Hi Ori,
Happy Passover to everybody.
some comments on your code.
On Sat, 7 Apr 2012 10:20:35 +0300
Ori Idan wrote:
> I have a simple device that I need to send few lines of data in TCP
> protocol.
> The device should respond on each line sent.
>
> I am using the following code:
>
> #!/usr/bin/perl
> use IO::Socket::INET;
It's good that you are using the IO::Socket family of modules for socket
communications instead of the built-in and Socket.pm primitives (it is much
more recommended). However, you should add "use strict;" and "use warnings;"
to your code. See:
http://perl-begin.org/tutorials/bad-elements/ (caveat: this is a
site and a page which I have originated).
>
> my ($socket,$client_socket);
You should not pre-declare your variables. Instead do:
my $socket = INIT_EXPR() at the time you want to initialise it. I cover it on
the "bad-elements" page as well.
>
> $socket = new IO::Socket::INET (
> PeerHost => '192.168.0.20',
> PeerPort => '5086',
> Proto => 'tcp',
> ) or die "ERROR in Socket Creation : $!\n";
>
The "or die" makes me happy, but you should write:
IO::Socket::INET->new(...)
instead of:
new IO::Socket::INET
See:
http://perl-begin.org/tutorials/bad-elements/#indirect-object-notation
>
> $socket->send("a\n");
Shouldn't it be \r\n instead of \n? Note that Perl’s \n and \r are an
abstraction over the ASCII characters. For more information see:
http://onlamp.com/onlamp/2006/08/17/understanding-newlines.html
Link is currently broken (but O'Reilly says it is in maintenanace and will be
restored soon), so you can look at:
http://web.archive.org/web/20101101194037/http://onlamp.com/onlamp/2006/08/17/understanding-newlines.html
> $socket->recv($data, 128);
> print "Data 1: $data\n";
>
Where was $data declared? You should declare it using my.
> $socket->send("111000\n");
Again "\n" may be a problem.
> $socket->recv($data, 128);
>
You don't have a print here.
> It seems that the device gets the first line but not the second line.
> Does anyone have an idea what am I doing wrong?
>
Well, it might be a buffering problem:
http://perl.plover.com/FAQs/Buffering.html
Otherwise, does Wireshark tell you anything suspicious?
Regards,
Shlomi Fish
--
-
Shlomi Fish http://www.shlomifish.org/
My Public Domain Photos - http://www.flickr.com/photos/shlomif/
If you have the same ideas as everybody else, but have them one week earlier
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