurr
    tcurr = time.perf_counter() - tstart
    # Acquiring analog data as fast as possible
    # and appending values to output arrays
    t.append(tcurr)
    v1.append(lj.get_analog('AIN0'))
    v2.append(lj.get_analog('AIN1'))
print('Done.')
# Closing the device
lj.close()
del lj

# Plotting results 
plot_line([t]*2, [v1, v2], yname=['AIN0', 'AIN1'], axes='multi', marker=True)
plot_line([t[1::]], [np.diff(t)], yname=['Sampling Period (s)'])