If your file consists of 18 character records, then the easiest way to read it is to set the input record separator ($/) to a reference to the number of bytes per record: $/ = \18;. This causes readline() (<FH>) to read the file as a series of fixed length records. You can then unpack the fields within each record very easily:

#! perl -slw
use strict;
 
=comment
Offset Field Name    size 
0x0    magic_numbe   8 
0x8    retry_count   1 
0x9    number_record 1 
0x10   dc_timestamp  8
=cut

open( FH, '<', DCdata.bin" ) 
    or die "Can't open DCdata.bin file for reading!";
binmode(FH); 

$/ = \18; ## set record size

while( <FH> ) {
    my( $magic, $retry, $recnum, $timestamp ) = unpack 'A8 C C A8', $_
+;
    ## Do something with the information??
}
close FH;
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