I'm having a very frustrating problem talking to an serial-based cash register pole display. I'm working on a browser-based cash register that talks to a Perl daemon that sits on the localhost port 8080 and awaits messages that the browser sends by opening and closing a window with a localhost:8080 address and the text to display is encoded in the url in a RESTful manner.

The messages are getting to the daemon, but they don't consistently get to the LCD display. One time the message gets there, then next it might not. Sometimes half of $arg2 will display, sometimes none, sometimes all. Frustration!

I'm using : $SIG{'PIPE'} = 'IGNORE'; to keep the daemon from mysteriously failing, but I'm thinking that the problem is in HTTP::Daemon. Should I just break down and use apache on the localhost or perhaps Net::Daemon will work better?

Rather than hack away at possibilities I thought I'd post here and see if any fellow Monks have any experience with such matters.

Any insights would be appreciated.

Here's the HTTP::Daemon I'm using: 

#!/usr/bin/perl
use HTTP::Daemon;
use HTTP::Status;
my $d = HTTP::Daemon->new(LocalPort => 8080) || die;
print "Please contact me at: <URL:", $d->url, ">\n";
$SIG{'PIPE'} = 'IGNORE';
while (my $c = $d->accept) {
     while (my $r = $c->get_request) {
         if ($r->method eq 'GET' and $r->url->path =~  /display/) {
             my @args;
             my ($foo,$command,$arg1,$arg2) = split /\//, $r->url->pat
+h;
             $arg1 =~ s/%20/ /g;
             $arg2 =~ s/%20/ /g;
             $arg1 = substr($arg1,0,20);
             print "command: $command arg1: $arg1 arg2:$arg2\n";
             open SERIAL, ">>/dev/ttyS0" || die "Can't open serial";
             select((select(SERIAL), $| = 1)[0]);
             print SERIAL  "\x04\x01\x43\x31\x58\x17$arg1\x04\x01\x50\
+x44\x17 \$$arg2";
             #print   SERIAL "$$arg2 ";
             my $code = "200";
             my $mess = "Cache-Control: no-cache";
             $c->send_basic_header( $code, $mess );
             close SERIAL;
             next;
         }elsif($r->method eq 'GET' and $r->url->path =~  /scroll/) {
                print SERIAL "\x04\x01\x44\x31\x33\x17";#DISPLAY DEMO
         }else {
             $c->send_error(RC_FORBIDDEN)
         }
     }
     $c->close;
     undef($c);
}

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In reply to Serial port losing data by dshahin

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