Hello Monks,

The following piece of code outputs some dummy data on LPT1 in WinNT. I copied it over from an old program that was outputting data via COM1. What I noticed is that the Parallel port communication is significantly slower (took about 5 seconds to switch values on LPT1) than Serial port comm. Can anyone see why? Is there a problem with Perl and writing to LPT ports under Win32? Thanks

use strict;
use English;
use Fcntl;

sysopen(PORT,"LPT1",O_RDWR) || die "can't open port\n";
syswrite(PORT,0x0);
print "Hit <enter> to change output value:";
my $in = <stdin>;
syswrite(PORT,0x1);
print "Hit <enter> to finish:";
my $in = <stdin>;

[download]

In reply to Writing to LPT1 in Win32 by gri6507

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.