pyusbdux 1.5.2

API for the USB-DUX DAQ boxes for Linux (www.linux-usb-daq.co.uk)

USB-DUX are data acquisition boxes designed for Linux

http://www.linux-usb-daq.co.uk

Installation instructions

Install pyusbdux by typing:

pip3 install pyusbdux

Quick start guide

Here are the basic steps how to use the API:

# load the module
import pyusbdux as dux

# open comedi
dux.open()

# Start asynchronous data acquisition in the background: one channel, fs=250Hz
dux.start(1,250)

# Now we read data at our convenience in a loop or timer or thread
# The following lines need to be repeated

# Let's check if samples are available
if (dux.hasSampleAvailable() == 0):
      # nope! Do something else or nothing

# Let's get a sample (array of all USB-DUX channels)
sample = dux.getSampleFromBuffer()

# do something with the sample, for example print it
print(sample)

# rinse and repeat!
# end of loop

# shutdown
dux.stop()
dux.close()

API documentation

These are the commands which allow you to access the analogue inputs asynchronously and the analogue outputs, digital input and outputs synchronously:

# opens the comedi device with comediDeviceNumber
open(comediDeviceNumber)
open()                      # opens 1st comedi device

# Starts acquisition of n_channels at the sampling rate of fs.
start(n_channels, fs)
start(n_channels)           # at fs=250

# Checks if samples are available (=1) or zero if not.
hasSampleAvailable();

# Returns one sample from all channels.
# returns always 16 values irrespective of how many channels
# are measured. Blocking call if no samples are available.
getSampleFromBuffer()

# stops the background acquisition
stop()

# writes to a digital pin the value 0 or 1
digital_out(channel, value)

# reads from a digital pin
digital_in(channel)

# writes to an analogue output pin (raw ADC values)
analoge_out(channel, value)

# gets the max raw value of the analogue output
get_analogue_out_max_raw_value()

# closes the comedi device
close()

# returns the name of the board connected
get_board_name()

Any error in comedi throws an exception in python.

Example / demo programs

In the folder https://github.com/berndporr/pyusbdux/tree/master/examples are example scripts which show you how to sample data from the analogue and digital ports.