Try this:

#! perl -slw
use strict;
use Time::HiRes qw[ time ];


binmode STDIN;

my $buf = '';
while( 1 ) {
    sysread( STDIN, $buf, 1 );
    my $end = time() + 7;
    sleep 0.1 while time() < $end;
    sysread( STDIN, $buf, 1024, length( $buf ) );
    printf "Got: '%f'\n", unpack 'd', $buf;
}
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The idea is that instead of trying to interrupt or timeout a read after 7 seconds; you read 1 byte; blocking until it arrives; you then wait 7 seconds and then read the rest of whatever has arrived in the interim.

When combined with this:

#! perl -sw
use strict;
use Time::HiRes qw[ time ];

binmode STDOUT;

while( 1 ) {
    my $packet = pack 'd', time;
    syswrite( STDOUT, $packet );
    sleep 30;
}
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It produces this:

C:\test>sender | listener
Got: '1423634772.508475'
Got: '1423634802.506555'
Got: '1423634832.504635'
Terminating on signal SIGINT(2)
Terminating on signal SIGINT(2)
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