pyParallel

Note

This module is in development (since years ;-)

Overview

This module encapsulates the access for the parallel port. It provides backends for Python running on Windows and Linux. Other platforms are possible too but not yet integrated.

This module is still under development. But it may be useful for developers.

Copyright (C) 2001-2003 Chris Liechti <cliechti(at)gmx.net>

Here is the project page on SourceForge and here is the SVN repository.

Features

  • same class based interface on all supported platforms
  • port numbering starts at zero, no need to know the port name in the user program
  • port string (device name) can be specified if access through numbering is inappropriate

Requirements

  • Python 2.2 or newer
  • “Java Communications” (JavaComm) extension for Java/Jython

Installation

Extract files from the archive, open a shell/console in that directory and let Distutils do the rest: python setup.py install

The files get installed in the “Lib/site-packages” directory in newer Python versions.

The windows version needs a compiled extension and the giveio.sys driver for Windows NT/2k/XP. The extension module can be compiled with Distutils with either MSVC or GCC/mingw32.

It is released under a free software license, see LICENSE.txt for more details.

Short introduction

>>> import parallel
>>> p = parallel.Parallel()     # open LPT1
>>> p.setData(0x55)

Examples

Please look in the SVN Repository. There is an example directory where you can find a simple terminal and more. http://pyserial.svn.sourceforge.net/viewvc/pyserial/trunk/pyparallel/examples/

API

class parallel.Parallel
__init__(port)

Open given parallel port.

setData(value)

Apply the given byte to the data pins of the parallel port.

setDataStrobe(level)

Set the “data strobe” line to the given state.

setAutoFeed(level)

Set “auto feed” line to given state.

setInitOut(level)

Set “initialize” line to given state.

getInSelected()

Read level of “select” line.

getInPaperOut()

Read level of “paper out” line.

getInAcknowledge()

Read level of “Acknowledge” line.

class parallel.parallelutil.BitaccessMeta

This mix-in class adds a few properties that allow easier bit access to the data lines. (D0 .. D7) e.g. p.D0 refers to the first bit of the data lines.

class parallel.parallelutil.VirtualParallelPort

This class provides a virtual parallel port implementation, useful for tests and simulations without real hardware.

Notes

Linux

  1. The lp(4) module must be unloaded, rmmod lp. lp claims exclusive access to the port and other programs won’t be able to use it.
  2. The ppdev(4) module needs to be loaded, modprobe ppdev. When udev is in use, (default with 2.6 kernels) this will create a /dev/parport0.
  3. The user needs to have write permissions to /dev/parport0. Many distributions have an lp group that owns the device; the simplest is to add the user account to this group. Simply changing permissions on the device is not the best strategy as they will be reverted to their defaults next time the driver is loaded.

Windows

The giveio driver must be installed as the module needs direct access to the hardware. This also means that USB parallel port adapters won’t be supported.

Misc

References

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