Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!aioe.org!news.stack.nl!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.000 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; '(using': 0.05; 'passes': 0.05; 'python': 0.08; 'keys,': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'sockets': 0.09; 'output': 0.10; 'c++': 0.12; 'driver': 0.15; '"print"': 0.16; '>is': 0.16; 'bieber': 0.16; 'email addr:ix.netcom.com': 0.16; 'email name:wlfraed': 0.16; 'from:addr:ix.netcom.com': 0.16; 'from:addr:wlfraed': 0.16; 'from:name:dennis lee bieber': 0.16; 'message-id:@4ax.com': 0.16; 'news:': 0.16; 'output)': 0.16; 'received:wlfraed': 0.16; 'stream.': 0.16; 'url:netcom': 0.16; 'url:wlfraed': 0.16; 'wulfraed': 0.16; 'wrote:': 0.16; '(which': 0.19; 'seems': 0.19; 'trying': 0.20; 'subject:help': 0.21; 'url:home': 0.21; 'feb': 0.22; 'changed': 0.23; 'locking': 0.23; 'received:166': 0.23; 'command': 0.24; 'windows': 0.26; 'lee': 0.28; 'script': 0.28; 'print': 0.29; 'software.': 0.29; '(since': 0.30; 'clock': 0.30; 'port.': 0.30; '(the': 0.30; "didn't": 0.30; 'version': 0.31; 'developers': 0.31; 'thu,': 0.32; 'actually': 0.32; 'typically': 0.32; 'done': 0.33; 'to:addr:python-list': 0.33; 'there': 0.33; 'assignment': 0.34; 'keys': 0.34; 'header:X-Complaints-To:1': 0.34; 'running': 0.35; 'things': 0.35; 'regular': 0.35; 'however,': 0.35; 'charset:us-ascii': 0.36; 'but': 0.37; 'received:org': 0.37; 'using': 0.37; 'could': 0.37; 'signal': 0.38; 'some': 0.38; 'why': 0.39; 'tasks': 0.39; 'help': 0.39; 'subject:: ': 0.39; 'did': 0.39; 'might': 0.40; 'to:addr:python.org': 0.40; 'data': 0.40; 'order': 0.60; 'devices': 0.63; 'flight': 0.66; 'contact': 0.66; 'became': 0.66; 'gps': 0.67; 'ports': 0.67; 'dennis': 0.73; '-0800': 0.84; 'eventual': 0.84; "port's": 0.84; 'priority,': 0.84 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Dennis Lee Bieber Subject: Re: newbie socket help Date: Thu, 02 Feb 2012 11:34:26 -0500 References: <4e70f47b-89e4-46bb-929e-9b7db20e7bcc@l16g2000vbl.googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: mobile-166-147-103-241.mycingular.net X-Newsreader: Forte Agent 6.00/32.1186 X-No-Archive: YES X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 40 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1328200505 news.xs4all.nl 6893 [2001:888:2000:d::a6]:54190 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:19800 On Thu, 2 Feb 2012 05:53:22 -0800 (PST), loial wrote: >I am trying to write a python script to read data from a printer port >using python sockets, but it seems I am locking up the port. > >Is there a way to ensure that I do not block the port to other >applications? > >My knowledge of python sockets is minimal, so any help would be >appreciated. OS and Python version might be of interest... However, parallel ports are typically unshared devices (which is why any multitasking system has things like print spooling -- so multiple tasks and "print" to the spool, and the spool driver is the only process actually accessing the printer port). I still have nightmares over one assignment I had some 8 years ago: Reading a clock signal (square wave) on one of the parallel port's signal pins, in order to time a three-bit /balanced/ (using 6-pins of the output) data stream. Done on a W98 laptop (since W98 didn't have the protected ports of WinXP) using Visual C++ -- and on the laptop as the eventual plan had been to send "red" GPS decryption keys to satellites; contact with "red" keys makes the hardware it passes through highly classified, and the main hardware had to stay "open" for uncleared developers working on flight software. Unfortunately, even with the program running at the highest available Windows priority, the OS still did every few milliseconds, which led to glitches in the output stream. (The good news: by the time the DTD with the keys became available, the CONOPS had changed to use "black" keys, which did not "infect" the computer system -- so the regular command formatter could be used for uploading). -- Wulfraed Dennis Lee Bieber AF6VN wlfraed@ix.netcom.com HTTP://wlfraed.home.netcom.com/